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 blaCTX-M, 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 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.