The emergence of multi-drug resistant strains of Escherichia coli complicates the treatment of infections. The detection of ESBL genes in bacteria and their antimicrobial resistance patterns can provide information about their epidemiology and transmission. The study aimed to detect ESBL genes that encode; CTX-M, TEM and SHV in E. coli isolatesin our locality.


Clinical E. coli isolates were obtained from public and private clinics within Calabar metropolis. Biochemical method was used to re-identify the isolates. Antibiotics susceptibility testing was done using Kirby-Bauer disc diffusion method. Phenotypic detection of ESBL in isolates was done by double disc synergy test (DDST). The ESBL genes were detected using conventional PCR method.


The ESBL phenotypic positive isolates was (56.6 %). The most prevalent gene in the study was CTX-M gene. Antibiotic susceptibility of E. coli isolates to commonly used antibiotics was low. Isolates were most susceptible to quinolones (54.7 %) and fluoroquinolones (34.0 %). The ESBL producing isolates were more susceptible to quinolones but less susceptible to the third generation cephalosporins. There was significant association between gene expression by isolates and antibiotic resistance (P≤0.05). Isolates with the SHV and TEM genes showed 100 % resistance to some tested antibiotics. Isolates with CTX-M genes were also highly resistant.


The SHV, CTX-M and TEM genes were detected in Escherichia coli isolates in our locality. These may have resulted in the high resistance of isolates to commonly used antibiotics which may pose challenges to patient’s management.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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