A chronic Pseudomonas aeruginosa lung infection exhibits increasing antibiotic resistance after repeated treatment cycles. Which mechanism explains this acquired resistance in a biofilm due to horizontal gene transfer?

💡 Explanation

Antibiotic treatment acts as a selection pressure. Because bacteria with efflux pump mutations that reduce antibiotic accumulation survive and proliferate through horizontal gene transfer, therefore, the biofilm develops increased resistance, rather than solely through changes in quorum sensing, capsule production, or respiration.

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