Biofilm is a community of microorganisms of same or different species encased in a self -produced extracellular polymeric substance on both living and non-living surfaces. Catheters are generally critical indwelling medical devices commonly used in clinical applications to enhanced flow of flu ids out of the patient’s body as well as influx of medications into human biological systems. Like many other indwelling medical devices, catheters are prone to enhanced risk of nosocomial infections which becomes a critical challenge as a result of microbial attachment to the surfaces of the catheters.
Attachment and subsequent biofilm development on catheter surfaces cause a number of persistent infections. The biofilm development increases resistance to antibiotics. However, this sometimes led to high pathogenesis, patient morbidity and mortality. This condition usually calls for a premature catheter removal which will increase the cost of treatment and improvidence of resources. This review focuses on how catheters get infected, microbial diversity among catheter biofilms, factors mediating biofilm formation on catheters and current strategies us ed in controlling biofilm formation on indwelling catheters.
Biofilm formation has been implicated in persistent tissue infections such as chronic wound infection, chronic otitis media, chronic osteomyelitis, chronic rhinosinusitis, recurrent urinary tract infection, endocarditic and cystic fibrosis-associated lung infection.They are equally resistant to various antimicrobial treatments compared to their planktonic form
Actinobacterial Diversity of Machilipatnam Coast India with an Emphasis on No...ijtsrd
Marine microbes serve as an important source for commercial bioactive compounds. The present research is focussed on the Actinobacterial diversity of Machilipatnam coast. Actinobacteria are Gram positive bacteria that resemble Fungi in having filaments forming mycelia colonies. Owing to their morphological and cultural characteristics Actinobacteria are considered a group other than Bacteria. The different Actinobacterial Strains were studied having an ability to utilize the various carbon compounds as source of energy. 27 isolates of Actinobacteria including white, green, grey, orange and pink with different morphological types were isolated from Station I and II. Among them 19 isolates were from Pedapatnam and 27 from Polatitippa. The 27 identified species were falling under 10 genera including Actinobispora, Actinomadura, Actinomyces, Microbispora, Nocardis, Nocardiopsis, Saccharomonospora, Streptomyces, Streptosporangium and Thermomonospora. Streptomyces was the most dominant genus. For the evaluation of antibacterial activity, clinical strains of bacteria such as Gram positive Staphylococcus aureus, and Streptococcus faecalis and Gram - negative Proteus vulgaris and Salmonella typhi were used. Streptomyces alboniger, S.coelicolor and S.griseus were selected to study their antagonistic activity against the above mentioned clinical bacteria. D. Srinivasa Rao | Khudsia Hussain "Actinobacterial Diversity of Machilipatnam Coast (India) with an Emphasis on Novel Preparation of Salinispora Actinobacterial Probiotics in Sustainable Aquaculture" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-6 , October 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29227.pdf Paper URL: https://www.ijtsrd.com/biological-science/biotechnology/29227/actinobacterial-diversity-of-machilipatnam-coast-india-with-an-emphasis-on-novel-preparation-of-salinispora-actinobacterial-probiotics-in-sustainable-aquaculture/d-srinivasa-rao
There are many studies about bacterial and fungal biofilm which they were considered a very big problem now days ,because of that it was one of the most virulence factors which in turns increased resistant for antibiotics
Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs
A biofilm can consist of a single microbial species or a combination of different species of bacteria, protozoa, archaea, algae, filamentous fungi, and yeast that strongly attach to each other and to biotic or abiotic surfaces
bacterial biofilm formation relies on the interaction between the bacterial cells, the substrates and the surrounding media . And the formation of bacterial biofilms is a multi-step process starting with reversible attachment to surfaces aided by intermolecular forces and hydrophobicity, and then progress to extracellular polymeric substances (EPS) production which enable the cells to permanently adhere to a surface.
there are five main phases involved in the biofilm formation process:
reversible attachment
irreversible attachment
EPS production
maturation of biofilm
dispersal/detachment
URBAS ASHIQ presentation on bacterial biofilmsUrbas Ashiq
AASALAMU ALIKUM dea friends...
i am urbas ashiq...(MSC Microbiology)
i am hear to get help and help you ghyz regarding the knowledge of microbiology and other related fields
Biofilm formation has been implicated in persistent tissue infections such as chronic wound infection, chronic otitis media, chronic osteomyelitis, chronic rhinosinusitis, recurrent urinary tract infection, endocarditic and cystic fibrosis-associated lung infection.They are equally resistant to various antimicrobial treatments compared to their planktonic form
Actinobacterial Diversity of Machilipatnam Coast India with an Emphasis on No...ijtsrd
Marine microbes serve as an important source for commercial bioactive compounds. The present research is focussed on the Actinobacterial diversity of Machilipatnam coast. Actinobacteria are Gram positive bacteria that resemble Fungi in having filaments forming mycelia colonies. Owing to their morphological and cultural characteristics Actinobacteria are considered a group other than Bacteria. The different Actinobacterial Strains were studied having an ability to utilize the various carbon compounds as source of energy. 27 isolates of Actinobacteria including white, green, grey, orange and pink with different morphological types were isolated from Station I and II. Among them 19 isolates were from Pedapatnam and 27 from Polatitippa. The 27 identified species were falling under 10 genera including Actinobispora, Actinomadura, Actinomyces, Microbispora, Nocardis, Nocardiopsis, Saccharomonospora, Streptomyces, Streptosporangium and Thermomonospora. Streptomyces was the most dominant genus. For the evaluation of antibacterial activity, clinical strains of bacteria such as Gram positive Staphylococcus aureus, and Streptococcus faecalis and Gram - negative Proteus vulgaris and Salmonella typhi were used. Streptomyces alboniger, S.coelicolor and S.griseus were selected to study their antagonistic activity against the above mentioned clinical bacteria. D. Srinivasa Rao | Khudsia Hussain "Actinobacterial Diversity of Machilipatnam Coast (India) with an Emphasis on Novel Preparation of Salinispora Actinobacterial Probiotics in Sustainable Aquaculture" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-6 , October 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29227.pdf Paper URL: https://www.ijtsrd.com/biological-science/biotechnology/29227/actinobacterial-diversity-of-machilipatnam-coast-india-with-an-emphasis-on-novel-preparation-of-salinispora-actinobacterial-probiotics-in-sustainable-aquaculture/d-srinivasa-rao
There are many studies about bacterial and fungal biofilm which they were considered a very big problem now days ,because of that it was one of the most virulence factors which in turns increased resistant for antibiotics
Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs
A biofilm can consist of a single microbial species or a combination of different species of bacteria, protozoa, archaea, algae, filamentous fungi, and yeast that strongly attach to each other and to biotic or abiotic surfaces
bacterial biofilm formation relies on the interaction between the bacterial cells, the substrates and the surrounding media . And the formation of bacterial biofilms is a multi-step process starting with reversible attachment to surfaces aided by intermolecular forces and hydrophobicity, and then progress to extracellular polymeric substances (EPS) production which enable the cells to permanently adhere to a surface.
there are five main phases involved in the biofilm formation process:
reversible attachment
irreversible attachment
EPS production
maturation of biofilm
dispersal/detachment
URBAS ASHIQ presentation on bacterial biofilmsUrbas Ashiq
AASALAMU ALIKUM dea friends...
i am urbas ashiq...(MSC Microbiology)
i am hear to get help and help you ghyz regarding the knowledge of microbiology and other related fields
The Human Microbiome Project (HMP) was a United States National Institutes of Health (NIH) research initiative to improve understanding of the microbial flora involved in human health and disease.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
Isolation and Identification of Fungi from fast food restaurants in Langa BazarIJEAB
A total of (218) samples from Eleven different foods were processed between October 2016 and February 2017 which include (Tomato, Chicken meat, red meat, falafel, potato, bread, eggplant, cabbage, celery, cucumber and onion). Samples were collected from 4 different fast food restaurants inoculated on Potato dextrose agar and Sabouraud Dextrose Agar. Isolated fungus identified morphologically and microscopically in accordance with standard procedures. Results showed that six fungal genera were associated with the selected fast food restaurants. The isolated fungal genera were Aspergillus sp., Alternaria sp., Mucor sp., Rhizopus sp., Saccharomyces sp., Brettanomyces sp. The number of total colonies in October were 236 and in February were 119 and the number of colonies were higher when cultured on Potato dextrose agar than Sabouraud Dextrose Agar. There was variation in the pattern of occurrence of the fungus in fast foods Aspergillus sp. appears to be the most pathogenic fungi that present in the food samples.
Microbiology Medical Subject Department Development - www.biomed.fitBiomed Fit
Microorganism is the general term for all tiny microorganisms that are invisible or invisible to the naked eye. The structure is relatively simple, the individual is small (generally <0.1mm), and can be divided into prokaryotes, eukaryotes and non-cells according to their evolution level and traits
The process of human understanding of microorganisms
The hard-to-understand microbial world
Many Gram negative bacteria, especially Aeromonas hydrophila are notorious for their heightened capacity to acquire and exchange antibiotic resistance genes and consequently, are commonly targeted as indicator organism for monitoring antimicrobial resistance in aquatic milieus. This study was aimed to investigate the prevalence and drug resistance patterns of Aeromonas hydrophila isolated from farm raised catfish at Epe fish farm, Lagos State, Nigeria. Swabs were aseptically taken from the kidney, intestine, liver, gills, and skin after dissecting the fish samples. The specimens were bacteriologically analyzed. After series of biochemical test, the isolated bacteria were identified presumptively according to Bergey’s Manual of determinative bacteriology, 7th Edition. Fifty-seven (57) Aeromonas hydrophila were recovered out of seventy-one (71) bacterial isolated from the 35 fish samples collected from the fish farms studied. The study reveals multiple antibiotics resistance pattern among the isolates as Aeromonas hydrophila were 100% resistant to Streptomycin, Oxytetracycline, Chloranphenicol, Pefloxacin, Ofloxacin and 70, 65 and 55% resistant to Gentamycin, Amoxycillin and Erythromycin respectively. However, all the isolates were 100% susceptible to Ciprofloxacin and Cotrimoxazole only. The presence of multidrug-resistant Aeromonas hydrophila in fish could be a vehicle of horizontal gene transfer to previously susceptible bacteria and these could constitute a serious public health hazard to human and animal in the environment. Thus, the use of antibiotics in catfish production as growth promoter or disease prevention should be discouraged and some safer, biological alternatives strategies should suffice to mitigate bacteria drug resistance and its associated problems.
Microbial Effect of Refuse Dump on the Composition of Leafy Vegetables Grown ...IJEAB
Microbial quality of vegetables grown in the vicinity of dumpsite along river Benue basin Yola Adamawa state was investigated to determine the effect of the wastes. A total of twenty samples were studied, from each of vegetable, soil and water at different distances 50, 100 and 200m from the dumpsite. Microbial analysis showed that total bacterial, mold and yeast, and coliform bacteria counts exceeded the 1,000 CFU/100ml guideline for water used in fresh produce. The result shows that total bacterial count was found to be significantly higher in the soil ranging from 4.3 x 105 – 4.78 x 106 followed by irrigation water ranging from 1.0 x 104 – 3.66 x 106 and the least was the vegetable ranging from 1.0 x104 – 9.0 x 104. Coliform bacteria count was found to be higher in the irrigation water ranging from 2.0 x 104 – 1.2 x 105 followed by the vegetables ranging from 1.0 x 104 – 2.0 x 104 and no growth of coliform was found in the soil. Mold and yeast was found to be significantly higher in the soil ranging from1.0 x 104 – TNC and was absent in the vegetables and water respectively. The higher level of microorganism observed in the dump site vegetables compared with the control vegetables show that refuse dump contribute to the microbial load in the study site. This implies that the microbial quality of vegetables may pose a health risk to the people who consume them if not properly prepared.
— The microbiological content of Lettuce (a vegetable), commonly vended in the Benin metropolis of Edo state were evaluated. Five vending locations were chosen for the study. Whole and soft rot samples were purchased and analysed for microbiological composition. Results showed high counts in soft rot samples in lettuce. Nutrient agar plated lettuce samples had bacterial counts in the range of 2.0x 103 to 4.7x10 7. Pseudomonas species was the dominant species found in lettuce samples. Bacillus species was isolated from one location in the lettuce samples. Mac Conkey agar plated lettuce plated had bacterial counts in the range of 2.3 x 10 3 to 5.7x 10 7. Enterobacter species, E. coli, and Klebsiella species were the dominant species isolated. Though, Proteus species was isolated from lettuce samples obtained from location five only. The study observes that consuming soft rot samples could pose a risk of introducing pathogens to the consumer due to their high microbial counts and could be detrimental to the health of the consumer.
biodeterioration, textiles biodeterioration, timber biodeterioration, fuels biodeterioration, glass biodeterioration, stone biodeterioration, concrete biodeterioration, rubber biodeterioration, metal biodeterioration, control of biodeterioration, prevention of biodeterioration
The Human Microbiome Project (HMP) was a United States National Institutes of Health (NIH) research initiative to improve understanding of the microbial flora involved in human health and disease.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
Isolation and Identification of Fungi from fast food restaurants in Langa BazarIJEAB
A total of (218) samples from Eleven different foods were processed between October 2016 and February 2017 which include (Tomato, Chicken meat, red meat, falafel, potato, bread, eggplant, cabbage, celery, cucumber and onion). Samples were collected from 4 different fast food restaurants inoculated on Potato dextrose agar and Sabouraud Dextrose Agar. Isolated fungus identified morphologically and microscopically in accordance with standard procedures. Results showed that six fungal genera were associated with the selected fast food restaurants. The isolated fungal genera were Aspergillus sp., Alternaria sp., Mucor sp., Rhizopus sp., Saccharomyces sp., Brettanomyces sp. The number of total colonies in October were 236 and in February were 119 and the number of colonies were higher when cultured on Potato dextrose agar than Sabouraud Dextrose Agar. There was variation in the pattern of occurrence of the fungus in fast foods Aspergillus sp. appears to be the most pathogenic fungi that present in the food samples.
Microbiology Medical Subject Department Development - www.biomed.fitBiomed Fit
Microorganism is the general term for all tiny microorganisms that are invisible or invisible to the naked eye. The structure is relatively simple, the individual is small (generally <0.1mm), and can be divided into prokaryotes, eukaryotes and non-cells according to their evolution level and traits
The process of human understanding of microorganisms
The hard-to-understand microbial world
Many Gram negative bacteria, especially Aeromonas hydrophila are notorious for their heightened capacity to acquire and exchange antibiotic resistance genes and consequently, are commonly targeted as indicator organism for monitoring antimicrobial resistance in aquatic milieus. This study was aimed to investigate the prevalence and drug resistance patterns of Aeromonas hydrophila isolated from farm raised catfish at Epe fish farm, Lagos State, Nigeria. Swabs were aseptically taken from the kidney, intestine, liver, gills, and skin after dissecting the fish samples. The specimens were bacteriologically analyzed. After series of biochemical test, the isolated bacteria were identified presumptively according to Bergey’s Manual of determinative bacteriology, 7th Edition. Fifty-seven (57) Aeromonas hydrophila were recovered out of seventy-one (71) bacterial isolated from the 35 fish samples collected from the fish farms studied. The study reveals multiple antibiotics resistance pattern among the isolates as Aeromonas hydrophila were 100% resistant to Streptomycin, Oxytetracycline, Chloranphenicol, Pefloxacin, Ofloxacin and 70, 65 and 55% resistant to Gentamycin, Amoxycillin and Erythromycin respectively. However, all the isolates were 100% susceptible to Ciprofloxacin and Cotrimoxazole only. The presence of multidrug-resistant Aeromonas hydrophila in fish could be a vehicle of horizontal gene transfer to previously susceptible bacteria and these could constitute a serious public health hazard to human and animal in the environment. Thus, the use of antibiotics in catfish production as growth promoter or disease prevention should be discouraged and some safer, biological alternatives strategies should suffice to mitigate bacteria drug resistance and its associated problems.
Microbial Effect of Refuse Dump on the Composition of Leafy Vegetables Grown ...IJEAB
Microbial quality of vegetables grown in the vicinity of dumpsite along river Benue basin Yola Adamawa state was investigated to determine the effect of the wastes. A total of twenty samples were studied, from each of vegetable, soil and water at different distances 50, 100 and 200m from the dumpsite. Microbial analysis showed that total bacterial, mold and yeast, and coliform bacteria counts exceeded the 1,000 CFU/100ml guideline for water used in fresh produce. The result shows that total bacterial count was found to be significantly higher in the soil ranging from 4.3 x 105 – 4.78 x 106 followed by irrigation water ranging from 1.0 x 104 – 3.66 x 106 and the least was the vegetable ranging from 1.0 x104 – 9.0 x 104. Coliform bacteria count was found to be higher in the irrigation water ranging from 2.0 x 104 – 1.2 x 105 followed by the vegetables ranging from 1.0 x 104 – 2.0 x 104 and no growth of coliform was found in the soil. Mold and yeast was found to be significantly higher in the soil ranging from1.0 x 104 – TNC and was absent in the vegetables and water respectively. The higher level of microorganism observed in the dump site vegetables compared with the control vegetables show that refuse dump contribute to the microbial load in the study site. This implies that the microbial quality of vegetables may pose a health risk to the people who consume them if not properly prepared.
— The microbiological content of Lettuce (a vegetable), commonly vended in the Benin metropolis of Edo state were evaluated. Five vending locations were chosen for the study. Whole and soft rot samples were purchased and analysed for microbiological composition. Results showed high counts in soft rot samples in lettuce. Nutrient agar plated lettuce samples had bacterial counts in the range of 2.0x 103 to 4.7x10 7. Pseudomonas species was the dominant species found in lettuce samples. Bacillus species was isolated from one location in the lettuce samples. Mac Conkey agar plated lettuce plated had bacterial counts in the range of 2.3 x 10 3 to 5.7x 10 7. Enterobacter species, E. coli, and Klebsiella species were the dominant species isolated. Though, Proteus species was isolated from lettuce samples obtained from location five only. The study observes that consuming soft rot samples could pose a risk of introducing pathogens to the consumer due to their high microbial counts and could be detrimental to the health of the consumer.
biodeterioration, textiles biodeterioration, timber biodeterioration, fuels biodeterioration, glass biodeterioration, stone biodeterioration, concrete biodeterioration, rubber biodeterioration, metal biodeterioration, control of biodeterioration, prevention of biodeterioration
Presentation On the research paper"External Environmental Scanning for African Nations for Business Expansion with special focus on Power Backup Products"
Vision
We envision a world wherein the pristine beauty of nature is brought inside, where fine art and technology help to deliver the peace and balance that come from authentic experience of the depths of nature. We are committed to providing practical, affordable ceiling and wall installations that accomplish this in a pure and profound way.
Biophilia
Research over the last several decades indicates that nature promotes healing in healthcare settings, improves productivity and satisfaction in the workplace, and increases well-being and reduces stress in all environments. Scientists hypothesize that people have an inherent attraction to nature, called biophilia, which makes viewing nature, even images of nature, a genuine psycho-physiological benefit. Our photography and digital cinema-based products are a fusion of nature-inspired aesthetics and leading-edge digital image making that trigger useful changes in mind and body. Sky Factory's primary concern is to design and manufacture effective Illusions of Nature™. Our clients attest to this, regularly telling us how much people enjoy the presence of our products in their hospitals, clinics, offices, shops, schools and homes.
Microbial biofilms pathogenicity and treatment strategiesPratyush Kumar Das
Microbial biofilms are complex structures wherein the planktonic cells change their growth mode to the sessile form. This kind of growth is assisted by the formation of a matrix of extracellular polymeric substances (EPS) which encapsulates the bacterial cells within it and thus, provides an additional protection. These biofilms are highly resistant to high concentration of antibiotics and poses a great threat towards public health. These biofilms are even beyond the access of a normal human immune system and are involved in infections of teeth, lungs and many other diseases. There lies an immediate need to replace the extensive use of antibiotics with new emerging strategies. The review intends to provide an insight on the various perspectives of microbial biofilms including their formation, composition, mechanism of communication (Quorum sensing) and pathogenicity. Recent emerging strategies have also been discussed that can be considered for successful eradication or inhibition of biofilms and related infections.
Staphylococcus aureus is one of the most versatile nosocomial (i.e.
acquired in hospital) and dangerous human pathogen. In spite of the
introduction of antimicrobial agents and improvements in the
frequency and morbidity of staphylococcal diseases in the twentieth
century, staphylococci have persisted as an important hospital and
community pathogen. Thereafter, methicillin-resistant S. aureus
emerged as a major pathogen worldwide. A total of 38 positive clinical
isolates from various clinical samples received from different hospitals
of Dehradun included from March 2014 to August 2014. 38 samples
had bacterial growth, among these isolates 17(44.7%) were
Staphylococcus aureus. The present study was designed to investigate
antibiotic susceptibility pattern and the role of biofilm in isolates of various clinical
samples (Urine, Blood, Semen and Pus), by examining the ability of isolates to form biofilm
and produce signaling molecules and by developing a wound model, to relate laboratory
findings with in vivo activity by exploring the possibility of detecting biofilm markers in
dressings removed from chronic infections. The presence of biofilm was confirmed by
specialized microscopy techniques or by detecting biofilm markers. Various antibiotics had a
greater effect on viability when used at higher antibiotic concentrations (≥100 mg/L) and on
younger (6h) biofilms. The antibiotics used for antibiotic susceptibility testing were
Ofloxacin, Erythromycin, Amoxicillin, and Ciprofloxacin.
A Review on Antibacterial Phytochemical Constitutions Present in Aerva lanata...BRNSS Publication Hub
Antibacterial phytochemicals have unexplored chemical structures with high therapeutic potential, additionally; phytochemicals have several advantages, including green status, different mechanisms of action from antibiotics which could help to overcome the chemotherapeutic agent resistance problem and also ability to inhibit the growth of planktonic cell and biofilm. These phytochemicals are unmatched structural diversity, and it also has no target specific. In this study, an overview of the main classes of antibacterial phytochemicals present in Aerva lanata and their mode of action against bacterial biofilm is presented. A revision about the bacterial biofilm characteristics, biofilm formation, mechanism involved against antimicrobial agents, phytochemicals properties, and their targets to eradicate biofilm, anti-biofilm properties of various phytochemicals found in A. lanata is also done. The phytochemicals such as polyphenolics interfere with the adhesion potential, quorum sensing (QS) controlled, swarming motility and biofilm formation of Escherichia coli, and Pseudomonas aeruginosa. Catechin and tannic acid also present in A. lanata were able to promote a significant reduction in biofilm formation by P. aeruginosa, and it able to block biofilm formation by E. coli and Pseudomonas putida. Antibacterial phytochemicals isolated from the different plant part of A. lanata inhibited and reduced cell-surface adhesion, methicillin-resistant bacterial biofilm formation, inhibit bacterial motility, QS, and controls biofilms of E. coli, P. aeruginosa, and Staphylococcus aureus. Phenolic acids increased the susceptibility of dual species biofilms. Peptides react against bacterial biofilm by the process of cell membrane permeabilization, intracellular targets, inhibiting nucleic acids and protein synthesis, and cell wall adhesion of Gram-negative and Gram-positive bacteria.
Microbiology Discussion 1 While Gram staining and visualization .docxannandleola
Microbiology Discussion 1
While Gram staining and visualization under a light microscope can be powerful tools to guide a clinical microbiologist in the identification of bacteria, this process rarely, if ever, is sufficient for making a definitive diagnosis of a disease caused by bacteria. On the other hand, electron microscopy is useful for not only assisting virologists in identifying disease-causing viral agents, but may perhaps provide definitive identification of these agents. Hazelton and Gelderblom (2003)1 have made the argument that electron microscopy should be the diagnostic tool of choice in many viral outbreaks because of the rapidity and fidelity of the result.
Do you agree with the statement above or not or not and why? Explain in detail and use the evidence to support your thought.
Discuss the importance of comparing multiple images of the same virus, perhaps from different patients believed to be infected with the same agent.
1Hazelton PR, Gelderblom HR. Electron microscopy for rapid diagnosis of emerging infectious agents.Emerg Infect Dis [serial online] 2003 Mar [date cited]. Available from: URL: http://www.cdc.gov/ncidod/EID/vol9no3/02-0327.htm
Reply back to classmates: Response has to be a paragraph.
1. Yes, i do agree with Hazelton and gelderblom that the electron microscopy should be the diagnostic tool of choice. I agree with this because after reading some articles i have found that the electron microscopy is fast and realiable. When you are trying to identify a disease or viral outbreak, you are going to need something that will give you fast results that you can trust. I also think when using the electron microscopy that you should use another tool to back your findings.
2. I agree with the statement, electron microscopy has two advantages over enzyme-linked immunosorbent assay and nucleic acid amplification tests. After a simple and fast negative stain preparation, the undirected, “open view” of electron microscopy allows rapid morphologic identification and differential diagnosis of different agents contained in the specimen. Details for efficient sample collection, preparation, and particle enrichment are given. Applications of diagnostic electron microscopy in clinically or epidemiologically critical situations as well as in bioterrorist events are discussed. Electron microscopy can be applied to many body samples and can also hasten routine cell culture diagnosis. To exploit the potential of diagnostic electron microscopy fully, it should be quality controlled, applied as a frontline method, and be coordinated and run in parallel with other diagnostic techniques. This just show that Gram staining is the first step identify a bacteria, when electron microscopy will make a more result to understand where and how the bacteria was produce. I feel that electron microscopy is just a more advance way to diagnosis the reasoning on how a bacteria was caused.
3. I agree with the statement above that the electron micros ...
Microbiology of Endodontic Infection.Mechanisms of MicrobialPathogenicity and Virulence Factors
Biofilm and Community-Based Microbial Pathogenesis
Biofilm and Bacterial Interactions
Biofilm Community Lifestyle
Quorum Sensing—Bacterial Intercommunication
Methods for Microbial Identification
Diversity of the Endodontic Microbiota
Primary Intraradicular Infection
Spatial Distribution of the Microbiota
Microbial Ecology and the Root Canal Ecosystem
Secondary/Persistent Infectionsand Treatment Failure
Microorganisms cause virtually all pathoses of the pulp and periapical tissues.
Once bacterial invasion of pulp tissues has taken place, both non-specific inflammation and specific immunologic response of the host have a profound effect on the progress of the disease.
Endodontic infection develops in root canals devoid of host defenses,
pulp necrosis (as a sequel to caries, trauma, periodontal disease,or iatrogenic operative procedures)
or pulp removal for treatment.
Biofilm-induced oral diseases.
ROUTES OF ROOT CANAL INFECTION
Caries
• Trauma-induced fractures
• Cracks
• Restorative procedures
• Scaling and root planing
• Attrition
• Abrasion
• Gaps in the cementoenamel junction
at the cervical root surface
• Dentinal tubules
• Direct pulp exposure
• Periodontal disease
• Anachoresis
Mechanisms of Microbial Pathogenicity and Virulence Factors
Pathogenicity : The ability of a microorganism to cause disease.
Virulence: Degree of pathogenicity of a microorganism.
Some microorganisms routinely cause disease in a given host and are called primary pathogens.
Other microorganisms cause disease only when host defenses are impaired and are called opportunistic pathogens by changing the balance of the host–bacteria relationship.
Bacterial strategies that contribute to pathogenicity include the ability to coaggregate and form biofilms.
In the pathogenesis of primary apical periodontitis
Bacteria in caries lesions form authentic biofilms adhered to dentin.
Diffusion of bacterial products through dentinal tubules induces pulpal inflammation
After pulp exposure, the exposed pulp tissue is in direct contact with bacteria and their products
and responds with severe inflammation. Some tissue invasion by bacteria may also occur.
Bacteria in the battlefront have to survive the attack from the host defenses and at the same time acquire nutrients to keep themselves alive.
In this bacteria–pulp clash, the latter invariably is “defeated” and becomes necrotic, so bacteria move forward and “occupy the territory”—that is, they colonize the necrotic tissue.
These events advance through tissue compartments, coalesce, and move toward the apical part of the canal until virtually the entire root canal is necrotic and infected.
At this stage, involved bacteria can be regarded as the early root canal colonizers or pioneer species (play an important role in the initiation of the apical periodontitis disease process, modify the environment, making it conducive to the establishment of other bacterial groups)
Springer Series on Biofilms: Vol. 9 - The Root Canal BiofilmLuis Chavez de Paz
The Root Canal Biofilm
Editors: Chávez de Paz, Luis E., Sedgley, Christine M., Kishen, Anil (Eds.)
Compiles all the basic information needed on root canal biofilms
Discusses the basic biology of root canal biofilms
One focus is on observational and experimental evidence of root canal microbial biofilms
Sheds some light on how infections caused by root canal biofilms are clinically treated and reviews the implementation of novel anti-biofilm approaches
Formation of microbial biofilms preparing by:
Assist. Lect. Aysar Ashour Khalaf
There are many studies about bacterial and fungal biofilm which they were considered a very big problem now days ,because of that it was one of the most virulence factors which in turns increased resistant for antibiotics . Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs
Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs
A biofilm can consist of a single microbial species or a combination of different species of bacteria, protozoa, archaea, algae, filamentous fungi, and yeast that strongly attach to each other and to biotic or abiotic surfaces
bacterial biofilm formation relies on the interaction between the bacterial cells, the substrates and the surrounding media . And the formation of bacterial biofilms is a multi-step process starting with reversible attachment to surfaces aided by intermolecular forces and hydrophobicity, and then progress to extracellular polymeric substances (EPS) production which enable the cells to permanently adhere to a surface
there are five main phases involved in the biofilm formation process:
reversible attachment
irreversible attachment
EPS production
maturation of biofilm
dispersal/detachment
There are various methods to detect biofilm production like :
The microtiter plate (also called 96-well plate) assay
Tissue Culture Plate (TCP).
Tube method (TM).
Congo Red Agar method (CRA).
bioluminescent assay.
piezoelectric sensors.
fluorescent microscopic examination.
INTENDED LEARNING OUTCOMES
At the end of this class, students should be able to:
1. Define Medical Laboratory Science and explain its relevance as a discipline.
2. Define Medical Microbiology and list its sub- specialties.
3. Define micro-organism and highlight the differences between Prokaryotes and Eukaryotes.
4. Differentiate between infection and infectious disease.
5. List and explain the modes of transmission of infectious agents.
6. List and explain the different methods of diagnosis of infectious diseases
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
2. 214
JibrinNdejiko M ohammed et al.: Bacterial Biofilm: A M ajor Challenge of Catheterization
the indwelling medical devices resulted fro m adhesion and
subsequent capsule formation by the adherent organisms
[7].Catheters are plastic tubes used to enhanced flow of
med ications and waste substances into and out of the human
system. Intravascular catheters are mainly used to pass
med ical substances or medications directly to the patient’s
blood circulatory system; urinary catheters on the other hand
are used to remove waste fluids from the patient’s urinary
compart ments[8]. The major challenge of catheterizat ion in
health care services has direct relationship with development
of biofilms on the catheters[9]. Biofilms can formed on
indwelling med ical devices including prosthetic heart valve,
pacemakers, central venous catheter, urinary catheter,
contact lenses, intra-uterine devices etc. thereby causing
persistent and deadly infections[10]. In another development,
Infection of patients been treated with indwelling medical
devices dated back to the fourteenth Century[11].
Meanwhile, the relat ionship between such infections and the
Kosch’s postulate in many instances are still yet to be fully
established thus imp licating biofilm as the causes of the
indwelling device-related infections[9].
2. General Overview of Biofilm
Formation
Biofilm is a co mmun ity of microorganisms of same or
different species encased in an ext racellular poly meric
matrix and are normally found on both living and non-living
surfaces. Generally, biofilm format ion is initiated with the
adherence of individual cells to the preconditioned biotic
and abiotic surface layers[12, 13]. The presence of bulk
solution or flu id on these surfaces serve as the basis or
foundation for the biofilm formation[14, 15]. This is
followed by a reversible attachment which is normally
med iated by gravitational migration of indiv idual cells,
motility of the bacteria and the shear force of the surrounding
mobile phase[16]. The irreversib le attachment occurs as a
result of concurrent production of the EPS and the strong
interactive fo rces that exist between the microbial
appendages and the surfaces[17]. This process occurs
between 20 minutes to 4hours depending on the physiology
of the species involved and the nature of the p reconditioned
surface layer[17, 18]. Meanwhile, as the microbial cell move
closer to a surface (<1n m), the in itial attach ment is facilitated
by the attractive or repulsive electrostatic and hydrophobic
interactions, steric hindrance and van der Waals forces[10].
The hydrophobic interactions have been postulated to play
important roles in the primary adhesion[19], while the
irreversible attachments are mediated by the molecular
interactions that exist between specific adhesions and the
surfaces[10]. The entire adhesion has also been exp lained
with the aid of d ifferent mo lecular cell contact theories such
as Derjagun-Landau-Verwey-Overbeck (DLVO) theory and
the extended DLVO theory and the thermodynamic
approach[14, 15, 20]
The maturation of bio film is attained when the irreversibly
attached cells develop to form a more organised and co mplex
structure whose shape depend on source of the nutrients,
however mushroom structure is common among bacteria
biofilms[21]. This is followed by microbial dispersion which
is the final stage of b iofilm develop ment and occurs when
there is alteration in the mature biofilm structure as a result
of increased shear force, depolymerisation of the EPS, use of
antimicrobials and nutrient depletion[20, 22]. This final
dispersion of biofilm is a complex process that plays a
crucial role in in itiating and transmitting infect ious diseases.
The major steps of the biofilm format ion are illustrated in the
Figure 1 belo w as adopted from Otto, 2004.
Figure 1. Themajor steps in Biofilm formation[23]
3. Journal of M icrobiology Research 2013, 3(6): 213-223
3. Contamination of the Catheters
Over 80,000 in fections associated with catheters are been
reported per annum by the intensive treatment units (ITU) of
the United State of A merican (USA) alone and
approximately 250,000 to 500,000 clin ical cases per annum
in the entire hospitals in USA[24]. These catheter-linked
infections orig inate fro m microorganisms that attached to the
implanted device in the process of insertion, cross-infection
via body contacts and/or during surgery with contaminated
surgical tools. (See Figure 2)
It has been observed that the principal waysby which
microorganis ms reach and subsequently contaminate these
catheters is usually through themovement of the skin’s
microbial flora fro m the point of insertion to the catheter
tract and along the tip of the catheter[25], Contamination of
the catheter hub as a result of its direct contact with hands or
contaminated liquids and other medical instruments,
spreading of the contamination fro m another point of
infection via blood flo w and rarely contamination as a result
of an infusate. There have been well recognized evidences
that associate catheters with infect ion and subsequent
involvement of biofilms in such infections in various
literatures. This is due to the fact that catheter itself is a
215
potential substratum for microbial adherence and subsequent
biofilm development. Apart fro m being infected by the
haematogenous route catheters can also serves as the channel
for the passage of skin microbial flora into the patient’s
body[8]. The Intravenous catheters and urinary catheters
mostly used in many hospitals have also been found to be the
frequent cause of nosocomial acquired bloodstream
infections by the coagulase-negative staphylococci which
account for about one third of episodes of catheter-related
bloodstream infection[26, 27].
Infection of the Central venous catheter (CVC) has been
reported to cause an in-hospital mortality rate of up to 35%,
long time hospitalizat ions, and many complicat ions that are
associated with the treat ment of such infections[8].
Catheter-associated urinary tract infections (CA UTIs) are
also common type of hospital acquire infect ions that are of
significant interest due to their complexity and frequent
reoccurrence. These infect ions have been linked with
Escherichia coli and Proteus mirabilis whose virulence
factors have been reported to include adhesion, motility,
biofilm format ion, resistance to immunity and acquisition of
nutrient[28].
Figure 2. Schematic flow of catheter contamination and other events that lead to infection
4. 216
JibrinNdejiko M ohammed et al.: Bacterial Biofilm: A M ajor Challenge of Catheterization
4. Role of Biofilms in Producing
Catheter Related Infections
The role of biofilms in in itiating catheter related infect ions
cannot be overemphasized. Their roles include detachment
of the cells fro m the b iofilm to in itiate b lood stream
infections and infections of urinary tract, production of
endotoxins by the biofilm encased gram negative bacteria
[29], prevention of the damaging effect of the host immune
system, transfer of p lasmid through the process of
conjugation which leads to generation of antibiotic resistance
strains[10], encrustation or obstruction of catheters with
crystallised substances produced by the bacteria.
Develop ment of gravels and pyelonephritis has also been
associated with bacterial colonization of the catheters and
subsequent biofilm formation[30]. Rodríguez et al.[31]
investigated Bio film formation in Acinetobacterbaumannii
with respect to its associated features and clinical
implications using microtiter assay and reported biofilm
formation by Fifty-six (63%) of isolated 92 strains. Thomson
et al,[8] also reported that urinary o r b loodstream infections
associated with catheter and cerebral shunt-related
men ingitis are caused by bacterial strains that have potential
to form biofilm easily.
In another develop ment Do lan (2001) stated in his rev iew
that biofilm formation on CVCs is universal, He however
emphasized that the extension and location of such biofilm is
dependent on the length of catheterization. Short-term
catheterization (<10 days) tends to favour greater b iofilm
development on the external surface while long-term
catheterizations (30 days or more) tend to favour greater
biofilm growth on the inner lu men of the catheter[32]. It is
also important to note that the accidental breakdown of
catheterization can result in early bacteria colonization of the
catheters. Evaluation and analytical co mparison of intra lu minal and extra-lu minal source of urinary catheter-related
infections revealed that unexpected breakdown of catheters
and subsequent introduction of contaminants causes
bacteriuria within first two days. However, bacteriuria
delayed to after 3-7 days when closed and sterile
catheterization was maintained[33].
The type of the flu id passing through the catheters can also
influence biofilm fo rmation in the sense that Gram-positive
organisms such as Staphylococcus epidermidis and
Staphylococcus aureusgrow poorly in intravenous fluids,
whereas Gram-negative bacteria such as P. aeruginosa,
Pantoeaspp,
Klebsiellaspp.,
Enterobacterspp.
and
Serratiasppcansustained their growth in intravenous fluids
[32]. Upon insertion, both the inner and outer surfaces of the
urinary catheters serve as targets for microbial attachment
and subsequent biofilm development. Endogenous
microorganis ms that originate fro m the gastrointestinal tract
have been found to colonized the region of the body between
the anus and the scrotrum/ vulva and ascend the catheter via
extra-lu minal route during catheter insertion. The exogenous
microorganis ms which can originate fro m cross
contamination fro m the hands of medical personnel on the
other hand, move upward the catheter via intra-lu minal route
(access of the organisms to the inner lumen of the catheter)
[34]. Investigation of a number catheters shows that the
thickness of catheter biofilms ranges fro m small patchy
layers of attached cells to extensive biofilms that often
covers the entire length of the inner lu men of the catheter and
comprising of a very high bacterial population[7]
5. Microbial Diversity in Biofilms of the
Catheter
Over the last decade, catheters, most especially the urinary
catheters has become the second commonly used indwelling
material inserted to the body of patients. This has
subsequently resulted in increased infections of urinary
catheters (IUC) with over 40% of the nosocomial infections
occurring in catheterized patients during the first 10-14 days
of catheterizat ion[30]. Microrganisms most often isolated
fro m catheter biofilms include Candida albicans, P.
aeruginosa, K. pneumoniae, Enterococcus faecalis, S.
epidermidis[32],
Acinetobacterbaumannii[8]
and
Escherichia coli, while the strongest biofilm producers are
Proteus mirabilis, E. faecalis, Candida tropicalis,
andStaphylococcus aureus which are also responsible for the
mixed species biofilms[30]. Bonkatet al[35] studied
microbial b iofilms in suprapubic catheterisation that are
nowadays used as an alternative to urethral catheterization
using conventional culture techniques and isolated a total of
428 microorganisms of wh ich Enterobacteria, Enterococcus
and P. aeruginosa were the most frequently isolated spp.
They also compared the frequency of catheter associated
with bacteriuria in suprapubic catheterisation with those of
published findings of urethral catheters[36-38] and reported
no significance difference between the two. They were
however speculative on the reduction of catheter associated
urinary tract infection with the suprapubic catheterization
[35] .
In another development, Choeet al[39] analyzes bacteria
distribution of biofilms that grows on urinary catherters
using 4 different 16S rRNA approaches namely capillary
electrophoresis, terminal restriction frag ment length
polymorphis m (T-RFLP), denaturing gradient gel
electrophoresis (DGGE), and pyrosequencing. They isolated
329 spp of which Edwardsiella, Enterobacter, Escherichia,
and Pseudomonas were the predo minant isolates for each of
the four techniques. Other represented organisms they
isolated include Moraxella, Proteus, Serratia, Yersinia,
Burkholderia, Corynebacterium, Achro mobacter, Alcaligen
es, Citrobacter, Stenotrophomonas, and Streptococcus[39].
Meanwhile, systematic antimicrobial treat ments during
catheterization have been reported to reduce microbial
diversity on the urinary catheters. Frank et al.[40] used
mo lecular techniques involving PCR and cloning to
investigate diversity of microorganis ms on the urinary
catheters and reported that both outer and inner surfaces of 8
catheters removed fro m patients undergoing no systemic
5. Journal of M icrobiology Research 2013, 3(6): 213-223
antimicrobial treat ment were colonized by 20 different
microbial species. However a wide variation existed between
the internal and outer surfaces whereas only one catheter out
of six was colonized by a single microbial species in patients
undergoing systematic antimicrobial treat ment[40, 41].
6. Factors Mediating Biofilm Formation
on Catheters
Develop ment of bio films on catheters is determined by
several variables. The microorganis ms must be able to
adhere to the exposed surface of the catheter and become
irreversibly attached. Attachment of the microbial cells is
dependent on the physiological and chemical properties of
the surface, hydrophobicity of the microorganisms and the
substratum; catheters that are both hydrophobic and
hydrophilic in nature favours attachment of wide species of
microorganis ms. Divalent cations such as calcium and
magnesiu m increases the urinary pH and ionic strength and
has been reported to facilitate bacterial attach ment[42].
Other factors include production of platelets, t issue proteins
and sera (host preconditioning films), nu mber and type of the
microbial cells, the rate at which the liquid flows through the
surface of the catheter and the composition of the liquid
itself[15, 43, 44]. As a result, the irreversible attachment and
production of EPS pro mote the format ion of bio film as the
biofilm growth rate continue to be affected by the flow rate,
nutrient and antimicrobial co mposition of the liquid passing
through the catheter and the ambient temperature[32].
In another development, the surface coating of the central
venous catheters with heparin has been reported to exhib it
the potential to reduce in vitro and in vivo microbial
attachments. Appelgrenet al. (1996) found that in v itro
adherence of coagulase-negative Staphylococci to heparin
coated catheters was drastically reduced as compared to non
heparinized catheters (p < .05). In the in vivo study of 32
central venous catheters, he observed bacteria and fungi
colonizat ion in only four o f the thirteen heparin ized catheters
while fourteen out of nineteen were colonized in the no
heparinised catheters with the coagulase-negative
Staphylococci been the most frequently isolated bacteria in
both cases[45]. It has however been observed that low citrate
concentration and sodium heparin that is widely used as
catheter lock solution can serve as a strong stimulant for S.
aureus biofilm format ion[46].
217
urinary catheters[47]. In addition to occluding the lumen of
the catheter and subsequent urine leakage or retention which
inflicts pains and distress on the patients[48], these deposits
also causes trauma to the urethra and bladder mucosa.
Encrustation and unidentified blockage can also lead to
disease conditions such as pyelonephritis, septicaemia and
shock[47]. About half of catheterized patients most
especially, the elderly people suffer fro m encrustation and
obstruction (catheter blockage). This is co mmon o f long time
catheterization and gives rise to more co mmun ity nursing
caseload[49]. A wide number of studies have demonstrated
that the steps involved in encrustation to include bacteria
contamination of the urinary tract p redominantly by P.
mirabilis and other urease producers, mult iplication and their
attachment to the catheter, subsequent biofilm format ion and
accumulat ion of the extracellular poly mers which elevate the
urine pH and triggers the stabilization of the crystallized
magnesiu m and calciu m phosphates on catheter inner
surface[48, 50-52]
Electron microscopy of catheter encrustation reveals the
presence of large nu mbers of bacilli known to easily form
biofilm conforming to the view that encrustations originate
fro m mineralized b iofilms. Bacterio logical studies of the
encrusted catheter biofilms also show the urease producing P.
mirabilis to be the dominant isolate[7, 47]. A lthough many
studies reported biofilm mineralisation to be involve in
encrustation, other studies reported involvement of bacterial
capsule polysaccharide wh ich enhance more stabilization of
the crystals[51, 53]. Thus the general methods for preventing
encrustation involves incorporating antimicrobials to the
polymers and designing catheters whose surface property
will not allow in itial bacterial attach ment[54]. A photograph
of catheter tip with encrustation (adapted fro m Hoet al.) is
shown in Figure 2.
Figure 3. Residual encrustations at the catheter tip after it removal[55]
7. Encrustation and Obstruction of the
Catheters by Biofilms
Encrustation of catheters results from the deposition of
mineral salts such as magnesium phosphate, ammoniu m
phosphate and calciu m phosphate on both the inner and outer
layer of the catheters. These mineral salts accumulate as a
result of microbial activ ities that exert functional roles to
increase the acidity of normal urine and turn it alkaline in
8. Mechanism of Antimicrobial
Resistance in Catheter Biofilms
Generally, antimicrobial agents known to be effective
against microorganisms that grow in suspension frequently
fail to exert their effects when used on the microorganisms
that grow in biofilms. Th is has been attributed to a variety of
mechanis ms wh ich includes the accumulation o f the
6. 218
JibrinNdejiko M ohammed et al.: Bacterial Biofilm: A M ajor Challenge of Catheterization
extracellular poly meric substance that tends to allows partial
or zero penetration of the antimicrobial agents in to the
microorganis ms (see Figure 4) for instance,aminoglycosides
with positive charge can bind to negatively charged
polymeric substances in the biofilm matrix and retard their
penetration. EPS can also dilute the antimicrobial
concentration before they get to the individual cells in the
biofilm, thus reducing the potency of the antibiotics against
microorganis ms[4, 56]. M icroorganisms grow slowly when
they are in biofilm and therefore become resistance to
antimicrobial agents that requires vigorous microbial growth,
the slow growth also promote poor expression of
antimicrobial binding proteins among organisms growing in
biofilms. Other mechanis ms of resistance in biofilms include
activation of mult iple genetic materials that allow
microorganis ms to alter their cell envelop, the molecular
targets, and the susceptibility to specific antimicrob ials. This
mechanis m of resistance is otherwise refers to intrinsic
resistance[57, 58].
Figure 4. Mechanisms of biofilm antimicrobial resistance[64]
Similarly Stewart and Costerton[58] reported three
mechanis ms of antimicrobial resistance in biofilms:
i. Slow penetration in which antibiotics may not be able
to move beyond the surface layers of the biofilm
ii. Develop ment of resistance phenotypes which allo ws
the bacteria growing in bio film to differentiate in to
protected phenotypes see Figure 4 also
iii. Altered microenvironment in which the antibiotic
actions are antagonised as result of zones of nutrient
accumulat ion or waste accumu lation
An increased expression of the efflu x pu mp is another
mechanis m that decreased susceptibility of biofilms to
antibiotics. Studies of b iofilm format ion by P. aeruginosa,
uropathogenicE. coli and Candida albican revealed the
specificity of the upregulation of genes that encodes
antimicrobial transporters or the factors that regulates such
transporters[59, 60]. However, investigation of biofilm
global gene expression indicated that upregulation of
antibiotic transporters is not universal and therefore only
restricted to antibiotics that possesses efflu x transporting
substrates[59].
The continuous application of chlorohexid ine for the
management of long-term bladder catheters has resulted in
the development of chlorohexidine-resistant bacteria[61]
which were later found to be resistant to many other drugs[62,
63]. The isolated resistance strain, Proteus mirabilis has
been identified to be responsible for pyelonephritis, bladder
and kidney stones and the encrustation and obstruction of
catheters in urinary tract catheterizat ion[61].
9. Current Strategies in Controlling
Biofilm Development on Catheters
One of the best ways to prevent biofilm development on
any surface is to prevent the initial attach ment of microbial
cells by avoiding contamination of the exposed surface. The
preventive measures in catheter related blood stream
infection include prevention of extra-lu minal contamination
through adoption of aseptic measures such as the use of
sterile gloves, gown, cap, and mask during the insertion of
the catheters. The use of skin antisepsis such as 2% aqueous
chlorohexidine-containing antiseptics which has been
reported to be very effective is also another pre-infection
measure[65]. The nu mber of skin micro flora at the insertion
site is an important factor that should be considered to
prevent catheter related blood stream infect ion. It is
recommended that central venous catheters be inserted at
sub-clavian sites as the catheters inserted into jugular have
been reported to possesses higher risk of microbial
colonizat ion in comparison to those inserted into a
subclavian[25, 66]. Furthermore, to prevent endoluminal
contamination, the hub should be handled with high degree
of asepsis. This can be achieved by protecting the hub using
an iodine-impregnated foam or povidone, external p rotection
of the hub, ensuring spacing in changing the infusion set and
reduced number of lu mens in the catheter. Povidone iodine is
also the commonly applied antiseptic in USA for cleansing
arterial catheter and insertion site of the central venous
catheters (CVC)[67]. Other preventive measures include
avoiding unnecessary manipulation of catheters, use of
antiseptic connectors and involvement of well-t rained
proffessionals[66]. So me of the common ly used strategies of
preventing contamination of the urinary catheters such as
systematic or direct introduction of antimicrobial agents in to
the bladder and catheter irrigation has all been reported to be
ineffective measures of preventing microbial colon izat ion of
the urinary catheters[36]. Modification of materials used for
catheter design is another economic and effective preventive
measure that is recently used in the medical industry. In this
approach, the catheter surfaces are modified to avoid
microbial adhesion[68, 69]. The proposal is to construct a
device without any fouling properties in o rder to min imize
adsorption of protein and subsequent microbial adhesion and
at the same time preserving the favourable characteristics of
the device in terms o f its strength and inertness[70]. An in
vitro study has shown that use of heparin, sodium cit rate and
sodium EDTA, can hindered biofilm development by S.
aureus indicating that they can be applied to reduce the
biofilm-associated infections in indwelling catheters[46].
Furthermore, the used of antimicrobial agents to control
7. Journal of M icrobiology Research 2013, 3(6): 213-223
biofilm format ion on medical indwelling devices has been
investigated by many researchers. Dolan[32] rev iewed that
augmentation of dextrose-heparinized left atrial catheter
with sodium metabisulfite prevented the microbial
colonizat ion of the catheters and also reported that
minocycline and rifampin imp regnated catheters experiences
less microbial colonization as compared to chlorohexidine
and silver sulfad iazine imp regnated catheters. Similarly, the
impregnation of central venous catheter with minocyclinerifampin (M/R CVCs) has been found to be efficient in
combating catheter-related blood stream infect ions and
subsequent biofilm formation by both Gram-positive and
Gram-negative organisms[71, 72]. It was however not
effective on P. aeruginosa and Candida spp.In order to
increase the antimicrobial performance of this approach,
Raadet al.[71] developed a novel minocycline/ rifamp in
catheter that included chlorhexid ine (CHX-M/R catheter)
which they found to have prolonged activity and effective in
complete inhibit ion of all the resistance strains including the
Pseudomonas aeruginosa and Candida spp. In a related
research, Kamal et al.[73] in their study of reduced
intravascular catheter infection by antibiotic bonding found
that cationic surfactant coated catheters bonded with
cephalosporine has less microbial contamination and biofilm
development than the untreated catheters. Application of
ointment containing mu ltiple antibiotics prior to insertion of
attachable subcutaneous cuff that contains silver ions,
coating the inner lumen of the catheter with an antibiotic,
using topical antibiotics and removing the contaminated
catheters can also reduce contamination of catheters and
biofilm development that acco mpany such contaminations
[32].
Dolan[74] reviewed that novel techniques such as the use
of chelating agents, biofilm d ispersants, quorum sensing
inhibitors and bacteriophages can eradicate biofilms on
intravascular catheters. The Chelating agents such as
ethylene diaminetetraacetic acid tetrasodium EDTA or
disodium EDTA and minocycline-EDTA are capable of
destabilizing the biofilm structure[75]. To support this,
Percival et al.[76] and Kite et al.[77] reported that 40 mg/ mL
of tetrasodium EDTA was able to eliminate biofilms in an in
vitro model and on hemodialysis catheters respectively.
Other forms of preventive techniques include:
i. mixture o f t igecycline and disodium EDTA with
gentamicin and disodium EDTA which has been reported to
drastically reduced biofilms of Staphylococcus species and P.
aeruginosa growing on Hickman catheter[74].
ii. Dispersal of microbial cells fro m b iofilms by shedding
of daughter cells during active growth can be achieved by
changing the nutrient levels or quorum sensing or by the use
of flow shear force.
iii. Oxid izing biocides, such as chlorine, surfactants, or
enzy mes can also cause disruption and subsequent dispersal
in biofilms[74].
iv. Unsaturated fatty acids such as cis-2-decanoic acid
produced by P. aeruginosa can disperse several clin ically
relevant biofilms in vitro. This type of dispersion is taught to
219
be as a result of degradation of the EPS by neighbouring cells
in response to the cis-2-decanoic acid (signalling mo lecule).
However this approach requires additional treatment with
antibacterial agents to prevent reattachment of the dispersed
cells[78].
v. So me strains of bacteriophage produce polysaccharide
depolymerases that are capable of degrading the biofilm EPS.
Curtin and Dolan[79] and Fu et al[80] both studied the use of
bacteriophage to prevent biofilm p revention and reported the
prevention ofS. epidermidisand P. aeruginosabiofilm growth
on phage treated catheters.
10. Techniques of Studying Catheter
Biofilms
Generally, a wide nu mber of techniques and models have
been used to study microbial biofilms on different surfaces.
Some of the co mmon techniques include d irect microscopic
techniques such as confocal laser scanning microscopy,
atomic force microscopy and scanning electron microscopy,
micro man ipulation[1, 14, 81-83]. These models involves
theuse of flow cells, 96 well micro titer plate also refered to
as the Calgary Biofilm Dev ice, colony biofilms, biofilm ring
test, micro fermentors and modified robbins devices[84, 85].
However, so me of these models yielded positive results in in
vitroinvestigation, they do not really rep resent the ideal
conditions in the studies of bio film related infection such as
catheter biofilms.In order to establish a comprehensive
technique for studying and controlling biofilms on medical
instruments such as catheters, there is need for simu lation
and development of direct and no destructive techniques and
models that represent the actual clinical conditions[86].
In order to quantify biofilms on central venous catheters,
an internationally referenced method otherwise known as
Maki's semi-quantitative method or roll plating technique
can be employed. In this method, the tip of the catheter is
removed and moved randomly over a general purpose agar
med iu m to count the number of the microorganis ms after a
specified period of incubation[32]. This method suffers the
disadvantage of not able to discover more than 1× 103
colonies and it inability to detect biofilms gro wing on the
inner lu men of the catheter[87]. An imp roved semi
quantitative roll plat ing that uses sonication and vortex to
quantify biofilms can detect up to 1 × 104 colonies per tip
however there is need for further determination of its
recovery efficiency[86]. The use of acrid ine orange to
directly stains the catheter biofilms is a rap id method that do
not modify the clinical conditions of the catheters and simp ly
record positive and negative results instead of quantifying
the cells[32, 88].
Another culture independent technique used for studying
catheter biofilms is the molecu lar technique which involves
16s rRNA, poly merase chain reaction PCR, denaturing
gradient gel electrophoresis DGGE and Fluorescence in situ
hybridizat ion FISH[39, 89, 90]. These techniques is based on
application of PCR to amp lify the seg ment of 16s rRNA
isolated from the biofilm sample, this will produced a
8. 220
JibrinNdejiko M ohammed et al.: Bacterial Biofilm: A M ajor Challenge of Catheterization
combined PCR products from the various microorganisms
that constitute the biofilm. The PCR products are
subsequently subjected to screening and separation by
DGGE to produce an order of bands which correspond to
various microbial species in the biofilm sample[89]. This
technique is faster and overcomes the problem of
misrepresentation in the rolled plate culture technique and
has been used to study microbial d iversity of biofilm samples
[39, 89].
In another development, Hassan et al[91] co mpared
Tissue Culture Plate (TCP) method, Tube method (TM) and
Congo Red Agar method (CRA ) for their ability to detect
biofilm formation in about 110 clin ical isolates and reported
the superiority of the TCP over TM and CRA, for the details
about these methods the reader is refer to the work of Hassan
et al[91]. In a related study, clement et al.[92] used crystal
violet staining, biofilm ring test, and resazurin assay to study
biofilm fo rmation in 34 clinical E. coli strains. Co mparing
the analysis of the 3 methods, they state that “there was
significant correlation between CV and RZ assay (Spearman
r = 0.68; P < 0.0001) and between CV and BRT (Spearman r
= 0.54; P = 0.0007). RZ and BRT were not significantly
correlated (Spearman r = 0.18; P = 0.28)”.
11. Conclusions
Microbial biofilms pose a major challenge to the entire
catheterization process and account for most nosocomial
infections in catheterized patients or patients under treatment
with other indwelling medical devices. Apart from resistance
to host immune system, the developments of biofilms by the
microorganis ms drastically reduce their sensitivity to the
antimicrobial agents and make them almost impossible to
eradicate using the conventional methods. In addition to
obstruction and encrustation of the catheter by these biofilms
which inflict serious pains and distress on the patients,
detachment of microbial cells fro m the catheters results in
serious infections. Although medical indwelling devices has
different design features, important factors such as duration
of catheterizat ion, co mposition of the surrounding fluids or
nature of fluid flowing through the catheter, the flow rate, the
type of the contaminating
microorganism and
preconditioned film determines the type and extent of
biofilm develop ment on indwelling catheters. Combating the
challenge posed by biofilm develop ment on indwelling
catheters is based on conducting researches that evaluate the
existing control strategies and their effectiveness while
developing both in vivo and in vitro catheter related models
of biofilms that considers the specific conditions found in
catheters in order to come up with reliable and novel
techniques. Development of novel aseptic measures that
prevents the initial colon izat ion and microbial attachment to
the devices will also help in co mbating the challenges of
biofilms in medical care. There is also need to improve the in
situ imaging of biofilms, probes for real time analysis and
characterizat ion of biofilm specific gene regulators.
REFERENCES
[1]
Pamp, S.J., C. Sternberg, and T. Tolker‐Nielsen, Insight into
the microbial multicellular lifestyle via flow‐cell technology
and confocal microscopy. Cytometry Part A, 2008. 75(2): p.
90-103.
[2]
Nielsen, M .W., C. Sternberg, S. M olin, and B. Regenberg,
Pseudomonas aeruginosa and Saccharomyces cerevisiae
biofilm in flow cells. Journal of visualized experiments: JoVE,
2011(47).
[3]
Flemming, H.-C., Biofilms and environmental protection.
Water Science & Technology, 1993. 27(7-8): p. 1-10.
[4]
Bose, S. and A.K. Ghosh, A Challenge To M edical Science.
Journal of Clinical and Diagnostic Research, 2011. 5(1): p.
127-130.
[5]
Watnick, P. and R. Kolter, Biofilm, city of microbes. Journal
of bacteriology, 2000. 182(10): p. 2675-2679.
[6]
Pynaert, K., B.F. Smets, S. Wyffels, D. Beheydt, S.D.
Siciliano, and W. Verstraete, Characterization of an
autotrophic nitrogen-removing biofilm from a highly loaded
lab-scale rotating biological contactor. Applied and
Environmental M icrobiology, 2003. 69(6): p. 3626-3635.
[7]
M orris, N., D. Stickler, and R. M cLean, The development of
bacterial biofilms on indwelling urethral catheters. World
journal of urology, 1999. 17(6): p. 345-350.
[8]
Thomsen, T.R., L. Hall-Stoodley, C. M oser, and P. Stoodley,
The role of bacterial biofilms in infections of catheters and
shunts, in Biofilm infections. 2011, Springer. p. 91-109.
[9]
Lindsay, D. and A. Von Holy, Bacterial biofilms within the
clinical setting: what healthcare professionals should know.
Journal of Hospital Infection, 2006. 64(4): p. 313-325.
[10] Basak, S., M .N. Rajurkar, R.O. Attal, and S.K. M allick,
Biofilms: A Challenge to M edical Fraternity in Infection
Control. 2013.
[11] Tenke, P., B. Kovacs, M . Jäckel, and E. Nagy, The role of
biofilm infection in urology. World journal of urology, 2006.
24(1): p. 13-20.
[12] M aría José Grande Burgos, R.L.L., M aría del Carmen López
Aguayo, Rubén Pérez Pulido, Inhibition of planktonic and
sessile Salmonella enterica cells by combinations of enterocin
AS-48, polymyxin B and biocides Food Control 2013. 30: p.
214-222.
[13] Trachoo, N. and J.F. Frank, Effectiveness of chemical
sanitizers against Campylobacter jejuni-containing biofilms.
Journal of Food Protection®, 2002. 65(7): p. 1117-1121.
[14] Garrett, T.R., M . Bhakoo, and Z. Zhang, Bacterial adhesion
and biofilms on surfaces. Progress in Natural Science, 2008.
18(9): p. 1049-1056.
[15] Katsikogianni, M . and Y. M issirlis, Concise review of
mechanisms of bacterial adhesion to biomaterials and of
techniques used in estimating bacteria–material interactions.
Eur. Cell M ater, 2004. 8: p. 37-57.
[16] Shi, X. and X. Zhu, Biofilm formation and food safety in food
9. Journal of M icrobiology Research 2013, 3(6): 213-223
industries. Trends in Food Science & Technology, 2009.
20(9): p. 407-413.
[17] Chmielewski, R. and J. Frank, Biofilm formation and control
in food processing facilities. Comprehensive reviews in food
science and food safety, 2006. 2(1): p. 22-32.
[18] Augustin, M ., T. Ali-Vehmas, and F. Atroshi, Assessment of
enzymatic cleaning agents and disinfectants against bacterial
biofilms. Journal of pharmacy and pharmaceutical science,
2004. 7: p. 55-64.
[19] Carpentier, B. and O. Cerf, Biofilms and their consequences,
with particular reference to hygiene in the food industry.
JOURNAL OF APPLIED MICROBIOLOGY, 1993. 75(6): p.
499-511.
[20] Hori, K. and S. M atsumoto, Bacterial adhesion: from
mechanism to control. Biochemical Engineering Journal,
2010. 48(3): p. 424-434.
[21] Prakash, B., B. Veeregowda, and G. Krishnappa, Biofilms: A
survival strategy of bacteria. Current science, 2003. 85(9): p.
1299-1307.
[22] Riazi, S. and K.R. M atthews, Failure of foodborne pathogens
to develop resistance to sanitizers following repeated
exposure
to
common
sanitizers.
International
Biodeterioration & Biodegradation, 2011. 65(2): p. 374-378.
[23] Otto, M ., Virulence factors of the coagulase-negative
staphylococci. Frontiers in bioscience: a journal and virtual
library, 2004. 9: p. 841-863.
[24] M aki, D.G., D.M. Kluger, and C.J. Crnich. The risk of
bloodstream infection in adults with different intravascular
devices: a systematic review of 200 published prospective
studies. in M ayo Clinic Proceedings. 2006: Elsevier.
[25] O'Grady, N.P., M. Alexander, L.A. Burns, E.P. Dellinger, J.
Garland, S.O. Heard, . . . M .L. Pearson, Guidelines for the
prevention of intravascular catheter-related infections.
Clinical infectious diseases, 2011. 52(9): p. e162-e193.
[26] Wenzel, R.P. and M .B. Edmond, The impact of
hospital-acquired
bloodstream infections. Emerging
infectious diseases, 2001. 7(2): p. 174.
[27] Salzman, M . and L. Rubin, Intravenous catheter-related
infections. Advances in pediatric infectious diseases, 1994.
10: p. 337-368.
[28] Jacobsen, S., D. Stickler, H. M obley, and M . Shirtliff,
Complicated catheter-associated urinary tract infections due
to Escherichia coli and Proteus mirabilis. Clinical
M icrobiology Reviews, 2008. 21(1): p. 26-59.
[29] Holland, S.P., R.G. M athias, D.W. M orck, J. Chiu, and S.G.
Slade, Diffuse lamellar keratitis related to endotoxins
released from sterilizer reservoir biofilms. Ophthalmology,
2000. 107(7): p. 1227-1233.
[30] Holá, V., F. Ruzicka, and M . Horka, M icrobial diversity in
biofilm infections of the urinary tract with the use of
sonication techniques. FEM S Immunology & M edical
M icrobiology, 2010. 59(3): p. 525-528.
[31] Rodríguez‐Baño, J., S. M arti, S. Soto, F. Fernández‐Cuenca, J.
Cisneros, J. Pachón, . . . L. Actis, Biofilm formation in
Acinetobacter baumannii: associated features and clinical
implications. Clinical M icrobiology and Infection, 2008.
221
14(3): p. 276-278.
[32] Donlan, R.M ., Biofilms and device-associated infections.
Emerging infectious diseases, 2001. 7(2): p. 277.
[33] Nickel, J., S. Grant, and J. Costerton, Catheter-associated
bacterium: An experimental study. Urology, 1985. 26(4): p.
369-375.
[34] Tenke, P., B. Köves, K. Nagy, S.J. Hultgren, W. M endling, B.
Wullt, . . . R. Pickard, Update on biofilm infections in the
urinary tract. World journal of urology, 2012. 30(1): p. 51-57.
[35] Bonkat, G., A.F. Widmer, M . Rieken, A. van der M erwe, O.
Braissant, G. Müller, . . . A. Bachmann, M icrobial biofilm
formation and catheter-associated bacteriuria in patients with
suprapubic catheterisation. World journal of urology, 2012: p.
1-7.
[36] Trautner, B.W. and R.O. Darouiche, Role of biofilm in
catheter-associated urinary tract infection. American journal
of infection control, 2004. 32(3): p. 177-183.
[37] Trautner, B.W., R.A. Hull, and R.O. Darouiche, Prevention of
catheter-associated urinary tract infection. Current opinion in
infectious diseases, 2005. 18(1): p. 37.
[38] Nicolle, L.E., Urinary catheter-associated infections.
Infectious Disease Clinics of North America, 2012. 26(1): p.
13-27.
[39] Choe, H.-S., S.-W. Son, H.-A. Choi, H.-J. Kim, S.-G. Ahn,
J.-H. Bang, . . . S.-S. Lee, Analysis of the distribution of
bacteria within urinary catheter biofilms using four different
molecular techniques. American journal of infection control,
2012.
[40] Frank, D.N., S.S. Wilson, A.L.S. Amand, and N.R. Pace,
Culture-independent microbiological analysis of foley
urinary catheter biofilms. PloS one, 2009. 4(11): p. e7811.
[41] Xu, Y., C. M oser, W.A. Al-Soud, S. Sørensen, N. Høiby, P.H.
Nielsen,
and
T.R.
Thomsen,
Culture-dependent
and-independent investigations of microbial diversity on
urinary catheters. Journal of clinical microbiology, 2012.
50(12): p. 3901-3908.
[42] Brisset, L., V. Vernet-Garnier, J. Carquin, A. Burde, J.
Flament, and C. Choisy, In vivo and in vitro analysis of the
ability of urinary catheter to microbial colonization].
Pathologie-biologie, 1996. 44(5): p. 397.
[43] Baillie, G.S. and L.J. Douglas, M atrix polymers of Candida
biofilms and their possible role in biofilm resistance to
antifungal agents. Journal of Antimicrobial Chemotherapy,
2000. 46(3): p. 397-403.
[44] Chandra, J., D.M . Kuhn, P.K. Mukherjee, L.L. Hoyer, T.
M cCormick, and M .A. Ghannoum, Biofilm formation by the
fungal pathogenCandida albicans: development, architecture,
and drug resistance. Journal of bacteriology, 2001. 183(18): p.
5385-5394.
[45] Appelgren, P., U. Ransjo, L. Bindslev, F. Espersen, and O.
Larm, Surface heparinization of central venous catheters
reduces microbial colonization in vitro and in vivo: results
from a prospective, randomized trial. Critical care medicine,
1996. 24(9): p. 1482-1489.
[46] Shanks, R.M ., J.L. Sargent, R.M . M artinez, M .L. Graber, and
G.A. O'T oole, Catheter lock solutions influence
staphylococcal biofilm formation on abiotic surfaces.
10. JibrinNdejiko M ohammed et al.: Bacterial Biofilm: A M ajor Challenge of Catheterization
222
Nephrology
2247-2255.
Dialysis Transplantation, 2006. 21(8): p.
[47] Stickler, D., L. Ganderton, J. King, J. Nettleton, and C.
Winters, Proteus mirabilis biofilms and the encrustation of
urethral catheters. Urological research, 1993. 21(6): p.
407-411.
[48] Gorman, S.P. and M .M . Tunney, Assessment of encrustation
behaviour on urinary tract biomaterials. Journal of
biomaterials applications, 1997. 12(2): p. 136-166.
[49] Choong, S., S. Wood, C. Fry, and H. Whitfield, Catheter
associated urinary tract infection and encrustation.
International journal of antimicrobial agents, 2001. 17(4): p.
305-310.
[50] M orris, N.S. and D.J. Stickler, The effect of urease inhibitors
on the encrustation of urethral catheters. Urological research,
1998. 26(4): p. 275-279.
[51] Dumanski, A.J., H. Hedelin, A. Edin-Liljegren, D.
Beauchemin, and R. M cLean, Unique ability of the Proteus
mirabilis capsule to enhance mineral growth in infectious
urinary calculi. Infection and immunity, 1994. 62(7): p.
2998-3003.
[52] Winters, C., D. Stickler, T. Howe, N. Wilkinson, and C.
Buckley, Some observations on the structure of encrusting
biofilms of Proteus mirabilis on urethral catheters. Cells and
M aterials, 1995. 5(3): p. 245-253.
[53] Clapham, L., R. M cLean, J. Nickel, J. Downey, and J.
Costerton, The influence of bacteria on struvite crystal habit
and its importance in urinary stone formation. Journal of
crystal growth, 1990. 104(2): p. 475-484.
[54] Stickler, D., A. Evans, N. Morris, and G. Hughes, Strategies
for the control of catheter encrustation. International journal
of antimicrobial agents, 2002. 19(6): p. 499-506.
[55] Ho, C.C., Y. Khandasamy, P. Singam, E.H. Goh, and Z.M .
Zainuddin, Encrusted and incarcerated urinary bladder
catheter: what are the options? Libyan Journal of M edicine,
2010. 5(1).
[56] Stewart, P.S. and J. William Costerton, Antibiotic resistance
of bacteria in biofilms. The Lancet, 2001. 358(9276): p.
135-138.
[57] Cox, G. and G.D. Wright, Intrinsic antibiotic resistance:
M echanisms, origins, challenges and solutions. International
Journal of M edical M icrobiology, 2013.
[58] Stewart, P.S., M echanisms of antibiotic resistance in bacterial
biofilms. International Journal of M edical M icrobiology,
2002. 292(2): p. 107-113.
[59] Lynch, A.S. and G.T. Robertson, Bacterial and fungal biofilm
infections. Annu. Rev. M ed., 2008. 59: p. 415-428.
[60] Andes, D., J. Nett, P. Oschel, R. Albrecht, K. M archillo, and
A. Pitula, Development and characterization of an in vivo
central venous catheter Candida albicans biofilm model.
Infection and immunity, 2004. 72(10): p. 6023-6031.
[61] Stickler,
D.,
Susceptibility
of
antibiotic‐resistant
Gram‐negative bacteria to biocides: a perspective from the
study of catheter biofilms.Journal of Applied M icrobiology,
2002. 92(s1): p. 163S-170S.
[62] Adamus-Bialek, W., E. Zajac, P. Parniewski, and W. Kaca,
Comparison of antibiotic resistance patterns in collections of
Escherichia coli and Proteus mirabilis uropathogenic strains.
M olecular biology reports, 2013: p. 1-7.
[63] Tumbarello, M ., E.M . Trecarichi, B. Fiori, A.R. Losito, T.
D'Inzeo, L. Campana, . . . G. Fadda, M ultidrug-resistant
Proteus mirabilis bloodstream infections: risk factors and
outcomes. Antimicrobial agents and chemotherapy, 2012.
56(6): p. 3224-3231.
[64] Drenkard, E., Antimicrobial resistance of Pseudomonas
aeruginosa biofilms. M icrobes and infection, 2003. 5(13): p.
1213-1219.
[65] Segev, G., T. Bankirer, D. Steinberg, M . Duvdevani, N.
Shapur, M . Friedman, and E. Lavy, Evaluation of Urinary
Catheters Coated with Sustained‐Release Varnish of
Chlorhexidine in M itigating Biofilm Formation on Urinary
Catheters in Dogs. Journal of Veterinary Internal M edicine,
2013. 27(1): p. 39-46.
[66] Sitges-Serra, A. and M . Girvent, Catheter-related
bloodstream infections. World journal of surgery, 1999. 23(6):
p. 589-595.
[67] Clemence, M .A., D. Walker, and B.M . Farr, Central venous
catheter practices: results of a survey. American journal of
infection control, 1995. 23(1): p. 5-12.
[68] Knetsch, M .L. and L.H. Koole, New strategies in the
development of antimicrobial coatings: the example of
increasing usage of silver and silver nanoparticles. Polymers,
2011. 3(1): p. 340-366.
[69] Raynor, J.E., J.R. Capadona, D.M . Collard, T.A. Petrie, and
A.J. García, Polymer brushes and self-assembled monolayers:
Versatile platforms to control cell adhesion to biomaterials
(Review). Biointerphases, 2009. 4(2): p. FA3-FA16.
[70] Bazaka, K., M .V. Jacob, R.J. Crawford, and E.P. Ivanova,
Plasma-assisted surface modification of organic biopolymers
to prevent bacterial attachment. Acta biomaterialia, 2011.
7(5): p. 2015-2028.
[71] Raad, I., J.A. Mohamed, R.A. Reitzel, Y. Jiang, S. Raad, M .
Al Shuaibi, . . . R.Y. Hachem, Improved antibioticimpregnated catheters with extended-spectrum activity
against resistant bacteria and fungi. Antimicrobial agents and
chemotherapy, 2012. 56(2): p. 935-941.
[72] Esposito, S., S. Purrello, E. Bonnet, A. Novelli, F. Tripodi, R.
Pascale, . . . G. M ilkovich, Central venous catheter-related
biofilm
infections:
An
up-to-date
focus
on
meticillin-resistantStaphylococcus aureusJournal of Global
Antimicrobial Resistance, 2013.
[73] Kamal, G.D., M .A. Pfaller, L.E. Rempe, and P.J. Jebson,
Reduced intravascular catheter infection by antibiotic
bonding. JAM A: the journal of the American M edical
Association, 1991. 265(18): p. 2364-2368.
[74] Donlan, R.M ., Biofilm elimination on intravascular catheters:
important considerations for the infectious disease
practitioner. Clinical infectious diseases, 2011. 52(8): p.
1038-1045.
[75] Raad, I., J. Rosenblatt, R. Reitzel, Y. Jiang, T. Dvorak, and R.
Hachem, Chelator-Based Catheter Lock Solutions in
Eradicating Organisms in Biofilm. Antimicrobial agents and
11. Journal of M icrobiology Research 2013, 3(6): 213-223
chemotherapy, 2013. 57(1): p. 586-588.
[76] Percival, S.L., P. Kite, K. Eastwood, R. M urga, J. Carr, M .J.
Arduino, and R.M . Donlan, Tetrasodium EDTA as a novel
central venous catheter lock solution against biofilm.
Infection control and hospital epidemiology, 2005. 26(6): p.
515-519.
[77] Kite, P., K. Eastwood, S. Sugden, and S. Percival, Use of in
vivo-generated biofilms from hemodialysis catheters to test
the efficacy of a novel antimicrobial catheter lock for biofilm
eradication in vitro. Journal of clinical microbiology, 2004.
42(7): p. 3073-3076.
[78] Davies, D.G. and C.N. M arques, A fatty acid messenger is
responsible for inducing dispersion in microbial biofilms.
Journal of bacteriology, 2009. 191(5): p. 1393-1403.
[79] Curtin, J.J. and R.M . Donlan, Using bacteriophages to reduce
formation of catheter-associated biofilms by Staphylococcus
epidermidis. Antimicrobial agents and chemotherapy, 2006.
50(4): p. 1268-1275.
[80] Fu, W., T. Forster, O. M ayer, J.J. Curtin, S.M . Lehman, and
R.M . Donlan, Bacteriophage cocktail for the prevention of
biofilm formation by Pseudomonas aeruginosa on catheters in
an in vitro model system. Antimicrobial agents and
chemotherapy, 2010. 54(1): p. 397-404.
223
in vitro to in vivo M odels of Bacterial Biofilm-Related
Infections. Pathogens, 2013. 2(2): p. 288-356.
[85] Chavant, P., B. Gaillard-M artinie, R. Talon, M . Hébraud, and
T. Bernardi, A new device for rapid evaluation of biofilm
formation potential by bacteria. Journal of microbiological
methods, 2007. 68(3): p. 605-612.
[86] Kadurugamuwa, J.L., L. Sin, E. Albert, J. Yu, K. Francis, M .
DeBoer, . . . P.R. Contag, Direct continuous method for
monitoring biofilm infection in a mouse model. Infection and
immunity, 2003. 71(2): p. 882-890.
[87] Contag, P.R., I.N. Olomu, D.K. Stevenson, and C.H. Contag,
Bioluminescent indicators in living mammals. Nature
medicine, 1998. 4(2): p. 245-247.
[88] Siragusa, G., Real Time M onitoring of E. Coli O157: H7
Adherence to Beef Carcass Surface Tissue using a
Bioluminescence Reporter. Applied and Environmental
M icrobiology.
[89] Guembe, M ., M . M arín, P. M artín-Rabadán, A. Echenagusia,
F. Camúñez, G. Rodríguez-Rosales, . . . E. Bouza, Use of
Universal 16S rRNA Gene PCR as a Diagnostic Tool for
Venous Access Port-Related Bloodstream Infections. Journal
of clinical microbiology, 2013. 51(3): p. 799-804.
[81] Teodósio, J., M . Simões, L. M elo, and F. M ergulhão, Flow
cell hydrodynamics and their effects on E. coli biofilm
formation under different nutrient conditions and turbulent
flow. Biofouling, 2011. 27(1): p. 1-11.
[90] Choe, H.-S., H.-J. Kim, S.-J. Lee, J.-Y. Lee, S.-S. Lee, and
Y.-H. Cho, Evaluation of the bacterial distribution within the
biofilm by denaturing gradient gel electrophoresis in the rat
model of urinary catheters. International urology and
nephrology, 2013: p. 1-6.
[82] Crusz, S.A., R. Popat, M.T. Rybtke, M . Cámara, M . Givskov,
T. Tolker-Nielsen, . . . P. Williams, Bursting the bubble on
bacterial biofilms: a flow cell methodology. Biofouling, 2012.
28(8): p. 835-842.
[91] Hassan, A., J. Usman, F. Kaleem, M . Omair, A. Khalid, and
M . Iqbal, Evaluation of different detection methods of biofilm
formation in the clinical isolates. The Brazilian Journal of
Infectious Diseases, 2011. 15(4): p. 305-311.
[83] Katsikogianni, M . and Y. M issirlis, Interactions of bacteria
with specific biomaterial surface chemistries under flow
conditions. Acta biomaterialia, 2010. 6(3): p. 1107-1118.
[92] Crémet, L., S. Corvec, E. Batard, M . Auger, I. Lopez, F.
Pagniez, . . . N. Caroff, Comparison of three methods to study
biofilm formation by clinical strains ofEscherichia coli.
Diagnostic microbiology and infectious disease, 2013. 75(3):
p. 252-255.
[84] Lebeaux, D., A. Chauhan, O. Rendueles, and C. Beloin, From