High Frequency of Extended-Spectrum beta-Lactamase-Producing Klebsiella pneumoniae and Escherichia coli Isolates From Male Patients' Urine

Background: The number of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae reported cases all over the world has continued to increase faster than the other resistance mechanisms, particularly in E. coli and K. pneumoniae. Objectives: This cross-sectional study was designed to assess the prevalence of multidrug resistance of ESBL-producing urine isolates of E. coli and K. pneumoniae collected in Tehran hospitals, as well as the molecular characterizations of some ESBL genes, with an emphasis on occurrence rates by sex. Materials and Methods: A total of 190 E. coli and K. pneumoniae isolates were collected from patients' urine samples in hospitals from Tehran, Iran during 2009 -2010, and were screened for antibiotic susceptibility, ESBL phenotype, and presence of bla(CTX-M) and bla(TEM) genes. Minimal inhibitory concentration (MIC) for ceftazidime and cefotaxime were made by agar dilution method. Results: The ESBL phenotype was detected in 55.5% of E. coli and 46.4% of K. pneumoniae isolates. Presence of bla(CTX-M-1) was dominant in both organisms. The prevalence of bla(CTX-M-1) carrying isolates among ESBL-producing K. pneumoniae and E. coli isolates were 49.1% and 85.7%, respectively. Among ESBL-producing isolates, 68.5% of E. coli and 59.3% of K. pneumoniae isolates carried the bla(TEM) genes, and simultaneous carrying of blaCTX-M and bla(TEM) genes was observed in 68.5% of E. coli and 33.3% of K. pneumoniae isolates. The resistant rate to ceftazidime, cefotaxime, and cefepime was significantly higher in K. pneumoniae and E. coli isolates from male patients urine samples. A significant higher rate of bla(CTX-M-1), bla(TEM), and co-bla(CTX-M)-1-bla(TEM) genes were seen for E. coli and K. pneumoniae isolates in male patients' urine. Conclusions: The results indicate that the rates of ESBLs are high in urine E. coli and K. pneumoniae isolates from Tehran hospitals. Also this study indicates that the urine isolates from male patients are significantly more resistant than the female isolates.