DNA microarray-based detection of antibiotic resistance genes of human isolates of Escherichia coli in Nigeria

Molecular epidemiology of human ecovariants of Escherichia coli from different regions of Nigeria were studied using their antibiotic susceptibility patterns, plasmid profile and DNA microarray techniques. E. coli was isolated using Eosin Methylene Blue agar (EMB) and identified by conventional microbiological technique. The isolates were tested against 14 antibiotics using the disc diffusion method. Genotyping was done using DNA microarray. Overall, 42 different antibiotics resistance clusters were observed, with each isolate showing resistance to at least four or more drugs tested. Of the 60 isolates genotyped with DNA microarray, 57 were identified as having, at least, one antimicrobial resistance gene. Among the 90 antibiotic resistance genes detected, bla-CMY-2 was the most prevalent occurring in 38 (63.3%) of the isolates. Other highly prevalent genes occurring in the human isolates, include strA 28(70%) aadE 28(70%); TEM1 11(27.5%); Sul2 14(35%); andTetA 21(52.5%). The microarray genotyping corresponded with the phenotype of the strains. Presence of drug-resistance genes/plasmids in commensal strains isolated from apparently healthy individuals is of great public health importance.   Key words: DNA microarray, E. coli, Nigeria.