Consider the following statements : 1. Biofilms can form on medical implants within human tissues. 2. Biofilms can form on food and food processing surfaces. 3. Biofilms can exhibit antibiotic resistance. Which of the statements given above are correct ?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3 ✓ UPSC's answer

Why the answer is (d)

• A biofilm is a community of microorganisms attached to a surface and embedded in a self-produced slimy matrix.

• Statement 1 is correct: biofilms form on catheters, heart valves, joint implants and dental plaque, causing persistent infections.

• Statement 2 is correct: they form on food-processing equipment and on foods themselves, harbouring pathogens like Listeria and Salmonella.

• Statement 3 is correct: the matrix and the altered metabolism of cells within it make biofilm bacteria up to 1,000 times more resistant to antibiotics and disinfectants than free-floating cells.

• Hence 1, 2 and 3, option (d).

Why the other options are wrong

(a) 1 and 2 only: Statement 3 on antibiotic resistance is also correct.
(b) 2 and 3 only: Statement 1 on implants is also correct.
(c) 1 and 3 only: Statement 2 on food surfaces is also correct.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.