Outbreak of extended-spectrum β-lactamase VEB-1-producing isolates of Acinetobacter baumannii in a French hospital

Twelve clonally related and multidrug-resistant Acinetobacter baumannii isolates were recovered during a 4-month period from 12 patients hospitalized at the Valenciennes Hospital in France. Antibiograms determined by the double-disk diffusion technique on cloxacillin-containing plates detected a clavulanic acid-inhibited extended-spectrum beta-lactamase (ESBL). PCR and sequencing identified the gene encoding the Ambler class A ESBL VEB-1. This gene was located on the chromosome and was part of a class I integron identical to that previously identified in Pseudomonas aeruginosa isolates from Thailand. Additionally, seven clonally related bla(VEB-1)-positive A. baumannii strains were identified in the immediate environment of the hospitalized patients. This is the first report of the ESBL VEB-1 in Acinetobacter spp. and the first description of VEB-1-producing strains as a source of an outbreak occurring outside Southeast Asia. This report underlines the difficulty of the identification of ESBLs in A. baumannii.