<prompt> Extended spectrum beta lactamases ESBLs are characterized by activity against all except.PenicillinasesCephalosporinasesOxyimino-cephalosporinasesCarbapenems  <response>: Ans. D CarbapenemsRef: Katzung 10e p739Carbapenems like imipenem are the only beta lactams reliably efficacious against ESBL producing bacteria. 