Prevalence of CTX-3 family gene among clinical isolates of Escherichia coli and Klebsiella pneumoniae from patients hospitalized in Sina Hospital, Tabriz

Emerging resistance to beta-lactam antibiotics among gram negative bacteria limits their usage. This study was done to determine the frequency of ESBLs producers and presence of CTX-M3 family gene (including CTX-M 3, 15, 22 subfamily) in Escherichia coli and Klebsiella pneumoniae isolated from different clinical specimens in Sina Hospital, Tabriz

71 isolates of E. coli and 63 K. pneumoniae were isolated from different clinical specimens sent to Division of Microbiology, Sina Hospital, Tabriz, Iran. Bacteria were identified by conventional phenotypic methods. ESBL production in E. coli and K. pneumoniae was first detected with combined disc method using Mueller-Hinton agar and later presence of CTX-M3 family gene was detected by PCR technique.

In this study, 41 (57.74%) E.coli and 45 (71.42%) K. pneumoniae isolates were observed as ESBL producers. Among them, 30 (73.17%) E. coli and 26 (57.77%) K.pneumoniae were found carrying CTX-M3 gene. Among various antibiotics used for ESBL detection, highest resistance towards cefpodoxime (92%) was observed in E.coli, while in K.pneumoniae 90% isolates show resistance towards cefpodoxime and azterornam.

Our study revealed that there is a high frequency of ESBLs producing isolates of E. coli and K. pneumoniae in our hospital set up. The problem elucidates the importance of designing more controlled surveillance of antibiotic resistance and need for large-scale epidemiologic studies to identify outcomes of the ESBL-production in gram negative bacilli.