Objective: To survey the frequency of blaTEM, blaSHV and blaCTX-M genotypes in extended-spectrum b-lactamase (ESBL)-producing Escherichia coli (E. coli) isolated from hospitalized patients with urinary tract infection and the determination of their antibiotic resistance patterns. Methods: During 11-month study, 100 ESBL-producing E. coli were collected from 330 patients who met the definition of urinary tract infection. The phenotypic identification of ESBL was confirmed by double disk synergy test and combined disk diffusion test. In vitro, susceptibility to ESBL isolates than 14 antimicrobial agents was performed by Kirby-Bauer disk diffusion method. The frequency of blaTEM, blaSHV and blaCTX-M ESBL-producing E. coli was assessed by PCR method. Results: The frequency of ESBL-producing E. coli was 40.8%. In vitro, susceptibility to ESBL-producing E. coli showed that the majority of isolates were highly susceptible to amikacin (74%) and imipenem (91%). The rates of resistance to other antibiotics varied from 33% to 96%. Through 100 tested isolates, the prevalence of blaTEM, blaSHV and blaCTX-M genes was determined to be 67%, 45% and 74% respectively. In comparison with other bla genes, the frequency of blaCTX-M was strikingly high. Conclusions: Due to the increase of E. coli with multiple ESBL genes, continuous sur-veillance in order to use appropriate antibiotics and the control of infections is necessary.
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