E. coli is susceptible to ampicillin (zone 25 mm), intermediate sensitive to tetracycline (zone 14 mm), and resistant to streptomycin (zone 8 mm). S. aureus is moderately susceptible to ampicillin (zone 18 mm) and susceptible to tetracycline (zone 22 mm).
Molecular mechanisms of antimicrobial resistance in bacteria Jobir Nadhi
Molecular mechanisms of antimicrobial resistance in bacteria by highlighting the aspects of antimicrobial resistance
through a discussion of:
Bacterial strategies involved in resisting antimicrobial actions and
The molecular basis for bacterial resistance to
antimicrobial actions
some note kept in phrase are completed visualizing the picture.
Introduction to bacterial resistance to antibiotics, types of resistance, brief explaining & examples
The lecture was presented at Al-Mahmoudiya General Hospital at Wed, 17th Nov. 2021
Represented & updated as part of the training course for fresh appointed pharmacist at 16/5/2023
Combating Drug Resistance in The Intensive Care Unit (ICU)Apollo Hospitals
Drug resistance of microbes has become a major stumbling block to treating patients successfully in the ICU. There is no doubt that microbes have the capacity to mutate or acquire drug destroying enzymes, but a multitude of errors by health care providers plays a major role in facilitating the development of resistance. The maintenance of drug use discipline in closed ICUs and having a responsive microbiology department are the first steps towards prevention of microbe resistance. Having an infection control committee that is able to collect and disseminate data is the next essential step. Education of health care providers to provide uniformity of health care according to set guidelines is the culmination of this towards the goal of minimizing the development of anti microbial resistance.
immunostimulants
Immunomodulators are natural or synthetic materials that regulate the immune system and induce innate and adaptive defense mechanisms. These substances are classified into two types, immunostimulants and immunosuppressants.
Immunostimulants can enhance body's resistance against various infections through increasing the basal levels of immune response.
One of the most pressing global health issues is the problem of resistance to antimicrobial drugs. Antimicrobial resistance contributes to the uncontrolled increase in the number of pathogenic microorganisms, which leads to higher levels of infectious diseases.
Resistance to antibiotics is one of the main important facts that most nations are working on. Actually, in USA, it is considered as a health problem to solve. Why it happens? Here is a review to answer this.
Bacterial antibiotic resistance is a topic that is causing increasing concern in the health community. Antibiotics are a necessary drug to help protect and heal us from pathogenic infections that our immune system is unable to successfully combat on its own. However, bacteria are very adept at utilizing evolutionary processes to develop antibiotic resistance in order to promote their own survival, reproduction and persistence. The development of antibiotic resistant bacteria is occurring at an alarming rate. Researchers are investigating the mechanisms that confer resistance on bacteria. With techniques for genomic sequencing now readily available, understanding of genetic mechanisms of resistance and evolution as a whole has been advancing rapidly. Researchers have found that bacteria are very adept at gene mutation and horizontal gene transfer. New insights regarding pleiotrophy and epistasis have been provided through these techniques. A possible result of this research will be the discovery of new antibiotic therapies. However, as the research is demonstrating, even if we develop new antibiotics, bacteria will develop resistance to them. Thus, important considerations to be taken from the research include finding ways to slow the development of resistance as we will most likely never be able to stop it entirely.
Molecular mechanisms of antimicrobial resistance in bacteria Jobir Nadhi
Molecular mechanisms of antimicrobial resistance in bacteria by highlighting the aspects of antimicrobial resistance
through a discussion of:
Bacterial strategies involved in resisting antimicrobial actions and
The molecular basis for bacterial resistance to
antimicrobial actions
some note kept in phrase are completed visualizing the picture.
Introduction to bacterial resistance to antibiotics, types of resistance, brief explaining & examples
The lecture was presented at Al-Mahmoudiya General Hospital at Wed, 17th Nov. 2021
Represented & updated as part of the training course for fresh appointed pharmacist at 16/5/2023
Combating Drug Resistance in The Intensive Care Unit (ICU)Apollo Hospitals
Drug resistance of microbes has become a major stumbling block to treating patients successfully in the ICU. There is no doubt that microbes have the capacity to mutate or acquire drug destroying enzymes, but a multitude of errors by health care providers plays a major role in facilitating the development of resistance. The maintenance of drug use discipline in closed ICUs and having a responsive microbiology department are the first steps towards prevention of microbe resistance. Having an infection control committee that is able to collect and disseminate data is the next essential step. Education of health care providers to provide uniformity of health care according to set guidelines is the culmination of this towards the goal of minimizing the development of anti microbial resistance.
immunostimulants
Immunomodulators are natural or synthetic materials that regulate the immune system and induce innate and adaptive defense mechanisms. These substances are classified into two types, immunostimulants and immunosuppressants.
Immunostimulants can enhance body's resistance against various infections through increasing the basal levels of immune response.
One of the most pressing global health issues is the problem of resistance to antimicrobial drugs. Antimicrobial resistance contributes to the uncontrolled increase in the number of pathogenic microorganisms, which leads to higher levels of infectious diseases.
Resistance to antibiotics is one of the main important facts that most nations are working on. Actually, in USA, it is considered as a health problem to solve. Why it happens? Here is a review to answer this.
Bacterial antibiotic resistance is a topic that is causing increasing concern in the health community. Antibiotics are a necessary drug to help protect and heal us from pathogenic infections that our immune system is unable to successfully combat on its own. However, bacteria are very adept at utilizing evolutionary processes to develop antibiotic resistance in order to promote their own survival, reproduction and persistence. The development of antibiotic resistant bacteria is occurring at an alarming rate. Researchers are investigating the mechanisms that confer resistance on bacteria. With techniques for genomic sequencing now readily available, understanding of genetic mechanisms of resistance and evolution as a whole has been advancing rapidly. Researchers have found that bacteria are very adept at gene mutation and horizontal gene transfer. New insights regarding pleiotrophy and epistasis have been provided through these techniques. A possible result of this research will be the discovery of new antibiotic therapies. However, as the research is demonstrating, even if we develop new antibiotics, bacteria will develop resistance to them. Thus, important considerations to be taken from the research include finding ways to slow the development of resistance as we will most likely never be able to stop it entirely.
Rational Use of Antibiotics. Infection was a major cause of morbidity and mortality, before the development of antibiotics.
The treatment of infections faced a great challenge during those periods.
Later in 1928, the discovery of Penicillin, a beta-lactam antibiotic, by Alexander Fleming opened up the golden era of antibiotics.
It marked a revolution in the treatment of infectious diseases and stimulated new efforts to synthesize newer antibiotics.
The period between the 1950s and 1970s is considered the golden era of discovery of novel antibiotic classes, with very few classes discovered since then.
antibiotics are necessary to treat infections and chemotherapeutic agents are also used for this purpose. Chemotherapeutic agents are also used in the treatment of cancers. These therapeutic agents have limitations, specific action and a set mode of action. We can say that they are selective. The antibiotics are natural as well as synthetic in nature and have specificity for action against the microorganisms. Chemotherapeutic agents are chemical in nature and are synthesised in labs. They are less selective in action.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
1. THEME: CHEMOTHERAPY. CHEMOTHERAPEUTIC PREPARATIONS.
ANTIBIOTICS. CLASSIFICATION. METHODS OF DETERMINATION OF
ANTIBIOTIC SENSITIVITY OF BACTERIA. THE MAIN PRINCIPLES OF
RATIONAL ANTIMICROBIAL THERAPY OF DISEASES
I. STUDENTS’ INDEPENDENT STUDY PROGRAMME
1. Concept of chemotherapeutic drugs:
a – main groups of chemotherapeutic drugs;
b – chemotherapeutic index, its value;
c – mechanisms of action of the main chemotherapeutic preparations;
2. Antibiotics and mechanisms of their action:
a – what does term "antibiotics" mean;
b – classification of antibiotics according their origin, action spectrum, mechanism of
action, chemical structure;
c – units of determination of antibiotics activity;
d – antimicrobial susceptibility testing (serial dilutions, standard disks, accelerated
methods, automated liquid diffusion method);
3. Main principles of a rational chemotherapy;
4. Side effects of antibiotics, complications of chemotherapy.
5. Resistance of microbes to antibiotics:
a – mechanisms, which cause drug resistance;
b – factor of a multiple resistance to drugs (R –, r–factors), transmission of them in
bacteria;
c – methods of warning of derivation of resistant causative agents.
Various chemical substances have a lethal action on pathogenic microorganisms. They are
widely used in medical practice for treating patients with infectious diseases and in some
cases for prophylaxis.
The basis of modem chemotherapy was founded by P. Ehrlich and D. Romanowsky, who
formulated the main scientific principles and the essence of chemotherapy. P. Ehrlich devised the
principles of synthesis of medicinal substances by chemical variations: methylene blue,
derivatives of arsenic–salvarsan ('"606"), neosalvarsan ("914"). By the further development of
chemistry new medicinal preparations could be obtained.
Extensive experimental and clinical tests of chemopreparations were carried out by E
Metchnikoff.
Chemopreparations should have a specific action, a maximal therapeutic effectiveness, and
a minimal toxicity for the body.
As a characteristic of the quality of a medicinal preparation, P. Ehrlich introduced the
chemotherapeutic index which is the ratio of the maximal tolerated dose to the minimal curative
dose:
maximal tolerated dose (DT—Dosis tolerata)
---------------------------------------------------------------- > 3
minimal curative dose (DC—Dosis curativa)
The chemotherapeutic index should not be less than 3.
Chemotherapeutic preparations include a number of compounds used in medicine
Arsenic preparations (novarsenol, myarsenol, aminarsone, osarsol, etc.) are administered
in syphilis, relapsing fever, trypanosomiasis, amoebiasis, balantidiasis, anthrax, sodoku, and
other diseases.
2. Bismuth preparations (basic bismuth nitrate, xeroform, basic bismuth salicylate,
bioquinol, bismoverol, bithiurol, pentabismol, etc.) are used against enterocolitis and syphilis
Antimony compounds (tartaric antimony potassium salt, stibenil, stibozan, surmine,
solusurmine, etc.) are used for treating patients with leishmaniasis and venereal
lymphogranulomatosis.
Mercury preparations (mercury salicylate, mercuric iodide, mercury cyanide, calomel,
unguentum hydrargyri cinereum containing metallic mercury, etc.) are prescribed for treating
patients with syphilis and are used as antiseptics in pyogenic diseases.
Acridine preparations (rivanol, tripaflavine, acriflavine, acricide, flavicide, etc.) are
recommended for pyogenic diseases and inflammatory processes of the pharynx and
nasopharynx
Antimalarial substances include more than 30 preparations, e g , chinine hydrochloride,
quinine sulphate, mepacrine (acrichine), rodochin (plasmocide), proguanyl (bigumal),
pyrimethamine (chloridine), resochine, quinocide sulphones and sulphonamides, sulphadiamine,
etc.
Alkaloid preparations (emetine, etc.) are used for treating patients with amoebiasis.
Sulphonamide preparations. The introduction into practice of compounds of the
sulphonamide group (streptocid, ethasole, norsulphazol, sulphazine, methylsulphazine,
sulphadimezin, urosulphan, phthalazole, sulgine, sulphacyi, soluble sulphacyl, disulphormin,
etc.) marked a revolution in the chemotherapy of bacterial infections.
Sulphonamide preparations are used for treating pyogenic diseases, tonsillitis, scarlet fever,
erysipelas, pneumonia, dysentery, anaerobic infections, gonorrhoea, cystitis, venereal
lymphogranulomatosis, psittacosis, ornithosis, trachoma, blennorrhoea in the newborn, etc.
There are several points of view concerning the mechanism of action of sulphonamides on
microbes.
Analogs of iso-nicotinic acid: PAS, tibone, phthivazide, isoniazid, saluzid, metazid,
larusan, etoxid, sulphonin, uglon, crisanol, etc., are used for treating tuberculosis patients. Of
these phthivazide which is a derivative of isonicotinic acid hydrazide has a good therapeutic
action.
Preparations of the nitrofurane series (furazolidone, furadantine, furaguanidine) are
used for treating intestinal infections.
The group of effective antibacterial agents includes quinoxidine, dioxidine, the derivatives
of nitrofurane– furagin, soluble furagin, solafur, etc.
Antibiotics (Fr. anti against, bios life) are chemical substances excreted by some micro-
organisms which inhibit the growth and development of other microbes (in recent years
several antibiotics have been obtained semisynthetically).
Antibiotics are obtained by special methods employed m the medical industry. For the
production of antibiotics strains of fungi, actmomycetes, and bacteria are used, which are seeded
in a nutrient substrate. After a definite growth period the antibiotic is extracted, purified and
concentrated, checked for inoculousness and potency of action.
According to the character of action, antibiotics are subdivided into bacteriostatic
(tetracyclines, chloramphenicol, and others) and bactericidal (penicillines, ristomycin, and
others). Each antibiotic is characterized by a specific antimicrobial spectrum of action (narrow
or broad spectrum).
The mechanism of action of antibiotics varies.
1) inhibition the synthesis of the bacterial cell (penicillins, cephalosporins, β-lactams)
2) inhibition protein synthesis ( tetracyclines, lincomycin, erythromycin, kanamycin,
neomycin, spectinomycin, sparsomycin, fucidine, streptomycin, chloramphenicol)
3) impairment the intactness of the cytoplasmic membrane (antifungal antibiotics
poliens)
4) suppressing the synthesis and function of nucleic acids (quinolons, rifampins,
antitumor antibiotics)
3. The activity of antibiotics is expressed in international units (IU). Thus, for example, 1 IU of
penicillin (Oxford unit) is the smallest amount of preparation inhibiting the growth of a standard
Staphylococcus aureus strain.
One unit of activity (AU) corresponds to the activity of 0.6 micrograms (µg) of. the
chemically pure crystalline sodium salt of benzylpenicillin. Consequently, in 1 mg of sodium salt
of benzylpenicillin there may be 1667 AU, and in 1 mg of potassium salt — 1600 AU. For
practical purposes both preparations are manufactured with an activity not less than 1550 AU.
The concentration of dry preparations as well as of solutions is expressed as the number of
micrograms of active substance in 1 g of preparation or in 1 mg of solution.
Antibiotics are classified according to the chemical structure, the molecular mechanism,
and the spectrum of activity exerted on the cells.
According to origin, antibiotics are subdivided into the following groups.
1) Antibiotics produced by fungi.
2) Antibiotics produced by actinomycetes.
3) Antibiotics produced by bacteria
Resistance of microbes to antibiotics. With the extensive use of antibiotics in medical
practice, many species of pathogenic micro-organisms became resistant to them.
Resistance may develop to one or simultaneously to more antibiotics (multiple resistance).
The molecular mechanism of the production of resistance to antibiotics is determined by
genes localized in the bacterial nucleoids or in the plasmids, the cytoplasmic transmissible
genetic structures.
Resistance to antibiotics occurs as the result of mutations or genetic recombination
(transfer r-genes and R-plasmid due conjugation, transduction and transformation).
Mechanisms of resistance are:
1) Change of permeability of the cytoplasmic membrane and cell wall for
antibiotics
2) Synthesis proteins which transport chemicals out of the cell
3) Forming of enzymes inactivating antibiotics
4) Appearance new metabolite ways for obtaining important for life compounds
Side effects of antibiotics.
1) Toxic actions (a neurotoxic action, affect the liver, a toxic effect on the
haematopoietic organs, etc)
2) Allergic reactions (a rash, contact dermatitis, angioneurotic oedema, anaphylactic
reactions or allergic asthma, anaphylactic shock)
3) Antimicrobial agents cause the formation of numerous variants of microbes with
weak pathogenicity (atypical strains, filterable forms, L-forms) which lead to the
formation of latent forms of infections
4) Antibacterial agents may induce disorders of the genetic apparatus of the macro-
organism's cells and cause chromosomal aberrations; some of them possess a
teratogenic effect leading to the development of foetal monstrosities if they are
taken in the first days of pregnancy.
5) Development of dysbiosis
ІI. Students’ Practical activities:
1. Examine the sensitivity of S.aureus and tE.coli to decamethoxine by serial dilutions
method in a liquid media.
Method of serial dilutions in a liquid medium (description of method).
• Meal peptone broth is poured by 2-ml portions into test tubes mounted in a tube
rack by ten in each row.
• Decamethoxine solution containing 1000 µg per ml is prepared.
4. • 2 ml of this solution is added into the first test tube. Transfer with a new sterile
measuring pipette 2 ml of the mixture from this tube into the next one, and so on
until the ninth tube is reached, from which 2 ml is poured off.
• The tenth tube do not contain preparation. It serves as a control of culture growth.
• Wash the 24-hour agar culture of the studied microorganism with isotonic sodium
chloride solution.
• Determine the density of the suspension by the turbidity standard, and dilute to a
concentration of 10000 microorganisms per ml.
• A sample of 0,2 ml of the obtained suspension is inoculated into all tubes of the
row beginning from the control one.
• The results of the experiment are read following incubation of the tube at 37 °C for
18-20 hrs.
• The minimal concentration of the preparation suppressing the growth of the given
microorganism is determined by the last test tube with a transparent broth in the
presence of an intensive growth in the control one.
Another approach to antimicrobial susceptibility testing is the determination of the
minimum inhibitory concentration (MIC) that will prevent microbial growth (fig. 3). The MIC
is the lowest concentration of antimicrobial agent that prevents the growth of a
microorganism in vitro.
MIC is not designed to determine whether the antibiotic is microbicidal. It is possible to
determine the minimal bactericidal concentration (MBC). The MBC is also known as the
minimal lethal concentration (MLC) (fig. 3). The minimal bactericidal concentration is the
lowest concentration of an antibiotic that will kill a defined proportion of viable organisms
in a bacterial suspension during a specified period of exposure..
To determine the minimal bactericidal concentration, it is necessary to plate the tube
suspensions showing no growth in tube dilution (MIC) tests onto an agar growth medium. This is
done to determine whether the bacteria are indeed killed or whether they survive exposure to the
antibiotic at the concentration being tested.
Registry the MIC and fill in table:
N test tube 1 2 3 4 5 6 7 8 9 10
Concentration
of decam-ne
(µg/ml)
500 250 125 62.5 31.3 15.6 7.8 3.9 1.95 Culture
control
E. coli
S.aureus
MIC of decamethoxine for E. coli is
MIC of decamethoxine for S.aureus is
Registry the MBC and fill in table (plate test):
N sector 1 2 3 4 5 6 7 8 9 10
Concentration
of decam-ne
(µg/ml)
500 250 125 62.5 31.3 15.6 7.8 3.9 1.95 Culture
control
E. coli
S.aureus
MBC of decamethoxine for E. coli is
MBC of decamethoxine for S.aureus is
5. 2. To determine sensitivity of microorganisms to antibiotics by standard disks method (by
Kirby-Bauer’s).
Disk method.
• On the surface of solidified and slightly dried sterile agar, pour 1 ml of suspension
of 24-hour culture of the causative agent.
• Spread uniformly over the agar surface the bacterial suspension, removing its
remainder with a Pasteur pipette.
• Disks with antibiotics (5-6 disks per plate) are placed onto the surface of the
inoculated plate at a distance of 25 mm from its centre.
• The plates are incubated at 37 °C for 16-18 hrs, after which the results of the test
are read by measuring the zones of growth retardation of microorganisms around
the disks, including the diameter of the disk itself (fig.4). The size of the zones
depends on the degree of sensitivity of the causative agent to a given antibiotic.
The diameter of retardation growth zone:
D < 10 mm for resistant bacteria ( R )
D < 15 mm for intermediate sensitive bacteria (I)
D < 20 mm for moderately susceptible strain (MS)
D > 20 mm for susceptible strain (S)
Write the results of antibiotic susceptible test by disk diffusion and made the conclusion
about sensitivity certain strain.
6. 2. To determine sensitivity of microorganisms to antibiotics by standard disks method (by
Kirby-Bauer’s).
Disk method.
• On the surface of solidified and slightly dried sterile agar, pour 1 ml of suspension
of 24-hour culture of the causative agent.
• Spread uniformly over the agar surface the bacterial suspension, removing its
remainder with a Pasteur pipette.
• Disks with antibiotics (5-6 disks per plate) are placed onto the surface of the
inoculated plate at a distance of 25 mm from its centre.
• The plates are incubated at 37 °C for 16-18 hrs, after which the results of the test
are read by measuring the zones of growth retardation of microorganisms around
the disks, including the diameter of the disk itself (fig.4). The size of the zones
depends on the degree of sensitivity of the causative agent to a given antibiotic.
The diameter of retardation growth zone:
D < 10 mm for resistant bacteria ( R )
D < 15 mm for intermediate sensitive bacteria (I)
D < 20 mm for moderately susceptible strain (MS)
D > 20 mm for susceptible strain (S)
Write the results of antibiotic susceptible test by disk diffusion and made the conclusion
about sensitivity certain strain.