Supplementary Material for: Characterization of Integrons and Sulfonamide Resistance Genes among Bacteria from Drinking Water Distribution Systems in Southwestern Nigeria

<b><i>Background:</i></b> The emergence of antibiotic resistance among pathogenic bacteria in clinical and environmental settings is a global problem. Many antibiotic resistance genes are located on mobile genetic elements such as plasmids and integrons, enabling their transfer among a variety of bacterial species. Water distribution systems may be reservoirs for the spread of antibiotic resistance. <b><i>Materials and Methods:</i></b> Bacteria isolated from raw, treated, and municipal tap water samples from selected water distribution systems in south-western Nigeria were investigated using the point inoculation method with seeded antibiotics, PCR amplification, and sequencing for the determination of bacterial resistance profiles and class 1/2 integrase genes and gene cassettes, respectively. <b><i>Results:</i></b><i>sul1,</i><i>sul2,</i> and <i>sul3</i> were detected in 21.6, 27.8, and 0% of the isolates, respectively (n = 162). Class 1 and class 2 integrons were detected in 21.42 and 3.6% of the isolates, respectively (n = 168). Genes encoding resistance to aminoglycosides <i>(aadA2, aadA1,</i> and <i>aadB),</i> trimethoprim <i>(dfrA15, dfr7,</i> and <i>dfrA1),</i> and sulfonamide <i>(sul1)</i> were detected among bacteria with class 1 integrons, while genes that encodes resistance to strepthothricin <i>(sat2)</i> and trimethoprim <i>(dfrA15)</i> were detected among bacteria with class 2 integrons. <b><i>Conclusions:</i></b> Bacteria from these water samples are a potential reservoir of multidrug-resistant traits including sul genes and mobile resistance elements, i.e. the integrase gene.