Assessment of water quality and occurrence of multidrug-resistant clinically relevant bacteria in drinking water in the twin cities of Pakistan

Water filtration plants are a main source of drinking water for local populations in almost all big cities of Pakistan but these filtration plants are ineffective in eliminating contaminants from water. This study was conducted to evaluate water quality with specific focus on physicochemical parameters and bacterial contamination including occurrence of multidrug-resistant bacteria in drinking water collected from filtration plants (N = 64) of the twin cities of Pakistan. Physicochemical parameters were analyzed following American Public Health Association standard guidelines and total coliform count was determined using membrane filtration method. Gram-negative bacteria were isolated and characterized in terms of species and antibiotic susceptibility. Elevated levels of total dissolved solids, nitrates, total coliforms, lead and copper were found in several samples. Multivariate correlation coefficient revealed significant positive correlation between nitrate levels and total coliform count in bacteriologically contaminated samples. Antibiotic resistance patterns revealed multidrug-resistant and extensively drug-resistant bacteria with high resistance against third generation cephalosporins. Our results highlight the urgent need for improved water filtration processes and regular monitoring to provide safe drinking water to the local community.