Observational environmental study reveals severe pathogen, toxin, and antibiotic resistance spread in floodwaters, highlighting acute public health and sanitation risks.
Key Points
Investigate physicochemical degradation, ecotoxicity, antibiotic resistance genes, and pathogenic viral contamination in urban floodwaters during an extreme precipitation event.
Conducted high-resolution spatial water sampling across 92 sites during the flood peak in Porto Alegre, Brazil.
Assessed standardized physicochemical parameters, Daphnia magna ecotoxicity assays, and culture-based microbial quantification with antibiotic susceptibility testing.
Employed qPCR and RT-PCR to identify antibiotic resistance genes (blaKPC, blaNDM) and pathogenic enteric viruses (Norovirus GI/GII, Hepatitis A and E).
Total phosphorus reached a mean of 1.07 mg/L (21 times the legal limit), ammoniacal nitrogen reached 12.74 mg/L (3.4 times the legal limit), turbidity exceeded 470 NTU, and E. coli levels exceeded recreational standards by more than an order of magnitude.
Identified multidrug-resistant bacteria, widespread carbapenemase genes (blaKPC, blaNDM), acute ecotoxicity to Daphnia magna in stagnant zones, and presence of Norovirus GI/GII and Hepatitis A and E viruses.
Sanitation failures led to the discharge of ~50,000 m³/day of raw sewage and the shutdown of five of six drinking water plants, depriving 1.23 million residents of potable water.