Microbiological and antimicrobial evaluation of drinking water in houses of the Brazilian Amazon

Limited access to safe water and basic sanitation contributes to morbidity and mortality caused by waterborne diseases, and reinforces social inequalities. The aim of this study was to evaluate the microbiological quality of water consumed by residents of floating houses and the antimicrobial susceptibility profile of the isolates in the low and increasing flow regime in the Amazon River basin. The samples consisted of drinking water from floating domestic units located on the edges of cities in the Amazon region, Amazonas state, Brazil. Sampling occurred during the low (LWL) and raising river-water level (RWL) periods. Water samples were analyzed using the filtering membrane method. The antimicrobial susceptibility test was performed using the disk-diffusion method. The source of water for consumption was predominantly tubular/artesian wells (75.0% LWL; 72.7% RWL); the main storage form was in PET (polyethylene terephthalate) bottles or buckets (90.9%) and the majority of the residents (63.6%) did not treat the water before consumption. Most water samples were contaminated with Escherichia coli during both the LWL (86.3%) and RWL periods (82.5%). Enterococcus spp., Vibrio spp. and Salmonella spp. were identified in association with water contamination by E. coli. Salmonella spp. exhibited the highest resistance rate among the bacteria subjected to antimicrobial susceptibility testing, especially during the LWL period; 100% showed resistance to ampicillin and cefazolin, 68% were resistant to tobramycin and 64% to gentamicin. Therefore, raising public awareness about the consumption of safe water, through dissemination of proper water storage and disinfection procedures could help minimize contamination and reduce waterborne diseases.