Extended Spectrum β-lactamases in Clinical Isolates of Escherichia coli and Enterobacter cloacae Collected from Nablus District - Palestine

Aim: To determine the prevalence of extended-spectrum β-lactamases (ESBLs) among clinical isolates of Escherichia coli (E. coli) and Enterobacter cloacae (E. cloacae) in Nablus district. Methodology: In this prospective study carried out at An-Najah National University, a total of 161 bacterial isolates were collected during a12-month period in Nablus district in Palestine. To detect ESBLs, the isolates were examined by combination disc method. PCR was used to detect blaCTXM, blaTEM and blaSHV genes in 32 representative ESBL-producer E. coli isolates. Results: Using combination disc method, ESBL enzymes were detected in 73 out 153 (47.7%) E. coli and in 1 out of 8 (12.5%) E. cloacae isolates. No significant association of ESBL-producer E. coli was observed with types of collected specimens, gender, hospital ward, outpatient, or medical source. Among 32 representative E. coli ESBL-positive, blaCTX-M, blaTEM and blaSHV genes were detected in 30 (93.8%), 2 (6.3%) and 1 (3.1%), respectively. Two new variants of ESBLs (PALTEM137b and PALSHV-2a') were identified. A unique E. cloacae isolate expressing inducible Short Research Article Al-Masri et al.; BMRJ, 16(3): 1-7, 2016; Article no.BMRJ.27892 2 class C B-lactamase was also detected. Conclusions: In Nablus region, high frequencies of ESBLs were found among E. coli bacteria isolated from outpatients and inpatients. blaCTX-M is the predominant gene among ESBL producers. New variants of ESBLs were found.