scholarly journals Microbial source tracking markers for detection of fecal contamination in environmental waters: relationships between pathogens and human health outcomes

2014 ◽  
Vol 38 (1) ◽  
pp. 1-40 ◽  
Author(s):  
Valerie J. Harwood ◽  
Christopher Staley ◽  
Brian D. Badgley ◽  
Kim Borges ◽  
Asja Korajkic
Keyword(s):  
Health Outcomes ◽  
Human Health ◽  
Fecal Contamination ◽  
Microbial Source Tracking ◽  
Source Tracking ◽  
Environmental Waters

An optimized enumeration method for sorbitol-fermenting Bifidobacteria in water samples

2005 ◽  
Vol 51 (5) ◽  
pp. 413-422 ◽  
Author(s):  
Sharon C Long ◽  
Catalina Arango P. ◽  
Jeanine D Plummer
Keyword(s):  
Membrane Filtration ◽  
Fecal Contamination ◽  
Domestic Wastewater ◽  
Microbial Source Tracking ◽  
Quantitative Information ◽  
Source Tracking ◽  
Human Consumption ◽  
Bromocresol Purple ◽  
Environmental Waters ◽  
Biochemical Tests

With increased focus on watershed protection under the Surface Water Treatment Rule, indicators that discriminate among sources of microbial inputs (microbial source tracking) are needed to supplement the quantitative information provided by total and fecal coliform measurements for drinking water monitoring. Bifidobacteria are found in the digestive tract and feces of humans and other animals, and also in sewage. Sorbitol is a food additive used exclusively in food intended for human consumption. Therefore, the presence of sorbitol-fermenting Bifidobacteria in environmental waters can be indicative of sources of human fecal contamination. A series of media were evaluated using ATCC cultures of B. breve and B. adolescentis, feces from different animals, and domestic wastewater samples. The media evaluated were Human Bifid Sorbitol agar (HBSA), modified Human Bifid Sorbitol agar, Beerens Medium, modified Beerens Medium, Reinforced Clostridial agar, BIM-25 Medium, and modified BIM-25 Medium. Variables such as sample preservation, incubation time, different pH indicators, plating technique, and discontinuous exposure to sorbitol were also evaluated. A series of biochemical tests were used to confirm positive colonies enumerated on the various media. Membrane filtration and enumeration of sodium sulfite preserved samples on HBSA containing bromocresol purple using loose lidded plates for 48 h provided the best recoveries for presumptive positive colonies. A number of sorbitol-fermenters that were not Bifidobacteria were able to grow on all media tested, resulting in false-positives. Therefore, plating on HBSA should be followed by a confirmation step when monitoring for sorbitol-fermenting Bifidobacteria in environmental waters. A year-long sampling survey of a managed reservoir in Massachusetts provided field validation of the proposed methodology for sorbitol-fermenting Bifidobacteria as a human-related source tracking indicator tool.Key words: sorbitol-fermenting Bifidobacteria, microbial source tracking, watershed management, fecal contamination.

Multi-Year Microbial Source Tracking Study Characterizing Fecal Contamination in an Urban Watershed

2017 ◽  
Vol 89 (2) ◽  
pp. 127-143 ◽  
Author(s):  
Rebecca N. Bushon ◽  
Amie M.G. Brady ◽  
Eric D. Christensen ◽  
Erin A. Stelzer
Keyword(s):  
Fecal Contamination ◽  
Microbial Source Tracking ◽  
Source Tracking ◽  
Urban Watershed

scholarly journals Performance of Two Quantitative PCR Methods for Microbial Source Tracking of Human Sewage and Implications for Microbial Risk Assessment in Recreational Waters

2012 ◽  
Vol 78 (20) ◽  
pp. 7317-7326 ◽  
Author(s):  
Christopher Staley ◽  
Katrina V. Gordon ◽  
Mary E. Schoen ◽  
Valerie J. Harwood
Keyword(s):  
Risk Assessment ◽  
Quantitative Pcr ◽  
Microbial Source Tracking ◽  
Human Polyomavirus ◽  
Source Tracking ◽  
Specific Marker ◽  
Environmental Waters ◽  
Potential Health ◽  
Microbial Risk Assessment ◽  
Microbial Risk

ABSTRACTBefore new, rapid quantitative PCR (qPCR) methods for assessment of recreational water quality and microbial source tracking (MST) can be useful in a regulatory context, an understanding of the ability of the method to detect a DNA target (marker) when the contaminant source has been diluted in environmental waters is needed. This study determined the limits of detection and quantification of the human-associatedBacteroidessp. (HF183) and human polyomavirus (HPyV) qPCR methods for sewage diluted in buffer and in five ambient, Florida water types (estuarine, marine, tannic, lake, and river). HF183 was quantifiable in sewage diluted up to 10−6in 500-ml ambient-water samples, but HPyVs were not quantifiable in dilutions of >10−4. Specificity, which was assessed using fecal composites from dogs, birds, and cattle, was 100% for HPyVs and 81% for HF183. Quantitative microbial risk assessment (QMRA) estimated the possible norovirus levels in sewage and the human health risk at various sewage dilutions. When juxtaposed with the MST marker detection limits, the QMRA analysis revealed that HF183 was detectable when the modeled risk of gastrointestinal (GI) illness was at or below the benchmark of 10 illnesses per 1,000 exposures, but the HPyV method was generally not sensitive enough to detect potential health risks at the 0.01 threshold for frequency of illness. The tradeoff between sensitivity and specificity in the MST methods indicates that HF183 data should be interpreted judiciously, preferably in conjunction with a more host-specific marker, and that better methods of concentrating HPyVs from environmental waters are needed if this method is to be useful in a watershed management or monitoring context.

scholarly journals Evaluation of Two Library-Independent Microbial Source Tracking Methods To Identify Sources of Fecal Contamination in French Estuaries

2007 ◽  
Vol 73 (15) ◽  
pp. 4857-4866 ◽  
Author(s):  
Michèle Gourmelon ◽  
Marie Paule Caprais ◽  
Raphaël Ségura ◽  
Cécile Le Mennec ◽  
Solen Lozach ◽  
...  
Keyword(s):  
Water Samples ◽  
Fecal Contamination ◽  
Microbial Source Tracking ◽  
Source Tracking ◽  
Rrna Gene ◽  
Specific Marker ◽  
Gene Markers ◽  
High Level ◽  
Bird Feces

ABSTRACT In order to identify the origin of the fecal contamination observed in French estuaries, two library-independent microbial source tracking (MST) methods were selected: (i) Bacteroidales host-specific 16S rRNA gene markers and (ii) F-specific RNA bacteriophage genotyping. The specificity of the Bacteroidales markers was evaluated on human and animal (bovine, pig, sheep, and bird) feces. Two human-specific markers (HF183 and HF134), one ruminant-specific marker (CF193′), and one pig-specific marker (PF163) showed a high level of specificity (>90%). However, the data suggest that the proposed ruminant-specific CF128 marker would be better described as an animal marker, as it was observed in all bovine and sheep feces and 96% of pig feces. F RNA bacteriophages were detected in only 21% of individual fecal samples tested, in 60% of pig slurries, but in all sewage samples. Most detected F RNA bacteriophages were from genotypes II and III in sewage samples and from genotypes I and IV in bovine, pig, and bird feces and from pig slurries. Both MST methods were applied to 28 water samples collected from three watersheds at different times. Classification of water samples as subject to human, animal, or mixed fecal contamination was more frequent when using Bacteroidales markers (82.1% of water samples) than by bacteriophage genotyping (50%). The ability to classify a water sample increased with increasing Escherichia coli or enterococcus concentration. For the samples that could be classified by bacteriophage genotyping, 78% agreed with the classification obtained from Bacteroidales markers.

scholarly journals Microbial Source-Tracking Reveals Origins of Fecal Contamination in a Recovering Watershed

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2162 ◽  
Author(s):  
Hyatt Green ◽  
Daniel Weller ◽  
Stephanie Johnson ◽  
Edward Michalenko
Keyword(s):  
Urban Areas ◽  
Bacterial Contamination ◽  
Fecal Contamination ◽  
Microbial Source Tracking ◽  
Mitigation Strategies ◽  
Source Tracking ◽  
Chemical Parameters ◽  
Fecal Indicator ◽  
Combined Sewer ◽  
Rain Events

Fecal contamination of waterbodies due to poorly managed human and animal waste is a pervasive problem that can be particularly costly to address, especially if mitigation strategies are ineffective at sufficiently reducing the level of contamination. Identifying the most worrisome sources of contamination is particularly difficult in periurban streams with multiple land uses and requires the distinction of municipal, agricultural, domestic pet, and natural (i.e., wildlife) wastes. Microbial source-tracking (MST) methods that target host-specific members of the bacterial order Bacteroidales and others have been used worldwide to identify the origins of fecal contamination. We conducted a dry-weather study of Onondaga Creek, NY, where reducing fecal contamination has been approached mainly by mitigating combined sewer overflow events (CSOs). Over three sampling dates, we measured in-stream concentrations of fecal indicator bacteria; MST markers targeting human, ruminant, and canine sources; and various physical–chemical parameters to identify contaminants not attributable to CSOs or stormwater runoff. We observed that despite significant ruminant inputs upstream, these contaminants eventually decayed and/or were diluted out and that high levels of urban bacterial contamination are most likely due to failing infrastructure and/or illicit discharges independent of rain events. Similar dynamics may control other streams that transition from agricultural to urban areas with failing infrastructure.

scholarly journals Use of Bacteroidales Microbial Source Tracking To Monitor Fecal Contamination in Fresh Produce Production

2013 ◽  
Vol 80 (2) ◽  
pp. 612-617 ◽  
Author(s):  
Kruti Ravaliya ◽  
Jennifer Gentry-Shields ◽  
Santos Garcia ◽  
Norma Heredia ◽  
Anna Fabiszewski de Aceituno ◽  
...  
Keyword(s):  
Fresh Produce ◽  
Fecal Contamination ◽  
Microbial Source Tracking ◽  
Source Tracking ◽  
Rrna Gene ◽  
Specific Marker ◽  
Production Environment ◽  
Content Type ◽  
Food Borne

ABSTRACTIn recent decades, fresh and minimally processed produce items have been associated with an increasing proportion of food-borne illnesses. Most pathogens associated with fresh produce are enteric (fecal) in origin, and contamination can occur anywhere along the farm-to-fork chain. Microbial source tracking (MST) is a tool developed in the environmental microbiology field to identify and quantify the dominant source(s) of fecal contamination. This study investigated the utility of an MST method based onBacteroidales16S rRNA gene sequences as a means of identifying potential fecal contamination, and its source, in the fresh produce production environment. The method was applied to rinses of fresh produce, source and irrigation waters, and harvester hand rinses collected over the course of 1 year from nine farms (growing tomatoes, jalapeño peppers, and cantaloupe) in Northern Mexico. Of 174 samples, 39% were positive for a universalBacteroidalesmarker (AllBac), including 66% of samples from cantaloupe farms (3.6 log10genome equivalence copies [GEC]/100 ml), 31% of samples from tomato farms (1.7 log10GEC/100 ml), and 18% of samples from jalapeño farms (1.5 log10GEC/100 ml). Of 68 AllBac-positive samples, 46% were positive for one of three human-specific markers, and none were positive for a bovine-specific marker. There was no statistically significant correlation betweenBacteroidalesand genericEscherichia coliacross all samples. This study provides evidence thatBacteroidalesmarkers may serve as alternative indicators for fecal contamination in fresh produce production, allowing for determination of both general contamination and that derived from the human host.

Multi-tiered approach utilizing microbial source tracking and human associated-IMS/ATP for surveillance of human fecal contamination in Baja California, Mexico

2018 ◽  
Vol 640-641 ◽  
pp. 475-484 ◽  
Author(s):  
Amity G. Zimmer-Faust ◽  
Vanessa Thulsiraj ◽  
Christine M. Lee ◽  
Victoria Whitener ◽  
Megan Rugh ◽  
...  
Keyword(s):  
Baja California ◽  
Fecal Contamination ◽  
Microbial Source Tracking ◽  
Source Tracking ◽  
Tiered Approach
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