Detection of blaCTX-M, blaTEM, and blaSHV genes in clinical isolates of Escherichia coli and Klebsiella pneumoniae from Nigeria

The increasing prevalence of extended-spectrum beta-lactamases (ESBL) producing Escherichia coli and Klebsiella pneumoniae has become a major problem in the clinical setting. As a part of an antimicrobial resistance surveillance program in southeast Nigeria; this study determined the rate of ESBL genes among clinical isolates of E. coli and K. pneumoniae from major hospitals in Owerri southeast Nigeria. The microbiological culture-based method was used for the cultivation and identification of bacteria. The double-disk synergy test was used to phenotypically evaluate ESBL production while PCR confirmed the ESBL genes. A total of 433 samples were analyzed; 249 (57.5%) yielded bacteria growth comprising of consecutive 163 (65.5%) E. coli and 86 (34.5%) K. pneumoniae. The isolates were resistant to a wide range of antibiotics, with the highest rate observed in ceftazidime (90.8%) and lowest in imipenem (26.9%). There was no significant difference in the rate of resistance between E. coli and K. pneumoniae (P > 0.05). Phenotypically, ESBL was observed in 91 (36.5%) of the isolates while PCR detected three ESBL genes; blaCTX-M,blaTEM, and blaSHV. All isolates analyzed by PCR harbored at least one ESBL gene; with blaCTX-M being the most prevalent, (97.3%) followed by blaTEM (75.7%) and blaSHV (32.4%). Multidrug resistance (MDR) was observed in all isolates carrying the ESBL genes. These data, showing a high prevalence of ESBL genes will provide baseline information to the clinicians in the management of antimicrobial-resistant bacteria in the hospitals.