BIOFILMS
I.Sophia
Roll no: P-1699
VBM
Biofilms
• Layman terms – Bacteria can join together on any surface & start to form a protective
covering around their gro...
Biofilm formation
Biofilms
IMPORTANT FACTORS IN BIOFILM FORMATION
 Cell attachment
 Extracellular polysaccharides (EPS)
 Cell-cell commun...
Basic units of biofilm: microcolonies of homogenous
and heterogenous bacterial species. Microbial cells – 15 % ; Matrix m...
Quorum sensing
Biofilm requires self organisation and co-operation among the cells.
Cell to cell signaling – Role in bio...
Significance of biofilms
Role of biofilms in antibiotic resistance
Delayed penetration of the antimicrobial agent
EPS – diffusional barrier ; del...
Role of biofilms in disease production
 Detachment of cells and cell aggregates : Bacteria detached from biofilm - role i...
Role of biofilms in bovine respiratory disease
complex
Biofilms aid in resistance to antimicrobial drugs & evasion of host...
Role of biofilms in disease production
Leptospira sps – biofilm formers - new insights in pathogenesis
 Leptospira interr...
Biofilms in medical devices
 biofilms – frequent menace in urinary
catheters, contact lenses , prosthetic
heart valves , ...
Biofilm examination & measurement
Differential interference contrast microscopy
Transmission electron microscopy
Scanni...
Coating indwelling devices with bactericidals, biocides, anti-adhesion compounds
Summary
 Bacteria adopt biofilm as a success strategy to colonize and produce
disease.
Biofilm is the predominant mode o...
Biofilms
Biofilms
Biofilms
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Biofilms

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Basic information about biofilms in microbiology

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Biofilms

  1. 1. BIOFILMS I.Sophia Roll no: P-1699 VBM
  2. 2. Biofilms • Layman terms – Bacteria can join together on any surface & start to form a protective covering around their group. • Microbially derived sessile community consists of cells irreversibly attached to a substratum • Embedded in a matrix of extracellular polymeric substances produced by them • Exhibit altered phenotype w.r.t growth rate & gene transcription • Significance: Protect and allow bacteria to survive and thrive in hostile environments • Withstand host immune responses, much less susceptible to antibiotics and disinfectants • Animalcules are observed by Anton Von Leeuwenhok from the biofilms of his dental plaque • Research in biofilms begin after 1980s.
  3. 3. Biofilm formation
  4. 4. Biofilms IMPORTANT FACTORS IN BIOFILM FORMATION  Cell attachment  Extracellular polysaccharides (EPS)  Cell-cell communication (Quorum sensing) Cell attachment • Cell surface hydrophobicity : bacterial attachment to each other & to surfaces – interaction of hydrophobic domains Extracellular filamentous appendages in biofilm formation • Flagella : transport , initial cell-surface interactions • Pilli / fimbriae : adherence to bacterial cells and inorganic particles • Prostheca / Stalks : attachment factors in microbes • At the end is an adhesive disk ‘Holdfast’ – attachment to surfaces
  5. 5. Basic units of biofilm: microcolonies of homogenous and heterogenous bacterial species. Microbial cells – 15 % ; Matrix material -85 % EPS : polysaccharides, proteins ( 75-90%) nucleic acids, lipds, phospholipids & humic substances Role of EPS in biofilms Acts as a barrier – only diffusion transport is possible Delays / prevents antimicrobials passage due to barrier effect or chemical interactions Cell-cell communication & community behaviour  Polysaccharides & proteins – fundamental structural elements of biofilms, mechanical strength Lipids , nucleic acids – stability of biofilms Extracellular DNA – required for initial biofilm establishment by P.aeruginosa Composition of biofilms
  6. 6. Quorum sensing Biofilm requires self organisation and co-operation among the cells. Cell to cell signaling – Role in biofilm formation ,achieved by quorum sensing.  Cell density-dependent signaling system mediated by chemicals called autoinducer molecules produced by bacteria during growth. When the bacterial population reaches the quorum level ie.the signal concentration reaches a threshold concentration sufficient to facilitate binding to the receptor. Binding of the autoinducers is followed by activation or repression of target genes. Quorum sensing allows bacteria to display a unified response that benefits the population  AIs : oligopeptides – G+ bacteria ; N-Acetyl homoserine – G- bacteria Boronated diester moleculles – inter species communication – both G+ , G- bacteria Symbiosis, transfer of conjugative plasmids, sporulation, antimicrobial peptide synthesis, regulation of virulence – mediated by quorum sensing.
  7. 7. Significance of biofilms
  8. 8. Role of biofilms in antibiotic resistance Delayed penetration of the antimicrobial agent EPS – diffusional barrier ; delays rate of transport of drugs  Chemical action of drugs with EPS  Bacteria intact in biofilms more resistant than single cells  Altered growth rate of organisms in biofilms  organisms grow more slowly in biofilms  Slow uptake of antimicrobials  Actively growing and dividing cells are required for drug action
  9. 9. Role of biofilms in disease production  Detachment of cells and cell aggregates : Bacteria detached from biofilm - role in disease production in blood and urinary tract G- bacteria in biofilms – produce endotoxins Extracellular slime produced by S.epidemidis - interferes macrophage mediated phagocytosis Opsonizing antibodies – ineffective against bacteria in biofilms in CCF. Antibodies produced by vaccination – ineffective when pathogen is encysted in biofilms.  Biofilm resident bacteria – resistant to oxidative killing (E.coli) Humans : biofilms play role in cystic fibrosis, otitis media, endocarditis, periodontitis etc.
  10. 10. Role of biofilms in bovine respiratory disease complex Biofilms aid in resistance to antimicrobial drugs & evasion of host immune response
  11. 11. Role of biofilms in disease production Leptospira sps – biofilm formers - new insights in pathogenesis  Leptospira interrogans – biofilm formation aid in long term survival in aqueous environment Biofilm formation and disease production - play an important role in keeping the bacteria alive in the kidneys of animals such as rats without causing disease.
  12. 12. Biofilms in medical devices  biofilms – frequent menace in urinary catheters, contact lenses , prosthetic heart valves , central venous catheters  biofilms grow well in lens care fluids. ReNu lens care fluid used worldwide – supports biofilms formed by the fungus Fusarium sps. Also formed in food substances, vegetables
  13. 13. Biofilm examination & measurement Differential interference contrast microscopy Transmission electron microscopy Scanning electron microscopy Atomic force microscopy Confocal laser scanning microscopy - FISH & 16S – 23S rRNA hybridization  Roller tube method Endoluminal brush biofilm measurement  Alginate brush method BIOFILM INTERVENTION STRATEGIES Prevent initial device contamination Minimize initial microbial cell attachment to the device Penetration of EPS matrix and cell killing Removal of the device
  14. 14. Coating indwelling devices with bactericidals, biocides, anti-adhesion compounds
  15. 15. Summary  Bacteria adopt biofilm as a success strategy to colonize and produce disease. Biofilm is the predominant mode of bacterial growth Development of non invasive early biofilm detection methods will aid in great success in bioilm treatment Novel treatments should aim at distruption of quorum sensing and inhibit the transcription of genes involved in biofilm formation.

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