Detection of Extended Spectrum Beta-Lactamases Resistance Genes among Bacteria Isolated from Selected Drinking Water Distribution Channels in Southwestern Nigeria

Extended Spectrum Beta-Lactamases (ESBL) provide high level resistance to beta-lactam antibiotics among bacteria. In this study, previously described multidrug resistant bacteria from raw, treated, and municipal taps of DWDS from selected dams in southwestern Nigeria were assessed for the presence of ESBL resistance genes which include bla(TEM), bla(SHV), and bla(CTX) by PCR amplification. A total of 164 bacteria spread across treated (33), raw (66), and municipal taps (68), belonging to alpha-Proteobacteria, beta-Proteobacteria, gamma-Proteobacteria, Flavobacteriia, Bacilli, and Actinobacteria group, were selected for this study. Among these bacteria, the most commonly observed resistance was for ampicillin and amoxicillin/clavulanic acid (61 isolates). Sixty-one isolates carried at least one of the targeted ESBL genes with bla(TEM) being the most abundant (50/61) and bla(CTX) being detected least (3/61). Klebsiella was the most frequently identified genus (18.03%) to harbour ESBL gene followed by Proteus (14.75%). Moreover, combinations of two ESBL genes, bla(SHV) + bla(TEM) or bla(CTX) + bla(TEM), were observed in 11 and 1 isolate, respectively. In conclusion, classic bla(TEM) ESBL gene was present in multiple bacterial strains that were isolated from DWDS sources in Nigeria. These environments may serve as foci exchange of genetic traits in a diversity of Gram-negative bacteria.