Beta-lactamases with high activity against imipenem and Sch 34343 from Aeromonas hydrophila.

Two groups of inducible beta-lactamases were found among nine isolates of Aeromonas hydrophila. Five isolates produced enzymes with high activity against the penem Sch 34343 and the carbapenem imipenem: the enzymes from some of these isolates also had activity against penicillin, ampicillin, carbenicillin, cephaloridine and cephalexin but one isolate produced an enzyme with no detectable activity against cephalosporins. The other four isolates produced typical 'cephalosporinases' with activity against cephaloridine and cephalexin but not against cefuroxime, cefotaxime, penicillins, imipenem or Sch 34343.