- Bacteria frequently form biofilms, which are groups of microorganisms that attach to surfaces and produce an extracellular matrix. Over 99% of bacteria exist in biofilms. - Biofilms provide bacteria protection from environmental threats like antibiotics. The extracellular matrix restricts antibiotic penetration and biofilms can be up to 1000 times more resistant to antibiotics than planktonic bacteria. - Biofilm formation involves an initial attachment phase, followed by growth of colonies on the surface and eventual detachment of planktonic cells to form new biofilms elsewhere.

1. Biofilms
- Dr. Richa
PMCH, Patna
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2. INTRODUCTION
 A biofilm is any group of microorganisms in which
cells stick to each other and often also to a surface.
 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.
 These adherent cells are frequently embedded within a
self-produced matrix of extracellular polymeric
substance (EPS). Biofilm EPS, which is also referred to as
"slime," is a polymeric jumble of DNA, proteins and
polysaccharides.
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3. Why do bacteria live in biofilms?
 By the present knowledge more than 99% of the bacteria in
nature live in biofilms.
 In 80% of the chronic diseases biofilms are suggested to play an
important role.
 Biofilm provides safe habitat against environmental challenges
like host defense and antibiotics.
 The ECM restricts the penetration of antibiotics by diluting and
binding them before they can reach deeper areas.
 If the ECM is thin, most of the bacteria will be sacrificed to
produce a barrier biomass protecting deeper layers.
 Genetic antibiotic resistance is distributed widely in the colony by
horizontal gene transfer.
Up to 1,000 times more resistant than the same bacteria not growing in a
biofilm.
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4. Properties of Biofilms
 Several bacterial or fungal species can live together in the
same biofilm.
 Between the surface and deep layers of the biofilm a
gradient in the oxygen level exists and deepest may be
anaerobic.
 The microbes are more active in the surface, however on
the deeper layers their metabolic activity and cell division
are decreased.
 In a thick biofilm a water channel system provides
distribution of oxygen and nutrients.
 Cell to cell communication exists within the biofilm via
signaling molecules. This communication is known as
Quorum Sensing.
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5. BIOFILM –FORMATION &
DEVELOPMENT
Biofilm formation is typically described in three
stages:
(i) attachment
(ii) growth of colonies
(iii) detachment of planktonic organisms
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6. ATTACHMENT
• The formation of a biofilm begins with the
attachment of free-floating microorganisms
to a surface.
• It is thought that the first colonist bacteria of
a biofilm adhere to the surface initially
through weak, reversible adhesion via van
der Waals forces and hydrophobic effects.
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7. GROWTH OF COLONIES
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8. DETACHMENT AND RELEASE OF
PLANKTONIC CELLS
• A mature biofilm can remain sessile for long periods.
• When suitable conditions arise, the biofilm activates
and bacteria seeds to other locations to form new
biofilms.
• Dispersal may happen either in planktonic form or in
bacterial clusters.
• Enzymes that degrade the biofilm extracellular
matrix, such as dispersin B and deoxyribonuclease,
may play a role in biofilm dispersal.
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9. Bacteria forming biofilms
1. E.coli
2. P. aeruginosa
3. S. epidermidis
4. S. aureus
5. K. pneumoniae
6. Actinomyces
7. H. influenza
8. Bacillus
9. Pneumococcus
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10. Biofilms in Otolaryngologic
Diseases
In the field of otolaryngology, biofilms have been reported in:
• OTITIS MEDIA WITH EFFUSION
• CHOLESTEATOMA
• ADENOTONSILLAR DISEASES
• RHINOSINUSITIS
• PROSTHETIC DEVICES: TRACHEOTOMY AND
TYMPANOSTOMY TUBES AND COCHLEAR IMPLANTS.
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11. Otitis Media
• Observations have raised the possibility that OME
and recurrent OM may be biofilm diseases.
• Cultures of aspirated fluid are often sterile when
bacterial DNA and RNA can be retrieved from the
specimens via PCR.
• This suggests presence of bacteria in the middle ear
fluids despite the inability to culture them.
• Bacterial biofilms have been observed by direct
microscopy from middle ear mucosa in
experimentally induced H. influenzae otitis media.
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12. Cholesteatoma
• In chronic ear infections the role of biofilms seems to be
very important.
• Mastoid mucosal biofilm has been found in patients with
COM.
• In Chronic middle ear infections, the presence of biofilm
was found more often in patients with cholesteatoma than
with patients without cholesteatoma.
• Furthermore, the constant inflammation due to bacterial
products from within the biofilm can play a role in the bony
destruction seen in cholesteatoma.
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13. Biofilms in adenoids and tonsils
• Chronic adenotonsillar infection and/or hypertrophy are
thought to be caused by multiple and sometimes resistant
bacteria.
• There are several studies showing biofilms can be found in
adenoids and tonsils and especially in the crypts of tonsils.
• Toretta et al demonstrated the presence of tonsillar biofilm in
children with recurrent exacerbations of chronic tonsillar
infections and suggested that tonsillar size is an important
indicator of the presence of tonsillar biofilm.
• The mechanical debridement of the nasopharyngeal biofilms
may explain the observed clinical benefit associated with
adenoidectomy in subsets of pediatric patients. 13

14. Chronic Rhinosinusitis
• Cryer and colleagues were the first to report bacterial
biofilms in the sinus mucosa of patients with
Pseudomonas aeruginosa infection and CRS.
• Epithelial inflammation causing defective mucociliary
clearance and accumulation of secretion is the
fundamental pathophysiology of CRS. A continuously
irritating factor like bacterial biofilm could easily cause
CRS.
• Biofilms may be accountable, but a direct evidence of
these being a causative factor in CRS is still lacking.
• But definitely CRS with biofilms are associated with more
severe disease preoperatively and worse postoperative
outcomes after endoscopic sinus surgery.
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15. BIOMATERIAL INFECTIONS
• Implant associated biofilm infection results from interaction
between implant, bacteria and host.
• Attachment of bacteria to implant occurs via non-specific factors
like surface roughness, tension, hydrophobicity and electrostatic
forces.
• Biofilms can be formed on different materials ranging from
silicone to titanium.
• Persistent inflammation and recurrent infection after the insertion
of tympanostomy tube may be caused by persistent bacterial
biofilms.
• Biofilms can also be found on ossicular chain prostheses in
patients.
• Cochlear implants removed because of persistent infection have
also been shown to have anatomical evidence of biofilms.
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16. INVOLVEMENT IN OTHER
DISEASES AND DAILY LIFE
Include common problems such as bacterial
vaginosis, urinary catheter infections, middle-ear
infections, formation of dental plaque,gingivitis,
coating contact lenses .
• 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. 16

17. Detection of Biofilm-
Investigations
• Biofilms can be detected by scanning electron
microscopy(SEM).
• Currently Fluorescent in situ hybridization (FISH)/
Confocal Scanning Laser Microscopy(CSLM) is
accepted as a gold standard for detection of biofilms.
CSLM is used to detect the biofilms and FISH to
identify pathogens.
• Basically the diagnosis is made when a community of
viable microbes covered with ECM is visualized.
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18. An image from an scanning electron microscope of a
Staphylococcus aureus biofilm on a vascular prosthesis.
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19. Confocal laser scanning microscopy images of biofilms
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20. Treatment of Biofilms
• The MBEC is 4 to 500 folds higher for biofilms than MIC of same
bacteria in planktonic form. So systemic treatment may require
intolerable high concentrations or may not be effective at all.
• Also surgical removal of all infected mucosa is seldom possible.
• Thus, several approaches need to be used simultaneously.
• Basically 3 strategies exist:
• Topical antibiotic treatment
• Biofilm detachment using surfactants, irrigation and surgery
• Freeing bacteria from biofilm
• Degrading the matrix by enzymes like alginase
• Promoting a bacterial phenotype shift from sessile to planktonic
form with Quorum sensing inhibitors (QSI) like plant
furanones. 20

21. • Alandejani et al reported that honey was effective against S.
aureus and P. aeruginosa biofilms in vitro.
• Jass and Lappin-Scott found that low levels of electrical
currents can enhance antibiotic efficacy against biofilms.
• Krespi et al revealed a nonpharmacological treatment
method for (MRSA) biofilm disruption and killing using 2
different lasers.
• Iron inhibits the expression of certain genes essential for
biofilm production. Since these iron salts are well tolerated
biologically and inhibit biofilms at low concentrations they
may be an efficient way of treating biofilm diseases in vivo
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22. • Above all, preventive measures have a high value.
• Biofilms can be prevented by vaccination against
organisms that tend to cause chronic infections
such as pneumococci.
• Antibiotic prophylaxis or early aggressive antibiotic
therapy can also be seen as a biofilm prevention.
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