Prevalence characterization of extended‐spectrum β‐lactamases among Escherichia coli isolates collected in Zhengzhou

Objectives: To determine the prevalence and the diversity of extended-spectrum β-lactamases (ESBLs) among Escherichia coli isolates in Zhengzhou, China. Methods: Clinical isolates were collected and investigated from the first affiliated hospital of Zhengzhou University and its associated health-care facilities in Zhengzhou, China, during the period from January 2006 to June 2008. Antibiograms were performed on Mueller–Hinton agar plates with the disc-diffusion method and MICs were determined by the agar-dilution method. Total DNA was extracted with a Qiagen mini kit and screened by PCR. Results: Of 94 nonduplicate ESBL-positive isolates, TEM-type was encoded in 74 and 79% of the ESBL isolates. Fifty-six isolates were SHV type ESBLs. CTX-M-1, CTX-M-14, CTX-M-25, and CTX-M-38 types were encoded in 30, 54, 6, and 4, respectively. OXA-1-type β-lactamases were encoded in six and OXA-20-type was encoded in two isolates. Conclusions: We describe a complex ESBL epidemiology. The study revealed a high rate of ESBL-producing E. coli isolates. TEM and CTX-M enzymes dominated in ESBL-positive E. coli isolates in Zhengzhou, China. J. Clin. Lab. Anal. 23:404–407, 2009. © 2009 Wiley-Liss, Inc.