Recreational water quality in the river Mahaweli, Sri Lanka: Enumeration and antibiotic sensitivity of Escherichia coli and sociological aspects

Abstract

Although recreational water quality affects health, in Sri Lanka, recreational water quality is hardly assessed. Faecal contamination of water poses health risks as faeces are a source of pathogens. The current study aimed to investigate Escherichia coli in recreational water by enumerating and assessing antibiotic sensitivity, and to conduct a sociological survey. Water samples (n = 72) were collected from six bathing locations along the river Mahaweli during rainy and dry periods, and subjected to membrane filtration. Typical blue colonies on m-FC agar were enumerated. An antibiotic sensitivity test was performed on E. coli isolates using seven antibiotics commonly used in Sri Lanka. Escherichia coli counts in 95.0% of water samples exceeded the permissible limit (235 CFU/100 mL). Mean E. coli counts were significantly higher (p < 0.05) during the rainy period compared to the dry period. In both periods, mean counts were significantly higher (p < 0.05) in more populated locations than less populated locations. Antibiotic resistant E. coli were present in varying degrees in all locations. Isolates were resistant to ciprofloxacin (56.5%), cefotaxime (4.8%), amoxicillin-clavulanate (4.2%), amikacin (3.0%), and ticarcillin-clavulanate (0.6%). None were resistant to imipenem or meropenem. The percentages of isolates resistant to amikacin, amoxicillin-clavulanate, and ciprofloxacin were significantly higher in less populated locations compared to more populated locations (p < 0.05), while the percentage for cefotaxime was higher in more populated locations. According to the sociological survey (n = 60), inadequate sewage facilities and urban runoff are likely reasons of pollution. Elevated E. coli counts and the presence of antibiotic-resistant E. coli render the water unsuitable for recreational purposes.