scholarly journals Enterococci in the Environment

2012 ◽  
Vol 76 (4) ◽  
pp. 685-706 ◽  
Author(s):  
Muruleedhara N. Byappanahalli ◽  
Meredith B. Nevers ◽  
Asja Korajkic ◽  
Zachery R. Staley ◽  
Valerie J. Harwood

SUMMARYEnterococci are common, commensal members of gut communities in mammals and birds, yet they are also opportunistic pathogens that cause millions of human and animal infections annually. Because they are shed in human and animal feces, are readily culturable, and predict human health risks from exposure to polluted recreational waters, they are used as surrogates for waterborne pathogens and as fecal indicator bacteria (FIB) in research and in water quality testing throughout the world. Evidence from several decades of research demonstrates, however, that enterococci may be present in high densities in the absence of obvious fecal sources and that environmental reservoirs of these FIB are important sources and sinks, with the potential to impact water quality. This review focuses on the distribution and microbial ecology of enterococci in environmental (secondary) habitats, including the effect of environmental stressors; an outline of their known and apparent sources, sinks, and fluxes; and an overview of the use of enterococci as FIB. Finally, the significance of emerging methodologies, such as microbial source tracking (MST) and empirical predictive models, as tools in water quality monitoring is addressed. The mounting evidence for widespread extraenteric sources and reservoirs of enterococci demonstrates the versatility of the genusEnterococcusand argues for the necessity of a better understanding of their ecology in natural environments, as well as their roles as opportunistic pathogens and indicators of human pathogens.

2014 ◽  
Vol 81 (1) ◽  
pp. 196-202 ◽  
Author(s):  
Jennifer Weidhaas ◽  
Sirisha Mantha ◽  
Elliott Hair ◽  
Bina Nayak ◽  
Valerie J. Harwood

ABSTRACTWater quality monitoring techniques that target microorganisms in the orderBacteroidalesare potential alternatives to conventional methods for detection of fecal indicator bacteria.Bacteroidalesand members of the genusBacteroideshave been the focus of microbial source tracking (MST) investigations for discriminating sources of fecal pollution (e.g., human or cattle feces) in environmental waters. For accurate source apportionment to occur, one needs to understand both the abundance ofBacteroidesin host feces and the survival of these host-associated microbial markers after deposition in the environment. Studies were undertaken to evaluate the abundance, persistence, and potential for growth ofBacteroidalesoriginating from poultry litter under oxic and anoxic environmental conditions.Bacteroidalesabundance, as determined by quantitative PCR (qPCR) with GenBac primers and probe, increased 2 to 5 log gene copies ml−1and 2 log gene copies g litter−1under most conditions during incubation of poultry litter in a variety of laboratory microcosm and field mesocosm studies. DNA sequencing of theBacteroidalesorganisms in the litter identified taxa with sequences corresponding exactly to the GenBac primer and probe sequences and that were closely related toBacteroides uniformis,B. ovatus, andB. vulgatus. These results suggest that MST studies using qPCR methods targetingBacteroidalesin watersheds that are affected by poultry litter should be interpreted cautiously. Growth ofBacteroidalesoriginating from poultry litter in environmental waters may occur whileBacteroidalesgrowth from other fecal sources declines, thus confounding the interpretation of MST results.


2013 ◽  
Vol 80 (5) ◽  
pp. 1588-1594 ◽  
Author(s):  
Orin C. Shanks ◽  
Catherine A. Kelty ◽  
Lindsay Peed ◽  
Mano Sivaganesan ◽  
Thomas Mooney ◽  
...  

ABSTRACTCalves make up about 16% of the current bovine population in the United States and can excrete high levels of human pathogens in their feces. We describe the density and distribution of genetic markers from 9 PCR- and real-time quantitative PCR-based assays, including CF128, CF193, CowM2, CowM3, GenBac3, Entero1, EC23S857, CampF2, and ttr-6, commonly used to help assess ambient surface water quality. Each assay was tested against a collection of 381 individual bovine fecal samples representing 31 mother and calf pairings collected over a 10-month time period from time of birth through weaning. Genetic markers reported to be associated with ruminant and/or bovine fecal pollution were virtually undetected in calves for up to 115 days from birth, suggesting that physiological changes in calf ruminant function impact host-associated genetic marker shedding. In addition, general fecal indicator markers forBacteroidales,Escherichia coli, andEnterococcusspp. exhibited three separate trends across time, indicating that these bacteria respond differently to age-related physiological and dietary changes during calf development. The results of this study suggest that currently available PCR-based water quality indicator technologies can under- or overestimate fecal pollution originating from calves and identify a need for novel calf-associated source identification methods.


2012 ◽  
Vol 78 (18) ◽  
pp. 6423-6432 ◽  
Author(s):  
Shannon McQuaig ◽  
John Griffith ◽  
Valerie J. Harwood

ABSTRACTWater quality was assessed at two marine beaches in California by measuring the concentrations of culturable fecal indicator bacteria (FIB) and by library-independent microbial source tracking (MST) methods targeting markers of human-associated microbes (human polyomavirus [HPyV] PCR and quantitative PCR,Methanobrevibacter smithiiPCR, andBacteroidessp. strain HF183 PCR) and a human pathogen (adenovirus by nested PCR). FIB levels periodically exceeded regulatory thresholds at Doheny and Avalon Beaches for enterococci (28.5% and 31.7% of samples, respectively) and fecal coliforms (20% and 5.8%, respectively). Adenoviruses were detected at four of five sites at Doheny Beach and were correlated with detection of HPyVs and humanBacteroidesHF183; however, adenoviruses were not detected at Avalon Beach. The most frequently detected human source marker at both beaches wasBacteroidesHF183, which was detected in 27% of samples. Correlations between FIBs and human markers were much more frequent at Doheny Beach than at Avalon Beach; e.g., adenovirus was correlated with HPyVs and HF183. Human sewage markers and adenoviruses were routinely detected in samples meeting FIB regulatory standards. The toolbox approach of FIB measurement coupled with analysis of several MST markers targeting human pathogens used here demonstrated that human sewage is at least partly responsible for the degradation of water quality, particularly at Doheny Beach, and resulted in a more definitive assessment of recreational water quality and human health risk than reliance on FIB concentrations alone could have provided.


2012 ◽  
Vol 78 (12) ◽  
pp. 4420-4433 ◽  
Author(s):  
Brian D. Sauders ◽  
Jon Overdevest ◽  
Esther Fortes ◽  
Katy Windham ◽  
Ynte Schukken ◽  
...  

ABSTRACTA total of 442Listeriaisolates, including 234Listeria seeligeri, 80L. monocytogenes, 74L. welshimeri, 50L. innocua, and 4L. marthiiisolates, were obtained from 1,805 soil, water, and other environmental samples collected over 2 years from four urban areas and four areas representing natural environments.Listeriaspp. showed similar prevalences in samples from natural (23.4%) and urban (22.3%) environments. WhileL. seeligeriandL. welshimeriwere significantly associated with natural environments (P≤ 0.0001),L. innocuaandL. monocytogeneswere significantly associated with urban environments (P≤ 0.0001). Sequencing ofsigBfor all isolates revealed 67 allelic types with a higher level of allelic diversity among isolates from urban environments. SomeListeriaspp. andsigBallelic types showed significant associations with specific urban and natural areas. Nearest-neighbor analyses also showed that certainListeriaspp. andsigBallelic types were spatially clustered within both natural and urban environments, and there was evidence that these species and allelic types persisted over time in specific areas. Our data show that members of the genusListerianot only are common in urban and natural environments but also show species- and subtype-specific associations with different environments and areas. This indicates thatListeriaspecies and subtypes within these species may show distinct ecological preferences, which suggests (i) that molecular source-tracking approaches can be developed forListeriaand (ii) that detection of someListeriaspecies may not be a good indicator forL. monocytogenes.


2021 ◽  
Author(s):  
Megan Devane ◽  
Brent Gilpin ◽  
Jennifer Webster-Brown ◽  
Louise Weaver ◽  
Pierre Dupont ◽  
...  

<p>The intensification of dairy farming on the agricultural landscape in New Zealand has raised concerns about pollution sources from dairy faecal runoff into waterways. The transport of faecal pollution from farms into waterways is facilitated by overland flow, which can result from rain and flood events, poorly designed irrigation practices and the washing down of milking sheds.</p><p>An important step for mitigation of pollution is the identification of the source(s) of faecal contamination. When elevated levels of faecal indicator bacteria (FIB) such as <em>Escherichia coli </em>are identified in a waterway, faecal source tracking (FST) tools such as microbial source tracking (MST) using quantitative polymerase chain reaction (qPCR), and faecal steroids (for example, cholesterol) provide information about the sources of faecal contamination. The understanding of the fate (degradation/persistence) and transport of these FST markers in the environment is recognised as an important requirement for the interpretation of water quality monitoring in aquatic environments.</p><p>This study investigated the effects of faecal decomposition on bovine faecal indicators (<em>E. coli </em>and FST markers: bovine-associated qPCR markers and ten faecal steroids) by monitoring the effect of flood and rainfall events on simulated cowpats over a five and a half month period under field conditions. Two separate spring/summer trials were conducted to evaluate: Trial 1) the mobilisation under simulated flood conditions of the faecal indicators from irrigated versus non-irrigated cowpats, Trial 2) the mobilisation of faecal indicators from non-irrigated cowpat flood runoff versus runoff after simulated rainfall onto non-irrigated cowpats.</p><p>The microbial community changes within the decomposing cowpat (as illustrated by amplicon-based metagenomic analysis) were expected to impact on the survival/persistence of the bacterial targets of the MST markers, and also alter the ratio between faecal sterols and their biodegradation products, the stanols. It was hypothesised, therefore, that there would be:</p><ul><li>Changes over time in the concentration of<em> E. coli </em>and the bovine-associated MST markers mobilised into the cowpat runoff</li> <li>Alterations in the FST ratio signature of the ten measured faecal steroids, resulting in a change from a bovine faecal steroid signature in fresh cowpat runoff to other animal faecal signatures in the runoff from decomposing cowpats</li> <li>A difference in the mobilisation decline rates of all FST and microbial markers within a treatment regime and between treatments.</li> </ul><p>Linear regression analysis was undertaken to establish mobilisation decline rates for each of the analytes in the mobilisable phase from the cowpat runoff treatments, with calculation of the time taken in days for reduction in 90% of the concentration (T<sub>90</sub>), and statistical comparison of the regression coefficients (slopes) of all analytes. The results will include a discussion of the impacts of the study’s observations on the interpretation of faecal indicator assessments for water quality monitoring in waterways influenced by sources of faecal contamination.</p>


2013 ◽  
Vol 80 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Adelumola Oladeinde ◽  
Thomas Bohrmann ◽  
Kelvin Wong ◽  
S. T. Purucker ◽  
Ken Bradshaw ◽  
...  

ABSTRACTUnderstanding the survival of fecal indicator bacteria (FIB) and microbial source-tracking (MST) markers is critical to developing pathogen fate and transport models. Although pathogen survival in water microcosms and manure-amended soils is well documented, little is known about their survival in intact cow pats deposited on pastures. We conducted a study to determine decay rates of fecal indicator bacteria (Escherichia coliand enterococci) and bovine-associated MST markers (CowM3, Rum-2-bac, and GenBac) in 18 freshly deposited cattle feces from three farms in northern Georgia. Samples were randomly assigned to shaded or unshaded treatment in order to determine the effects of sunlight, moisture, and temperature on decay rates. A general linear model (GLM) framework was used to determine decay rates. Shading significantly decreased the decay rate of theE. colipopulation (P< 0.0001), with a rate of −0.176 day−1for the shaded treatment and −0.297 day−1for the unshaded treatment. Shading had no significant effect on decay rates of enterococci, CowM3, Rum-2-bac, and GenBac (P> 0.05). In addition,E. colipopulations showed a significant growth rate (0.881 day−1) in the unshaded samples during the first 5 days after deposition. UV-B was the most important parameter explaining the decay rate ofE. colipopulations. A comparison of the decay behaviors among all markers indicated that enterococcus concentrations exhibit a better correlation with the MST markers thanE. coliconcentrations. Our results indicate that bovine-associated MST markers can survive in cow pats for at least 1 month after excretion, and although their decay dynamic differs from the decay dynamic ofE. colipopulations, they seem to be reliable markers to use in combination with enterococci to monitor fecal pollution from pasture lands.


2012 ◽  
Vol 78 (8) ◽  
pp. 2569-2577 ◽  
Author(s):  
Beth L. Mote ◽  
Jeffrey W. Turner ◽  
Erin K. Lipp

ABSTRACTEnterococci are used to evaluate recreational-water quality and health risks in marine environments. In addition to their occurrence in feces of warm blooded animals, they are also common epiphytes. We investigated the contribution of plankton- or particle-associated enterococci in estuarine and coastal water. Seven water and size-fractionated plankton samples were collected monthly between April 2008 and January 2009 in the tidal reaches of the Skidaway River (Georgia, USA). Each size fraction, along with filtered (<30 μm) and bulk estuarine water, was processed according to U.S. Environmental Protection Agency method 1600. Presumptive enterococci were selected and species were identified using carbon substrate utilization patterns. The highest average densities occurred within the 30-, 63-, 105-, and 150-μm size fractions, which also represented the majority (>99%) of the particles within the sampled water. Particle-associated enterococci accounted for as little as 1% of enterococci in bulk water in April to as much as 95% in July.Enterococcus faecaliswas the most commonly isolated species from both water and plankton and represented 31% (16/51) and 35% (6/17) of the identifiedEnterococcusspecies from water and plankton, respectively.Enterococcus casseliflavusrepresented 29% of the selected isolates from plankton and 16% from water. BothE. faecalisandE. casseliflavuswere able to survive and grow in plankton suspensions significantly longer than in artificial seawater.Enterococcusspp. may be highly concentrated in plankton and associated particles, especially during summer and fall months. These findings could have implications for the effectiveness of enterococci as an indicator of coastal water quality, especially in particle-rich environments.


2012 ◽  
Vol 78 (19) ◽  
pp. 7166-7169 ◽  
Author(s):  
Reagan R. Converse ◽  
Larry J. Wymer ◽  
Alfred P. Dufour ◽  
Timothy J. Wade

ABSTRACTFew studies have addressed the efficacy of composite sampling for measuring indicator bacteria by quantitative PCR (qPCR). We compared results from composited samples with multiple-sample means for culture- and qPCR-based water quality monitoring. Results from composited samples for both methods were similarly correlated to multiple-sample means and predicted criteria exceedances equally.


2011 ◽  
Vol 77 (12) ◽  
pp. 3988-3997 ◽  
Author(s):  
Dustin K. Goto ◽  
Tao Yan

ABSTRACTHigh levels ofEscherichia coliwere frequently detected in tropical soils in Hawaii, which present important environmental sources ofE. colito water bodies. This study systematically examinedE. coliisolates from water and soil of several watersheds in Hawaii and observed high overall genotypic diversity (35.5% unique genotypes). In the Manoa watershed, fewer than 9.3% of the observedE. coligenotypes in water and 6.6% in soil were shared between different sampling sites, suggesting the lack of dominant fecal sources in the watershed. High temporal variability ofE. coligenotypes in soil was also observed, which suggests a dynamicE. colipopulation corresponding with the frequently observed high concentrations in tropical soils. WhenE. coligenotypes detected from the same sampling events were compared, limited sharing between the soil and water samples was observed in the majority of comparisons (73.5%). However, several comparisons reported up to 33.3% overlap ofE. coligenotypes between soil and water, illustrating the potential for soil-water interactions under favorable environmental conditions. In addition, genotype accumulation curves forE. colifrom water and soil indicated that the sampling efforts in the Manoa watershed could not exhaust the overall genotypic diversity. Comparisons ofE. coligenotypes from other watersheds on Oahu, Hawaii, identified no apparent grouping according to sampling locations. The results of the present study demonstrate the complexity of usingE. colias a fecal indicator bacterium in tropical watersheds and highlight the need to differentiate environmental sources ofE. colifrom fecal sources in water quality monitoring.


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