Quantitative and qualitative assessments of microbial contamination in some bottled and tap water, and their drug resistant pattern

Abstract

The present work focussed on the concerns of the existence of coliform, faecal coliform, and other pathogens in both tap water and commercially available bottled water, along with the drug resistant pattern of the isolates. The physico-chemical features of the bottled water samples were satisfactory, but most of the tap water exceeded the marginal limit. A total of 21 samples (10 of tap water and 11 of bottled water) were collected and processed for microbiological analysis. All the samples were found to be contaminated with total viable bacteria up to 108 CFU/mL. Among the 21 samples, seven samples were found to be contaminated with E. coli up to 106 CFU/mL, and six samples had Klebsiella spp. up to 102 CFU/mL. Faecal contamination was totally absent in all bottled water, but present in four tap water samples. Fungi was found in six samples within the range of 102 to 103 CFU/mL. Surprisingly, Staphylococcus spp. were observed in all bottled water. Vibrio spp. were detected in three samples. An elevated number of faecal coliforms, Klebsiella spp., Salmonella spp., Shigella spp., Vibrio spp., and Pseudomonas spp. were estimated among the tap water samples up to 105 CFU/mL. The water samples, especially tap water, collected from the different areas were microbiologically unsafe, as few pathogenic microorganisms were found in several samples. This indicated as public health threat. Most of the isolates from both tap and bottled water samples were found to be resistant against more than one antibiotic tested, which is extremely alarming for the consumers. Very few antibiotics were found to be effective against the bacterial isolates.