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MICROBIAL BIOFILMS
(SEM OF BACTERIAL BIOFILMS)

What is microbial biofilm?

A biofilm is any group of microorganisms in which cells stick to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS). Biofilm extracellular polymeric substance, which is also referred to as slime (although not everything described as slime is a biofilm), is a polymeric conglomeration generally composed of extracellular DNA, proteins, and polysaccharides. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium.
Text: Wikipedia

Pseudomonas aeruginosa biofilms

Treatment of chronic wounds
with Hyiodine
(clinical data)

Micrograph of Pseudomonas aeruginosa biofilm.

SEM image showing attachment and biofilm formation by Pseudomonas aeruginosa cells on the surface of polycarbonate plastic.

Biofilm formed by P.aeruginosa on the surface of polycarbonate plastic.

Pseudomonas aeruginosa
biofilm.

Pseudomonas aeruginosa
biofilm. 48 hours, TSB medium.

Pseudomonas aeruginosa
biofilm. 48 hours, TSB medium.

Staphylococcus aureus biofilms

Scanning electron micrographs of S.aureus showing biofilm of coccoid cells blanked by extracellular polymer matrix.

Staphylococcus aureus
biofilm.

Scanning electron microscopy (SEM) image showing attachment and initiation of biofilm formation by S.aureus.

Staphylococcus aureus
forming biofilm. The biofilm is relatively immature (48 hours, TSB medium).

SEM image showing attachment and initiation of biofilm formation by Staphylococcus aureus.

S.aureus SEM

ThisSEMmicrograph shows a bloom of S.aureus. The bloom is loosely associated by an extracellular matrix. The biofilm is relatively immature.

Staphylococcus aureus SEM

Several pathogenic bacterial species found in the environment are capable of forming complex multi-cellular structure, known as biofilm, on the surfaces. Bacteria embedded in biofilms are often difficult to eradicate with standard antibiotic regimens and inherently resistant to host immune responses. Staphylococcus aureus is one of the well known pathogens that has an inherent ability to form biofilms on biotic and abiotic surfaces.

Staphylococcus epidermidis biofilms

Staphylococcus epidermidis and S. aureus are the most frequent causes of nosocomial infections and infections on indwelling medical devices, which characteristically involve biofilms. The Nosocomial Infections Surveillance System (http://www.cdc.gov/ncidod/hip/NNIS/2004NNISreport.pdf) recognizes S. aureus and CoNS (coagulase-negative staphylococci, i.e. S. epidermidis and most other staphylococci other than S. aureus) as the most frequently isolated nosocomial pathogens from intensive care unit patients. An extremely high percentage of these isolates are resistant to methicillin (89% CoNS compared to 59.5% for S. epidermidis). In addition to specific antibiotic resistance, which is based on the acquisition of genetic resistance factors and may be chromosomally, or more often plasmid-encoded, staphylococci have non-specific mechanisms of resistance, of which biofilm formation is undoubtedly the most important [1].

Scanning electron microscopy (SEM) image showing attachment and initiation of biofilm formation by S.epidermidis.

SEM visualisation of biofilm formed by Staphylococcus epidermidis.

Biofilm formed by S.epidermidis.

Biofilm formed by S.epidermidis.

development of bacterial biofilm

Enterococcus faecalis

Enterococcus faecalis
SEM

Enterococcus faecalis
micrograph

Multispecies bacterial biofilms

Scanning electron microscopy of non-surface-attached bacterial biofilm (S.aureus, S.epidermidis and P.aeruginosa).

Multispecies bacterial biofilm formed by S.aureus, S.epidermidis and P.aeruginosa.

Multispecies bacterial biofilm formed by S.aureus, S.epidermidis and P.aeruginosa.

Multispecies bacterial biofilm formed by S.aureus, S.epidermidis and P.aeruginosa.

Multispecies bacterial biofilm formed by S.aureus, S.epidermidis and P.aeruginosa.

Biofilm formed by
S.aureus and P.aeruginosa.

Multispecies bacterial biofilm
S.aureus, P.aeruginosa, Bacillus sp.. Arrows indicate extracellular polymeric substance (EPS).

Why are microbial biofilms so important?

Biofilms have been found to be involved in a wide variety of microbial infections in the body, by one estimate 80% of all infections. Infectious processes in which biofilms have been implicated include common problems such as urinary tract infections, catheter infections, middle-ear infections, formation of dental plaque, gingivitis, coating contact lenses, and less common but more lethal processes such as endocarditis, infections in cystic fibrosis, and infections of permanent indwelling devices such as joint prostheses and heart valves.
Text: Wikipedia
References

[1] Otto M. Staphylococcal Biofilms. Curr Top Microbiol Immunol. 2008 ; 322: 207228.

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