Molecular diversity of Proteus mirabilis isolates producing extended-spectrum β-lactamases in a French university hospital


Corresponding author and reprint requests: M. Biendo, Laboratoire de Bactériologie et Hygiène, CHU Nord, Place V, Pauchet, 80054 Amiens cedex 1, France


Between February 1997 and December 2002, 3340 hospitalised patients yielded samples positive for Proteus mirabilis, of whom 45 (1.3%) were colonised/infected by P. mirabilis producing extended-spectrum β-lactamases (ESBLs). The gross incidence of patients colonised/infected by ESBL-producing P. mirabilis was 1.61/105 days of hospitalisation, with 20% of isolates being collected from patients in urology wards, most frequently (53.3%) from urine samples. Seventeen (37.7%) of the 43 isolates were obtained from samples collected within 48 h of hospitalisation, indicating that they were community-acquired. Isoelectric focusing assays and sequencing identified the TEM-24, TEM-92 and TEM-52 ESBLs. Pulsed-field gel electrophoresis revealed eight pulsotypes (I–VIII), with the two most common pulsotypes, IV and VI, comprising ten (23.3%) and 12 (26.6%) isolates, respectively. These pulsotypes were considered to represent epidemic strains and spread in various wards of the hospital.