Regarding bacterial efflux and influx pumps and antibiotic resistance, which statement is the EXCEPTION (does not promote resistance)?

Correct answer: B. Upregulation of influx pumps increases antibiotic entry, increasing susceptibility (not resistance)

• A. This is true — efflux pump activity removing antibiotics from the cell is a well-established resistance mechanism.
• B. Correct (the exception). Upregulating influx pumps actually brings MORE antibiotic INTO the cell, which would increase (not decrease) bacterial susceptibility — the opposite of conferring resistance.
• C. This is true — decreased drug influx (less entry) is a recognized resistance mechanism.
• D. This is true — efflux pump overexpression is one of the most common antibiotic resistance mechanisms.

Note: Efflux pumps → remove antibiotics from the cell → RESISTANCE. Influx pumps → bring antibiotics INTO the cell → increased SUSCEPTIBILITY.