Answer
The extracellular polymeric substances which constitute the biofilm's protective layer manage to inhibit the effectiveness of antibiotics, as the bacteria within such layers have lower growth rates which makes certain antibiotics less effective in targeting them. Furthermore, the bacteria within these biofilms have been able to undergo physiological changes which have activated mechanisms that can resist antibiotic treatments.
Work Step by Step
1. Biofilms are sticky layers formed by bacteria which adhere in clumps to a surface (e.g. a medical device such as a catheter).
2. The formation of the biofilm involves a matrix of extracelluar polymetric substances, chiefly polysaccharides and proteins.
3. The resultant biofilm forms a protective layer for the bacteria, which would be more vulnerable as single plankton to antibiotics.
4. Thus protected, the bacteria do not have such high growth rates, and as certain antibiotics target bacteria on the basis of growth rate, this renders them less effective.
5. The corralled bacteria are also able to activate resistance mechanisms that they cannot as single plankton, and these mechanisms are imperfectly understood at present, making them more resistant to antibiotics as a consequence.
