Question

Which is a reason for antimicrobial resistance being higher in a biofilm than in free-floating bacterial cells?

a) Enhanced DNA repair mechanisms
b) Limited antibiotic penetration
c) Increased mutation rate
d) Altered plasmid transfer

Answer 1

Bacteria in biofilms show increased resistance to antibiotics due to limited antibiotic penetration, phenotypic changes, and altered plasmid transfer.

Step-by-step explanation:

Bacteria in biofilms often show increased resistance to antibiotics compared to free-floating bacteria because of several reasons:

1. Limited antibiotic penetration: The extracellular polymeric substance (EPS) in biofilms can slow the diffusion of antibiotics, preventing them from reaching cells in deeper layers of the biofilm.
2. Phenotypic changes: Bacterial cells in biofilms may exhibit increased production of efflux pumps, which actively extrude antibiotics out of the cells, contributing to antibiotic resistance.
3. Altered plasmid transfer: Biofilms provide an ideal environment for the exchange of extrachromosomal DNA, including antibiotic resistance genes, through horizontal gene transfer.

These factors contribute to the higher antimicrobial resistance observed in biofilms compared to free-floating bacterial cells.