Biofilms are structured communities of bacteria enclosed in a self-produced extracellular matrix. They enhance microbial survival by:
- Protecting against antibiotics
- Evading host immune responses
- Facilitating persistent, recurrent infections
Clinical Relevance
Biofilm formation is a key virulence factor in device-related infections, chronic infections, and recurrent inflammation.
Important Biofilm-Producing Organisms
| Organism | Site of Biofilm Formation | Associated Disease/Condition |
|---|---|---|
| Staphylococcus epidermidis | Catheters, prosthetic devices | Infections of catheters, prosthetic joints, and prosthetic heart valves |
| Viridans streptococci (S. mutans, S. sanguinis) | Dental enamel, heart valves | Dental caries (plaques), infective endocarditis |
| Pseudomonas aeruginosa | Respiratory tract, contact lenses | Chronic colonization in cystic fibrosis, ventilator-associated pneumonia, contact lens–associated keratitis |
| Nontypeable (unencapsulated) Haemophilus influenzae | Upper respiratory tract | Otitis media, sinusitis |
Learning Objective (USMLE Step 1): Recognize major biofilm-producing bacteria, their sites of colonization, and the clinical syndromes they cause—particularly in device-associated and chronic infections.
