Humans and Hoofed Livestock Are the Main Sources of Fecal Contamination of Rivers Used for Crop Irrigation: A Microbial Source Tracking Approach

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dc.contributor.authorDiaz-Gavidia, Constanzaen
dc.contributor.authorBarria, Carlaen
dc.contributor.authorWeller, Daniel L.en
dc.contributor.authorSalgado-Caxito, Mariliaen
dc.contributor.authorEstrada, Erika M.en
dc.contributor.authorAraya, Anibalen
dc.contributor.authorVera, Leonardoen
dc.contributor.authorSmith, Woutrinaen
dc.contributor.authorKim, Minjien
dc.contributor.authorMoreno-Switt, Andrea I.en
dc.contributor.authorOlivares-Pacheco, Jorgeen
dc.contributor.authorAdell, Aiko D.en
dc.coverage.countryChileen
dc.date.accessioned2022-11-04T16:58:11Zen
dc.date.available2022-11-04T16:58:11Zen
dc.date.issued2022-06-30en
dc.description.abstractFreshwater bodies receive waste, feces, and fecal microorganisms from agricultural, urban, and natural activities. In this study, the probable sources of fecal contamination were determined. Also, antibiotic resistant bacteria (ARB) were detected in the two main rivers of central Chile. Surface water samples were collected from 12 sampling sites in the Maipo (n = 8) and Maule Rivers (n = 4) every 3 months, from August 2017 until April 2019. To determine the fecal contamination level, fecal coliforms were quantified using the most probable number (MPN) method and the source of fecal contamination was determined by Microbial Source Tracking (MST) using the Cryptosporidium and Giardia genotyping method. Separately, to determine if antimicrobial resistance bacteria (AMB) were present in the rivers, Escherichia coli and environmental bacteria were isolated, and the antibiotic susceptibility profile was determined. Fecal coliform levels in the Maule and Maipo Rivers ranged between 1 and 130 MPN/100-ml, and 2 and 30,000 MPN/100-ml, respectively. Based on the MST results using Cryptosporidium and Giardia host-specific species, human, cattle, birds, and/or dogs hosts were the probable sources of fecal contamination in both rivers, with human and cattle host-specific species being more frequently detected. Conditional tree analysis indicated that coliform levels were significantly associated with the river system (Maipo versus Maule), land use, and season. Fecal coliform levels were significantly (p < 0.006) higher at urban and agricultural sites than at sites immediately downstream of treatment centers, livestock areas, or natural areas. Three out of eight (37.5%) E. coli isolates presented a multidrug-resistance (MDR) phenotype. Similarly, 6.6% (117/1768) and 5.1% (44/863) of environmental isolates, in Maipo and Maule River showed and MDR phenotype. Efforts to reduce fecal discharge into these rivers should thus focus on agriculture and urban land uses as these areas were contributing the most and more frequently to fecal contamination into the rivers, while human and cattle fecal discharges were identified as the most likely source of this fecal contamination by the MST approach. This information can be used to design better mitigation strategies, thereby reducing the burden of waterborne diseases and AMR in Central Chile.en
dc.description.notesWe acknowledge the financial support received from the FONDECYT 11160116 and 1221536 to ADA, FONDECYT 1181167 to AM-S, and ANID Millennium Science Initiative/Millennium Initiative for Collaborative Research on Bacterial Resistance, MICROB-R, NCN17_081 to ADA, AM-S, and JO-P. Data analysis was supported by the National Institute of Environmental Health Sciences of the National Institutes of Health (NIH) under award number T32Es007271.en
dc.description.sponsorshipFONDECYT [11160116, 1221536, 1181167]; ANID Millennium Science Initiative/Millennium Initiative for Collaborative Research on Bacterial Resistance, MICROB-R [NCN17_081]; National Institute of Environmental Health Sciences of the National Institutes of Health (NIH) [T32Es007271]en
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.3389/fmicb.2022.768527en
dc.identifier.eissn1664-302Xen
dc.identifier.other768527en
dc.identifier.pmid35847115en
dc.identifier.urihttp://hdl.handle.net/10919/112383en
dc.identifier.volume13en
dc.language.isoenen
dc.publisherFrontiersen
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectmicrobial source trackingen
dc.subjectwater qualityen
dc.subjectwaterborne pathogensen
dc.subjectCryptosporidiumen
dc.subjectGiardiaen
dc.subjectfecal coliformsen
dc.subjectantimicrobial resistanceen
dc.titleHumans and Hoofed Livestock Are the Main Sources of Fecal Contamination of Rivers Used for Crop Irrigation: A Microbial Source Tracking Approachen
dc.title.serialFrontiers in Microbiologyen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

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