Outbreak of Klebsiella pneumoniae producing transferable AmpC-type β-lactamase (ACC-1) originating from Hafnia alvei

Fifty-two strains of Klebsiella pneumoniae producing an AmpC-type plasmid-mediated beta-lactamase were isolated from 13 patients in the same Intensive care unit between March 1998 and February 1999. These strains were resistant to ceftazidime, cefotaxime and ceftriaxone. but susceptible to cefoxitin, cefepime and aztreonam. Plasmid content and genomic DNA restriction pattern analysis suggested dissemination of a single clone. Two beta-lactamases were identified, TEM-I and ACC-1. We used internal bla(ACC-1) primers, to sequence PCR products obtained from two unrelated strains of Hafnia alvei. Our results show that the ACC-1 beta-lactamase was derived from the chromosome-encoded AmpC-type enzyme of H. alvei. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.