| ampicillin | <drug> Penicillin derivative with broad spectrum activity, ampicillin resistance is often used as a marker for plasmid transfer in genetic engineering (for example pBR322 is ampicillin resistant). (13 Nov 1997) |
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| ampicillin resistance | Nonsusceptibility of a microbe to the action of ampicillin, a penicillin derivative that interferes with cell wall synthesis. (12 Dec 1998) |