title: Characterization of beta-lactam-resistant Klebsiella oxytoca isolated in a neonatal intensive care unit.
abstract: The occurrence of Klebsiella oxytoca resistant to ampicillin, piperacillin, aztreonam and cefuroxime in a neonatal intensive care unit, including two cases of septicemia, was shown to consist of a spread on three consecutive occasions caused by three different biochemical Klebsiella oxytoca phenotypes. All isolates, except six surface isolates from one infant belonging to phenotype 1, were sensitive to cefotaxime (MIC 0.5-4 mg/l) and ceftazidime (MIC 0.25-1 mg/l). Isolates of phenotypes 1 and 2 produced a beta-lactamase with an isoelectric point of 5.5 and isolates of phenotype 3, a beta-lactamase with an isoelectric point of 7.9. The beta-lactamases of all three phenotypes hydrolysed benzylpenicillin and more slowly cephalothin. All phenotype 1 isolates carried a 2.9 Md plasmid and most isolates also a 36 Md plasmid. All phenotype 2 isolates carried a 4.8 Md plasmid and one isolate also a 30 Md plasmid. The phenotype 3 isolates carried only one 85 Md plasmid.
authors.affiliation: Department of Clinical Microbiology, Karolinska Hospital, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Jalakas-Pörnull
authors.forename: K
authors.initials: K
authors.lastname: Dornbusch
authors.forename: I
authors.initials: I
authors.lastname: Kühn
authors.forename: U
authors.initials: U
authors.lastname: Ransjö
authors.forename: C
authors.initials: C
authors.lastname: Jonsson
authors.forename: U
authors.initials: U
authors.lastname: Broberger
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D007525:Isoelectric Focusing; D007709:Klebsiella / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D010957:Plasmids; D012703:Serotyping; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D047090:beta-Lactams