Outbreak ofKlebsiella pneumoniaeproducing transferable AmpC-type β-lactamase (ACC-1) originating fromHafnia alvei

Abstract

Fifty-two strains of Klebsiella pneumoniae producing an AmpC-type plasmid-mediated β-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 β-lactamases were identified, TEM-1 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 β-lactamase was derived from the chromosome-encoded AmpC-type enzyme of H. alvei.