Antibiotic resistance and genetic diversity in water-borne Enterobacteriaceae isolates from recreational and drinking water sources

Abstract

A total of 240 water-borne bacteria including 72 Escherichia coli, 83 Enterobacter, 30 Klebsiella, 36 Salmonella and 19 Shigella spp. isolates from drinking and recreational water sources were assessed for antibiotic resistance and genetic diversity. Escherichia coli (88.89 %) and species of Enterobacter (86.75 %), Klebsiella (83.33 %) and Salmonella (100 %) were resistant to cefadroxil, while >94 % Shigella spp. were resistant to cefaclor and cefuroxime. Ofloxacin was the most effective antibiotic against isolates of all the genera. Multiple antibiotic resistance index identified dug well, pond and piped water supplies as high risk sources of enteric pathogens. Random amplified polymorphic DNA analysis and restriction fragment length polymorphism of amplified 16S rRNA gene were studied for genetic relatedness of Enterobacteriaceae isolates. Primer P1254 identified 10, 16, 4, 4 and 1 distinct random amplified polymorphic DNA group(s) of E. coli, Enterobacter, Klebsiella, Salmonella and Shigella species, respectively. Unlike random amplified polymorphic DNA, restriction fragment length polymorphism using AluI and HaeIII could not segregate isolates in different genetic profiles. 16S rRNA gene of three Enterobacter spp. strains from different sources with similar restriction fragment length polymorphism but different random amplified polymorphic DNA patterns was sequenced, and identified as Enterobacter hormaechei strains skg0061, 0062 and 0063. The sequence information has been submitted to GenBank (HQ322393-95). Biochemically similar but genetically diverse Enterobacteriaceae members from drinking and recreational water sources exhibited varying antibiotic sensitivity. Contamination of water sources with such multiple antibiotic-resistant enteric pathogens poses threat to human health.