Distribution of antibiotic-resistance genes in ultraviolet-treated water samples

Abstract

Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARG) are a global health problem. Their detection in drinking water samples speaks volumes because water is an essential prerequisite for a healthy life. This study aimed to evaluate the ARG distribution in ultraviolet (UV) treated water samples. One litre each of the thirty well water and borehole water samples was obtained from different dormitories at Ekiti State University in Ekiti State. Each water sample was treated with ultraviolet at 254 nm for 30 min. Bacterial detection and isolation were performed on UV-treated water samples using the standard pour plate technique, and the identification of isolates was performed using standard biochemical methods. The isolates were tested for antibiotic sensitivity according to the Institute of Clinical and Laboratory Standards' procedures. Five ARBs exhibiting resistance to multiple antibiotics were selected and subsequently detected at the molecular level of ARG including tetA, ctx-M and sul1 by PCR technique. Twenty different bacteria belonging to seven species were identified: Escherichia coli (25%), Klebsiella aerogenes (5%), Enterobacter aerogenes (10%), Staphylococcus aureus (25%), Proteus spp. (5%), Bacillus lichenifomis (10%) and Bacillus cereus (20%). A remarkable resistance profile was observed among the bacteria and tetA gene was present in Staphylococcus aureus and E. coli. Only Enterobacter aerogenes was positive for sul1 genes and none of the bacterial isolates was positive for ctx-M. The study showed that ARG persisted despite UV treatment, indicating that water treatment did not completely remove ARG. Hence the spread of ARG in the environment.