on-level-consequence-regarding-carbapenem-resistance-encoded-on-the-same-plasmid

Question

A plasmid carries genes for resistance to tetracycline, penicillin (via a beta-lactamase), and a carbapenemase. If a clinician prescribes tetracycline, what is the most likely population-level consequence regarding carbapenem resistance encoded on the same plasmid?

Accepted Answer

Use of tetracycline will co-select for the entire plasmid, increasing the frequency of carbapenem resistance in the population even though carbapenems were not used.

Answer

Carbapenem resistance will decline because tetracycline induces a plasmid loss mechanism that specifically cures plasmids with beta-lactamase genes while leaving other resistance determinants unaffected.

Answer

Tetracycline use will only select for tetracycline resistance and will actively reduce any carbapenem resistance because carbapenemase expression is repressed when tetracycline is present.

Answer

Resistance dynamics are unaffected because co-selection requires simultaneous administration of all antibiotics encoded on the plasmid; single-drug exposure cannot drive selection for unrelated resistance genes on the same element.