ASSESSMENT OF ANTIMICROBIAL RESISTANCE PLASMIDS IN ESCHERICHIA COLI ISOLATED FROM KWALKWALAWA WATER

Abstract

This study assessed the microbial quality, antibiotic resistance patterns, and plasmid profiles of bacteria isolated from Kwalkwalawa River. Biochemical characterization identified both environmental and fecal-associated bacteria, including Bacillus pumilus, Bacillus laterosporus, Serratia marcescens, Enterobacter cloacae, and Escherichia coli. The presence of E. coli indicates fecal contamination and potential health risks for communities utilizing the river. Coliform enumeration using the Most Probable Number (MPN) method revealed severe contamination at sampling point KWA (1100 MPN/100 mL) compared to KWB (75 MPN/100 mL), far exceeding WHO’s recommended limit of zero coliforms in potable water. Antibiotic susceptibility testing showed widespread resistance to beta-lactam antibiotics, with all isolates resistant to Ampicillin and Amoxicillin, whereas fluoroquinolones, including Ciprofloxacin and Ofloxacin, remained highly effective. Plasmid analysis indicated that only one E. coli isolate carried a detectable plasmid, suggesting plasmid-mediated resistance, while other isolates may possess chromosomal resistance determinants. These findings highlight significant microbial pollution and the presence of antibiotic-resistant bacteria in the river, emphasizing the need for improved water quality monitoring and public health interventions.

Keywords: Escherichia coli, antimicrobial resistance, plasmid-mediated antimicrobial resuistance, biochemical characterization.