title: Characterization of two clinical, multiple-drug-resistant isolates of Enterobacter cloacae.
abstract: Two multiple drug resistant Enterobacter cloacae isolates (Nos. 460 and 493) varied phenotypically in bacteriocin susceptibility in the absence of significant O antigen variation. Both isolates were susceptible to chloramphenicol, nitrofurantoin, polymyxin B, nalidixic acid, norfloxacin, and enoxacin only. One isolate carried a non-conjugative resistance (R) plasmid, whereas the other isolate contained a conjugative, 'curable' R plasmid and a cryptic plasmid. Both wild-type isolates constitutively produced a chromosomal cephalosporinase (nitrocefin hydrolysis); 'cured' variants of E. cloacae isolate No. 493, which had become susceptible for lamoxactam, produced a cefazolin-inducible beta-lactamase. The two E. cloacae isolates, including their 'cured' variants, were of low-grade virulence for outbred NMRI mice. Both isolates differed somewhat in susceptibility to defibrinated human blood. Inhibitory (0.25 microgram/ml), but not subinhibitory (0.125 microgram/ml) concentrations of norfloxacin and enoxacin combined with human blood yielded additive effects against both E. cloacae isolates.
mesh_terms: D000328:Adult; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000032:analysis; D001430:Bacteriocins; D001770:Blood Bactericidal Activity; D002510:Cephalosporinase / Q000378:metabolism; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D004587:Electrophoresis, Agar Gel; D015365:Enoxacin; D004754:Enterobacter / Q000145:classification* / Q000187:drug effects / Q000472:pathogenicity; D004755:Enterobacteriaceae / Q000145:classification*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D009268:Nalidixic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D009287:Naphthyridines / Q000494:pharmacology; D009643:Norfloxacin; D019081:O Antigens; D011815:R Factors; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001430:Bacteriocins; D004269:DNA, Bacterial; D009287:Naphthyridines; D019081:O Antigens; D015365:Enoxacin; D009268:Nalidixic Acid; D002510:Cephalosporinase; D009643:Norfloxacin