Surface waters in northern Tanzania harbor fecal coliform and antibiotic resistant Salmonella spp. capable of horizontal gene transfer

Some Salmonella spp. are important pathogenic bacteria that can be transmitted to people via food and water and that can cause disease characterized by mild to severe enteric and systemic illness. In developing countries, infections caused by pathogenic antibiotic resistant Salmonella spp. are a major health challenge, particularly in children. Through the use of membrane filtration and Environmental Protection Agency (EPA) 1200 methods, the presence of fecal coliforms and antibiotic resistant Salmonella spp. in surface water sources was investigated, some of which had shared access for animals and people. Out of 100 water samples, 76 were positive for fecal coliforms and 63% of the positive samples contained >100 CFU / 100 ml of water. We observed a significant positive correlation between the number of fecal coliforms and the presence of Salmonella spp. (r=0.46, n=100, P=0.01). Importantly, >26% of the samples were positive for Salmonella spp. and 88% of these samples harbored isolates resistant to ≥1 antibiotic. Moreover, we found that 26% of antibiotic resistant Salmonella spp. isolates were able to transfer their resistance traits to a recipient strain of Escherichia coli at the rate of 1-7 x 10-3 per donor cells. Microbiological contamination of water was clearly evident in open water sources from northern Tanzania, and the presence of Salmonella spp. poses an immediate risk to anyone who consumes these waters if untreated.