Which failure mode becomes likely when an antibiotic drug concentration gradient exists within a bacterial biofilm due to outer membrane porin mutation?

💡 Explanation

Efflux pump expression increases due to selective pressure from the drug gradient in the biofilm; because the mutation reduces antibiotic entry, bacteria with higher efflux survive better. Therefore, efflux pump amplification is likely, rather than immediate lysis or reduced transduction, which have different causes.

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