Antibiotic resistance of E. coli isolates from different water sources in Mbarara, Uganda

Escherichia coli is widely used as an indicator of recent faecal pollution of water. Most E. coli strains are commensals; however, isolates in water samples have been shown to carry antibiotic resistance determinants. A total of 47 E. coli were isolated from selected drinking water sources in Mbarara, Uganda. The isolates were examined for their susceptibility to seven antibiotics and the presence of nine antibiotic-resistance genes (mostly beta-lactamase genes) and class 1 integrons. Isolates showed a high resistance to ampicillin of 55.5% and a high sensitivity to azithromycin and gentamicin at 98 and 96%, respectively. PCR analysis showed the presence of extended spectrum beta-lactamase genes bla(CTX-M-32) and bla(CMY-2) in 64 and 36% of the isolates. The carbapenemase genes bla(OXA-48), bla(VIM-2), bla(NDM-1), and bla(KPC-3) were either not detected or only in a very small number of the isolates, whereas class 1 integrons were present in 68% of the isolates. This study proves, that antimicrobial resistance exists in E. coli in water used for drinking purposes in Mbarara city. There is a need for public health actors to improve surveillance of microbiological quality of drinking water to minimize health risks.