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

Fifty-two strains of Klebsiella pneumoniae producing an AmpC-type plasmid-m ediated beta-lactamase were isolated from 13 patients in the same Intensive care unit between March 1998 and February 1999. These strains were resista nt to ceftazidime, cefotaxime and ceftriaxone. but susceptible to cefoxitin , cefepime and aztreonam. Plasmid content and genomic DNA restriction patte rn 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 s equence PCR products obtained from two unrelated strains of Hafnia alvei. O ur results show that the ACC-1 beta-lactamase was derived from the chromoso me-encoded AmpC-type enzyme of H. alvei. (C) 2000 Federation of European Mi crobiological Societies. Published by Elsevier Science B.V. All rights rese rved.