National epidemiologic surveys of Enterobacter aerogenes in Belgian hospitals from 1996 to 1998

Two national surveys were conducted to describe the incidence and prevalenc e of Enterobacter aerogenes in 21 Belgian hospitals in 1996 and 1997 and to characterize the genotypic diversity and the antimicrobial resistance prof iles of clinical strains off. aerogenes isolated from hospitalized patients in Belgium in 1997 and 1998. Twenty-nine hospitals collected 10 isolates o f E. aerogenes, which were typed by arbitrarily primed PCR (AP-PCR) using t wo primers and pulsed-field gel electrophoresis, MICs of 10 antimicrobial a gents were determined by the agar dilution method. Beta-lactamases were det ected by the double-disk diffusion test and characterized by isoelectric po int. The median incidence of E. aerogenes colonization or infection increas ed from 3.3 per 1,000 admissions in 1996 to 4.2 per 1000 admissions in the first half of 1997 (P < 0.01), E. aerogenes strains (n = 260) clustered in 25 AP-PCR types. Two major types, BE1 and BE2, included 36 and 38% of strai ns and were found in 21 and 25 hospitals, respectively. The BE1 type was in distinguishable from a previously described epidemic strain in France. Half of the strains produced an extended-spectrum betalactamase, either TEM-24 tin 86% of the strains) or TEM-3 tin 14% of the strains). Over 75% of the i solates were resistant to ceftazidime, piperacillin-tazobactam, and ciprofl oxacin, Over 90% of the strains were susceptible to cefepime, carbapenems, and aminoglycosides. In conclusion, these data suggest a nationwide dissemi nation of two epidemic multiresistant E. aerogenes strains in Belgian hospi tals. TEM-24 beta-lactamase was frequently harbored by one of these epidemi c strains, which appeared to be genotypically related to a TEM-24-producing epidemic strain from France, suggesting international dissemination.