Biofilm Formation and Clinical Significance

1. What is a biofilm? A. A free-floating bacterial cell
B. A colony of viruses
C. A complex community of microorganisms adhering to a surface
D. A type of antibiotic

Explanation: Biofilms are structured communities of microbial cells surrounded by a self-produced polymeric matrix attached to a surface.

2. Which is the primary component of the biofilm matrix? A. Lipids
B. Proteins
C. Extracellular polymeric substances (EPS)
D. DNA only

Explanation: EPS, composed of polysaccharides, proteins, lipids, and nucleic acids, forms the bulk of the biofilm matrix.

3. Which is NOT a typical site of biofilm formation in the human body? A. Teeth
B. Lungs
C. Heart valves
D. Brain tissue

Explanation: Biofilms commonly form on surfaces like teeth, catheters, heart valves, and lungs, but not typically in brain tissue.

4. The dental plaque on teeth is an example of: A. A viral infection
B. A protozoan infection
C. A biofilm
D. A fungal colony

Explanation: Dental plaque is a biofilm formed by bacteria adhering to the tooth surface.

5. Why are biofilms clinically significant? A. They enhance wound healing
B. They improve drug delivery
C. They increase resistance to antibiotics and immune clearance
D. They prevent microbial growth

Explanation: Biofilms protect microbes from antibiotics and immune cells, leading to persistent infections.

6. Which of the following is NOT a stage of biofilm formation? A. Initial attachment
B. Maturation
C. Sporulation
D. Dispersion

Explanation: Sporulation is not a standard stage of biofilm development.

7. Which gene regulation system is commonly involved in biofilm formation? A. CRISPR-Cas
B. Operon lac
C. Quorum sensing
D. tRNA synthetase

Explanation: Quorum sensing allows bacteria to coordinate biofilm formation based on population density.

8. Which organism is famous for forming biofilms in cystic fibrosis lungs? A. Streptococcus pneumoniae
B. Pseudomonas aeruginosa
C. Escherichia coli
D. Clostridium difficile

Explanation: P. aeruginosa forms persistent biofilms in CF patients' lungs.

9. Infections associated with medical devices are typically due to: A. Urinary tract infections
B. Skin infections
C. Surgical site infections
D. Device-related infections (e.g., catheters)

Explanation: Indwelling devices are common biofilm sites.

10. How do biofilms contribute to antibiotic resistance? A. By producing their own antibiotics
B. By mutating rapidly
C. By blocking antibiotic penetration and harboring dormant cells
D. By increasing host immunity

Explanation: Biofilm EPS blocks antibiotics, and dormant cells resist treatment.

11. Which method is used to detect biofilms? A. Gram staining
B. PCR
C. Confocal laser scanning microscopy
D. Blood culture

Explanation: Confocal microscopy helps visualize biofilm structure.

12. Which enzyme can degrade biofilms? A. DNase
B. Ligase
C. DNA polymerase
D. Kinase

Explanation: DNase breaks down extracellular DNA in biofilms.

13. Biofilms are associated with: A. Acute infections
B. Self-limiting infections
C. Chronic and relapsing infections
D. Allergic reactions

Explanation: Biofilms cause chronic infections due to resistance mechanisms.

14. Which fungus forms biofilms on catheters? A. Candida albicans
B. Aspergillus fumigatus
C. Cryptococcus neoformans
D. Trichophyton rubrum

Explanation: Candida albicans forms biofilms on medical devices.

15. Which surface is LEAST likely to support biofilm growth? A. Rough plastic
B. Stainless steel
C. Glass
D. Continuously sheared, highly mobile surfaces

Explanation: High shear environments discourage adhesion.

16. Which bacterium is associated with biofilms in endocarditis? A. Neisseria gonorrhoeae
B. Staphylococcus aureus
C. Helicobacter pylori
D. Vibrio cholerae

Explanation: S. aureus forms biofilms on heart valves causing endocarditis.

17. Which immune response is most commonly evaded by biofilms? A. Antibody production
B. Phagocytosis
C. T cell activation
D. Interferon response

Explanation: Biofilms block access to phagocytes.

18. What is "dispersion" in biofilm formation? A. Breakdown of antibiotics
B. Bacteria detach and spread
C. EPS production
D. Death of biofilm cells

Explanation: Dispersion allows colonization of new sites.

19. What can trigger biofilm dispersion? A. Nutrient depletion
B. High oxygen
C. DNA mutation
D. Immune cell presence

Explanation: Starvation induces bacteria to leave the biofilm.

20. Which is a potential anti-biofilm strategy? A. Bacteriostatic agents only
B. Targeting EPS matrix degradation
C. Only increasing host immunity
D. Allowing natural clearance

Explanation: EPS disruption and quorum sensing interference are strategies.

21. What role does extracellular DNA (eDNA) play in biofilms? A. Nutritional source
B. Structural stability
C. Gene transfer
D. All of the above

Explanation: eDNA is multifunctional in biofilm stability and survival.

22. Which bacterium forms biofilms in the urinary tract? A. Klebsiella pneumoniae
B. Escherichia coli
C. Salmonella typhi
D. Bacillus anthracis

Explanation: Uropathogenic E. coli forms biofilms in UTIs.

23. In hospitals, biofilms contribute to: A. Staff burnout
B. Nosocomial infections
C. Medical education
D. Equipment calibration

Explanation: Biofilms are a common source of hospital-acquired infections.

24. Which environment favors biofilm formation? A. High turbulence
B. Nutrient-rich stagnant surfaces
C. Dry environments
D. UV exposure

Explanation: Bacteria thrive in moist, nutrient-rich conditions.

25. Which clinical approach is most effective against biofilm infections? A. Monotherapy with antibiotics
B. Surgical removal of infected device + antibiotics
C. Waiting for immune clearance
D. Antiviral therapy

Explanation: Removal of colonized devices is often necessary for effective treatment.