Which of the following is a property of biofilms and is of clinical signifcance?

 Which of the following is a property of biofilms and is of clinical signifcance?

a. Facilitate stain formation.

b. Increase sensitivity to antibiotics.

c. Extremely tolerant of antimicrobial agents.

d. Enhance the development of halitosis.

The correct answer is C. Extremely tolerant of antimicrobial agents.

The term biofilm describes relatively undefinable microbial community associated with a tooth surface or any other hard non-shedding material. Biofilms are ubiquitous and are found in oral cavity, the bottom of boats and docks, inside pipes, rocks in streams, catheters, hip and voice prosthesis and contact lenses.

Biofilm bacteria exhibit stronger resistance (1000 to 1500 times) to biocides and antimicrobial agents than do their planktonic counterpart. Following hypothesis may help to explain the increased resistance to antimicrobials.

1. The exopolysaccharide of the biofilm matrix may inhibit the diffusion of antimicrobial agents.

2. The physiological differences among biofilm bacteria leave only a part of biofilm bacteria susceptible to growth dependent antibiotics.

3. The genetic changes occurring in transition from planktonic to biofilm bacteria make the biofilm bacteria insensitive to various biocides and antimicrobial agents.

4. Slower rate of growth of organisms due the nutrient limitation may also contribute to the resistance to antimicrobial agents by biofilm bacteria. 

5. Extracellular enzymes such as β–lactamase, formaldehyde dehydrogenase become concentrated in extracellular matrix, thus inactivating some antibiotics.

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