Quantitative microbial risk assessment for waterborne pathogens in a wastewater treatment plant and its receiving surface water body

BMC Microbiology

Akebe Luther King Abia¹  Sabiha. Y. Essack¹  Daniel Gyamfi Amoako¹  Joshua Mbanga² 

[1] Antimicrobial Research Unit, College of Health Sciences, University of Kwazulu-Natal, Private Bag X54001, 4000, Durban, South Africa;Antimicrobial Research Unit, College of Health Sciences, University of Kwazulu-Natal, Private Bag X54001, 4000, Durban, South Africa;Department of Applied Biology and Biochemistry, National University of Science and Technology, P.O Box AC 939 Ascot, 00263, Bulawayo, Zimbabwe;

关键词: Quantitative microbial risk assessment;    Wastewater treatment plants;    Escherichia coli;    Enterococcus;   

DOI  :  10.1186/s12866-020-02036-7

来源: Springer

【 摘 要 】

BackgroundAccess to safe water for drinking and domestic activities remains a challenge in emerging economies like South Africa, forcing resource-limited communities to use microbiologically polluted river water for personal and household purposes, posing a public health risk. This study quantified bacterial contamination and the potential health hazards that wastewater treatment plant (WWTP) workers and communities may face after exposure to waterborne pathogenic bacteria in a WWTP and its associated surface water, respectively.ResultsEscherichia coli (Colilert®-18/ Quanti-Tray® 2000) and enterococci (Enterolert®/ Quanti-Tray® 2000) were quantified and definitively identified by real-time polymerase chain reaction targeting the uidA and tuf genes, respectively. An approximate beta-Poisson dose-response model was used to estimate the probability of infection (Pi) with pathogenic E. coli. Mean E. coli concentration ranged from 2.60E+ 02/100 mL to 4.84E+ 06/100 mL; enterococci ranged from 2.60E+ 02/100 mL to 3.19E+ 06/100 mL across all sampled sites. Of the 580 E. coli isolates obtained from this study, 89.1% were intestinal, and 7.6% were extraintestinal pathogenic E. coli. The 579 enterococci obtained were 50.4% E. faecalis (50.4%), 31.4% E. faecium, 3.5%, E. casseliflavus and 0.7% E. gallinarum. The community health risk stemming from the use of the water for recreational and domestic purposes revealed a greater health risk (Pi) from the ingestion of 1 mL of river water from upstream (range, 55.1–92.9%) than downstream (range, 26.8–65.3%) sites. The occupational risk of infection with pathogenic E. coli for workers resulting from a once-off unintentional consumption of 1 mL of water was 0% (effluent) and 23.8% (raw influent). Multiple weekly exposures of 1 mL over a year could result in a Pi of 1.2 and 100% for the effluent and influent, respectively.ConclusionOur findings reveal that there is a potentially high risk of infection for WWTP workers and communities that use river water upstream and downstream of the investigated WWTP.

【 授权许可】

CC BY