Occurrence of waterborne pathogens and antibiotic resistance in water supply systems in a small town in Mozambique

Background . Microbiological quality of drinking water supplied in Moamba, a small town in southern Mozambique, was assessed by collecting and analyzing 91 water sample from 5 sampling sites: raw or inlet water, treated water and 3 household taps along the water distribution system. The presence of Escherichia coli as indicator fecal contamination, three bacterial pathogens, Vibrio cholerae , Salmonella and Campylobacter spp., and Cefotaximee resistant E. coli as antibiotic resistance determinant, was assessed. Results . The results showed fecal contamination in all types of water samples: E. coli was found in 100% of inlet water samples, in 21% of treated water samples, and in 22% of tap water samples. No Salmonella spp. was detected during the study. The presence of V. cholerae was detected in 42% of all water samples tested: 100% of inlet water samples, in 16% of treated water samples, and in 23% household tap water samples. All V. cholerae confirmed isolates where genotyped by PCR as non-O1/non-O139; however, 9 isolates showed the presence of the genes encoding for cholera toxin. The presence of Campylobacter spp. was detected in 36% of the water samples tested: in 95% of inlet water samples, in 10% of treated water samples and in 23% household tap water samples. Cefotaxime resistant E. coli was detected in 63% of inlet water, 16% of treated water, and in 9% of tap water samples, these isolates were also resistant to multiple other antibiotics: ampicillin, streptomycin, tetracycline chloramphenicol. All 70 V. cholerae non-O1/non-O139 confirmed isolated were resistant to ampicillin, 51% to streptomycin, 13% to gentamycin, and 1 isolate was resistant to tetracycline; 13% showed a multi-drug resistant profile, being resistant to at least three antibiotics. Conclusion . The presence of fecal contamination and pathogens in the water treatment system and household taps in Moamba indicates a health risk for the population. This burden increases by the presence of bacterial pathogens showing multidrug resistance.