Virulence Genes in Gram-negative Enteric Pathogens Isolated from Surface Water Sources in Adamawa North Senatorial Zone, Nigeria

Abstract

Groundwater sources such as rivers and wells remain the major water supply sources for homes in developing countries' rural areas. They are subject to anthropogenic activities such as domestic, agricultural, and industrial waste disposal. This could pose huge health risks. Rivers and wells in Adamawa North Senatorial Zone of Nigeria were screened bacteriologically to assess their quality. Samples were screened by the membrane filtration method for enteric pathogens and isolates identified by standard bacteriological and molecular methods after which they were screened for the presence of some essential virulence determinants. Escherichia coli was the most commonly isolated being recovered from 34.4% and 14.8% respectively of the river and well water samples. Others were Vibrio cholerae, Vibrio parahemolyticus, Salmonella enterica, and Shigella dysenteriae. Shigella dysenteriae, Vibrio cholerae, and Vibrio parahaemolyticus were not recovered from the well water samples. Virulence genes detected in E. coli were stx1, 13(48.2%), stx2, 22(81.5%), eaeA, 21(77.8%), and hlyA, 15(55.6%). The gene for cholera toxin, ctxAB was detected in only 2(28.6%) of the V. cholerae isolates. In comparison, hemolysin gene hlyA was detected in both V. cholerae (14.3%), V. parahaemolyticus (16.7%), S. enterica (40.0%), and the only isolate of S. dysenteriae. Detecting enteric pathogens with some putative virulence genes indicated a health risk to consumers. Intensive health education, good sanitary habits, and point-of-use water disinfection are advocated for consumers.