Occurrence and molecular detection of antibiotic-resistant genes in Escherichia coli isolated from drinking water in selected locations in southwestern Nigeria

Abstract

The quality of water available for households’ use was investigated in some selected locations in Nigeria. A total of 180 water samples were analyzed. The antimicrobial susceptibility testing of the Escherichia coli from the water samples was determined using standard microbiological protocols and detection of extended-spectrum β-lactamase (ESBL) resistance genes. Microbiological mean total coliform count values obtained in both stored and source water in sampling locations were high ranging from 3.10 ± 1.46 to 156.80 ± 42.9 cfu/100 ml for stored water and from 0.50 ± 0.31 to 90.60 ± 38.05 cfu/100 ml for source water. Also, the majority of the source waters were devoid of fecal coliform, whereas the stored water had mean count values between 0.80 ± 0.70 and 64.30 ± 14.15 cfu/100 ml. Twenty-five E. coli isolates obtained from the water samples were resistant to most antibacterial used. However, four of the E. coli isolates were sensitive to cefotaxime. Polymerase chain reaction (PCR) revealed that 11 out of 25 E. coli isolates (44%) screened for ESBL resistance genes had TEM genes, while four of the isolates (16%) had SHV genes. This study concluded that drinking water could be a source of exposure to antibiotic-resistant E. coli, which may pose a threat to human populations and their health in the study area.