Pathogen Sources Estimation and Scenario Analysis Using the Soil and Water Assessment Tool (SWAT)

Concerns over water quality in Ireland have increased in recent years, in part due to the more frequent contamination of drinking water by pathogens such as Escherichia coli and Cryptosporidium. The objective of this study was to assess the use of SWAT for pathogen source estimation and to analyze the effects of various source scenarios on pathogen outputs in Irish catchments. Two agricultural catchments in Ireland susceptible to pathogen contamination of source water were the center of the SWAT model development with the primary focus on levels of E. coli in surface water. Model simulations used site and source specific information which was analyzed considering the total E. coli count for the simulation period (Fergus: January 2005–October 2006; Kilshanvey: January 2006–July 2007). Pathogen source estimation identified point sources as the most significant contributors to E. coli output with direct deposition the primary contributor (95%) in Kilshanvey and wastewater treatment plant outflow (89%) the main contributor in the Fergus catchment. A scenario analysis evaluated possible situations that may occur in study locations. The analysis indicated that restriction of livestock access to water sources and improved wastewater treatment would represent effective methods of improving water quality in both catchments.     

Modeling of Pathogen Indicator Organisms in a Small-Scale Agricultural Catchment Using SWAT

Degradation of water quality from microbial contaminants associated with agricultural activities has significant implications for source protection of potable water. Novel environmental approaches must be adopted to assess risks from waterborne pathogenic microbes. The objective of this study was to evaluate applicability of the Soil and Water Assessment Tool (SWAT) to predict daily concentrations of E. coli in a small-scale agricultural catchment in Ireland. The study area is based on the Kilshanvey catchment located in the west of Ireland. E. coli data (n = 25) from June 2006 to June 2007 were utilized for comparison with the model's predictions. Statistical analysis indicates an unsatisfactory to fair level of correlation for the model's predictions (R² = 0.03–0.35, NSE = –0.42–0.29). A sensitivity analysis identified direct stream deposition and die-off rates for E. coli as having a significant impact on the model's predictions. Our results suggest that the model is adequate to assess the magnitude of various microbial sources within catchments but capability to replicate daily observations is uncertain. However, model outputs could provide adequate data to develop a human exposure assessment to pathogen indicator organisms in surface water and assist policy-makers in developing appropriate risk management strategies.     

Antibiotic resistance profiles of <Emphasis Type="Italic">Escherichia coli</Emphasis> isolates from river sources in Durban,South Africa

Lack of access to potable water has forced many inhabitants of informal settlements in South Africa to rely on surface water sources for their daily water needs, thus exposing these communities to microbial contamination that can result in water-borne diseases. These water sources also serve as natural habitats of pathogenic E. coli strains which harbour virulence factors, which could play a role in the disease process, as well as various multi-drug resistant water-borne pathogens. This study investigated the microbiological quality of two river waters in Durban, South Africa, using total coliform and faecal coliform population as indices. The virulence markers and antibiogram profiles of the E. coli isolates from these rivers were also determined. The results indicated that water from these river sources were of poor microbiological quality and unfit for human consumption. Antibiotic Resistance Profiles of the isolates revealed that 97.1% of the Palmiet River isolates and 71.15% of the Umgeni River isolates were multi-resistant to the antibiotics tested, with all the isolates found to be resistant to novobiocin. Characterization of the virulence markers revealed the presence of stx1, cnf1 and eaeA genes, indicating the possible health risk associated with the ingestion of water from these rivers. The inherent health risks associated with the use of these river water emphasises the need for safe water supply and provision of proper sanitation facilities for the inhabitants of the informal settlements along these river banks.     

Escherichia coli and enterococci are sensitive and reliable indicators for human,livestock and wildlife faecal pollution in alpine mountainous water resources

Aims: This study evaluated the applicability of standard faecal indicator bacteria (SFIB) for alpine mountainous water resources monitoring. Methods and Results: Escherichia coli, enterococci (ENTC) and Clostridium perfringens were investigated by standard or frequently applied phenotypic and genotypic methods in a broad range of animal and human faecal sources in a large alpine mountainous area. Clostridium perfringens occurred only in human, livestock and carnivorous source groups in relevant average concentrations (log 4·7–7·0 CFU g^?1) but not in herbivorous wildlife sources. Escherichia coli proved to be distributed in all faecal source groups with remarkably balanced average concentrations (log 7·0–8·4 CFU g^?1). Except for single faecal samples from the cattle source group, prevalence rates for ENTC source groups were generally >87% with average concentrations of log 5·3–7·7 CFU g^?1. To test the faecal indication capacity in the environment, faecal prevalence data were comparatively analysed with results from the concurrently performed multi‐parametric microbial source tracking effort on karst spring water quality from the investigated alpine mountainous catchment ( Reischer et al. 2008 ; Environ Microbiol 10:2598–2608). Conclusion: Escherichia coli and enterococci are reliable faecal indicators for alpine mountainous water resources monitoring, although E. coli is the more sensitive one. Clostridium perfringens did not prove to be an indicator of general faecal pollution but is suggested a conservative microbial source tracking marker for anthropogenic faecal influence. Significance and Impact of the Study: Applicability of SFIB is currently hotly debated. This is the first study providing comprehensive information on the applicability of SFIB at alpine mountainous habitats.     

Fate of Escherichia coli O145 present naturally in bovine slurry applied to vegetables before harvest,after washing and simulated wholesale and retail distribution

Aims

To determine the fate of Escherichia coli on vegetables that were processed through commercial wash treatments and stored under simulated retail conditions at 4°C or wholesale at fluctuating ambient temperatures (0–25°C, dependent on season).

Methods and Results

Bovine slurry that was naturally contaminated with E. coli O145 was applied without dilution or diluted 1:10 using borehole water to growing potatoes, leeks or carrots. Manure was applied 1 week prior to harvest to simulate a near‐harvest contamination event by manure deposition or an application of contaminated water to simulate a flooding event or irrigation from a contaminated water source. At harvest, crops were contaminated at up to 2 log cfu g^?1. Washing transferred E. coli into the water of a flotation tank used for potato washing and did not completely remove all traces of contamination from the crop. Manure‐contaminated potatoes were observed to contain 0·72 cfu E. coli O145 g^?1 after processing and retail storage. Manure‐contaminated leeks harboured 0·73–1·55 cfu E. coli O145 g^?1 after washing and storage. There was no cross‐contamination when leeks were spray washed. Washing in an abrasive drum resulted in less than perfect decontamination for manure‐contaminated carrots. There were five post‐distribution isolations from carrots irrigated with contaminated water 24 h prior to harvest.

Conclusions

Standard commercial washing and distribution conditions may be insufficient to reliably control human pathogenic E. coli on fresh produce.

Significance and Impact

Previous speculation that the cause of a UK foodborne disease outbreak was soil from imperfectly cleaned vegetables is plausible.     

Microbial contamination in kitchens and bathrooms of rural Cambodian village households

Aims: To quantify microbial contamination on kitchen and bathroom surfaces (fomites) in rural Cambodian homes and to compare these concentrations to similar data from the United States and Japan. Methods and Results: This study monitored the numbers of faecal coliforms (i.e. thermotolerant coliforms), total coliforms, Escherichia coli and heterotrophic plate count bacteria on household surfaces in a rural village of Cambodia. Faecal coliform levels in Cambodia were highest on moist locations such as the plastic ladle used for sink water, the toilet seat surface and the cutting board surface with 100‐fold higher levels of faecal coliform bacteria than E. coli and 100‐fold higher levels of faecal coliforms than the US and Japanese studies. Conclusions: A single public health intervention barrier, such as an improved latrine, is only partially effective for household sanitation. For complete sanitation, multiple environmental barriers may be necessary. These barriers occur in a house constructed with easily washable surfaces, a chlorinated water distribution system, house climate control and cleaning product availability. Significance and Impact of the Study: Results of this study can be used to emphasize the importance of increasing household environmental sanitation barriers.     

Evaluating Spatial and Temporal Variability of Fecal Coliform Bacteria Loads at the Pelahatchie Watershed in Mississippi

Bacterial contaminations of surface waters are an increasing concern for scientists and public health agencies because pathogenic bacteria can cause adverse effects on human health. This research was performed to investigate spatial and seasonal variability of fecal coliform bacteria (FCB) concentrations in the Pelahatchie watershed (527 km²) in Mississippi, USA. Livestock manure, poultry litter, and effluent from failing septic systems were identified as major sources of FCB in the Pelahatchie watershed. The Soil and Water Assessment Tool (SWAT)/microbial sub-model was applied, and model-simulated FCB concentrations were compared with the monthly measured FCB concentrations (years 2001–2008) at the outlet of the watershed. New methodologies were introduced to incorporate bacteria loads into the bacteria model. Results showed coefficients of determination (R ²) of 0.71 to 0.75, and Nash-Sutcliffe efficiency index (NSE) of 0.67 to 0.75 during the bacteria model's calibration and validation periods, respectively. Seasonal analysis of the model-simulated results determined the highest bacteria concentrations in January, whereas the lowest concentrations were simulated in June. Furthermore, the FCB contributions to the watershed outlet from the sources of contamination varied with time of year. This study will help watershed managers to implement best management practices for improvement of water quality.     

False‐negative β‐d‐glucuronidase reactions in membrane lactose glucuronide agar medium used for the simultaneous detection of coliforms and Escherichia coli from water

Aims: Testing for β‐d ‐glucuronidase activity has become the basis of many methods for the detection of Escherichia coli in both food and water. Used in combination with tests for the presence of β‐d ‐glucuronidase, these tests offer a simple method for simultaneously detecting coliforms and E. coli. The purpose of this study was to determine the effectiveness of several different procedures in detecting β‐d ‐glucuronidase activity and hence in detecting E. coli. Methods and Results: The ability of membrane lactose glucuronide agar (MLGA), Colilert‐18^®, MI agar, Colitag^® and Chromocult agar to detect β‐d ‐glucuronidase activity was tested with over 1000 isolates of E. coli recovered from naturally contaminated water samples. Four of the media gave very similar results but MLGA failed to detect glucuronidase activity in 15·6% of the cultures tested. Conclusions: MLGA had very poor sensitivity for the detection of β‐d ‐glucuronidase activity in strains of E. coli isolated from naturally contaminated water. This is probably because of the fact that β‐d ‐glucuronidase activity is pH‐sensitive and that acid is formed by E. coli during fermentation of lactose in MLGA. Significance and Impact of the Study: The detection of E. coli in drinking water is the primary test used to establish faecal contamination. The poor sensitivity of MLGA in detecting β‐d ‐glucuronidase activity suggests that this medium and others containing high concentrations of fermentable carbohydrate should not be used for the detection of E. coli.     

A rapid and simple PCR method for identifying isolates of the genus Azospirillum within populations of rhizosphere bacteria

Aims: Escherichia coli is the pre‐eminent microbiological indicator used to assess safety of drinking water globally. The cost and equipment requirements for processing samples by standard methods may limit the scale of water quality testing in technologically less developed countries and other resource‐limited settings, however. We evaluate here the use of ambient‐temperature incubation in detection of E. coli in drinking water samples as a potential cost‐saving and convenience measure with applications in regions with high (>25°C) mean ambient temperatures. Methods and Results: This study includes data from three separate water quality assessments: two in Cambodia and one in the Dominican Republic. Field samples of household drinking water were processed in duplicate by membrane filtration (Cambodia), Petrifilm? (Cambodia) or Colilert^® (Dominican Republic) on selective media at both standard incubation temperature (35–37°C) and ambient temperature, using up to three dilutions and three replicates at each dilution. Matched sample sets were well correlated with 80% of samples (n = 1037) within risk‐based microbial count strata (E. coli CFU 100 ml^?1 counts of <1, 1–10, 11–100, 101–1000, >1000), and a pooled coefficient of variation of 17% (95% CI 15–20%) for paired sample sets across all methods. Conclusions: These results suggest that ambient‐temperature incubation of E. coli in at least some settings may yield sufficiently robust data for water safety monitoring where laboratory or incubator access is limited. Significance and Impact of the Study: Ambient‐temperature incubation of E. coli may be a promising option for reducing the complexity and costs associated with water safety monitoring for faecal indicator bacteria such as E. coli in a field context in resource‐limited settings, as are often encountered in developing countries and after disasters.     

Tubewell water quality and predictors of contamination in three flood-prone areas in Bangladesh

Aims: To measure enteric bacterial contamination of tubewells in three flood prone areas in Bangladesh and the relationship of bacteriological contamination with tubewell sanitary inspection scores. Methods and Results: Microbiologists selected 207 tubewells in three flood prone districts, assessed physical characteristics of the tubewells and collected a single water sample from each tubewell. Tubewell water samples were contaminated with total coliforms (41%, n = 85), thermotolerant coliforms (29%, n = 60) and Escherichia coli (13%, n = 27). Among contaminated wells, the median CFU of contamination per 100 ml was 8 (interquartile range, 2–30) total coliforms, 5 (interquartile range, 2–23) thermotolerant coliforms and 6 (interquartile range, 1–30) E. coli. There was no significant association between tubewell contamination with E. coli, thermotolerant coliforms or total coliforms and a poor sanitary inspection score, though a history of inundation was associated with contamination with both E. coli and thermotolerant coliforms. Conclusions: Tubewells in flood-prone regions of Bangladesh were commonly contaminated with low levels of faecal organisms, contamination that could not be predicted by examining the tubewell’s external characteristics. Significance and Impact of the Study: The forms currently used for sanitary inspection do not identify the most important causes of drinking water contamination in these communities.     

Concentration of Escherichia coli in sediments as an indicator of the sanitary status of oyster (Crassostrea virginica) aquaculture sites

The objective of the study was to determine whether there are differences in Escherichia coli counts in relation to seasonal and/or spatial distribution patterns in a conditional shellfish‐growing zone located in the Richibucto estuary, New Brunswick, Canada. E. coli concentrations in surface water, sediments, suspended and bottom cultured American oysters (Crassostrea virginica) were determined. Contamination levels in water were significantly lower than in sediments, bottom and suspended cultured oysters (P < 0.01; P < 0.05, P < 0.01, n = 303, respectively). No significant difference in fecal contamination was observed between suspended and bottom cultured oysters (P > 0.05, n = 303). Seasonal variations (temporal) had a significant influence on fecal coliform contamination of all components (P < 0.01, n = 303, linear model). E. coli concentration levels were as much as ten times higher in sediments than in water. Furthermore, results suggest that E. coli concentration levels in sediments are a more reliable indicator of the sanitary status of a grow‐out operation than E. coli levels in water. Considering only sampling dates when contamination levels in oysters exceeded the established threshold of 230 MPN, less than 50% of the cases were predicted by water contamination while as many as 89.9% of the samples were predicted by sediment contamination using the proposed threshold of 75 MPN per 100 g. This paper emphasizes the importance of acknowledging the significant role sediments play in the dynamics of contamination by E. coli in areas that are currently exploited or are being considered for shellfish aquaculture. The presence of E. coli in sediments should not be overlooked as an integral factor in assessing the environmental sanitary status.     

Genetic diversity and antimicrobial resistance of Escherichia coli from human and animal sources uncovers multiple resistances from human sources

Escherichia coli are widely used as indicators of fecal contamination, and in some cases to identify host sources of fecal contamination in surface water. Prevalence, genetic diversity and antimicrobial susceptibility were determined for 600 generic E. coli isolates obtained from surface water and sediment from creeks and channels along the middle Santa Ana River (MSAR) watershed of southern California, USA, after a 12 month study. Evaluation of E. coli populations along the creeks and channels showed that E. coli were more prevalent in sediment compared to surface water. E. coli populations were not significantly different (P = 0.05) between urban runoff sources and agricultural sources, however, E. coli genotypes determined by pulsed-field gel electrophoresis (PFGE) were less diverse in the agricultural sources than in urban runoff sources. PFGE also showed that E. coli populations in surface water were more diverse than in the sediment, suggesting isolates in sediment may be dominated by clonal populations.Twenty four percent (144 isolates) of the 600 isolates exhibited resistance to more than one antimicrobial agent. Most multiple resistances were associated with inputs from urban runoff and involved the antimicrobials rifampicin, tetracycline, and erythromycin. The occurrence of a greater number of E. coli with multiple antibiotic resistances from urban runoff sources than agricultural sources in this watershed provides useful evidence in planning strategies for water quality management and public health protection.     

Detection of E. coli O157:H7 by immunomagnetic separation coupled with fluorescence immunoassay

Conventional culture-based methods for detection of E. coli O157:H7 in foods and water sources are time-consuming, and results can be ambiguous, requiring further confirmation by biochemical testing and PCR. A rapid immunoassay prior to cultivation to identify presumptive positive sample would save considerable time and resources. Immunomagnetic separation (IMS) techniques are routinely used for isolation of E. coli O157:H7 from enriched food and water samples, typically in conjunction with cultural detection followed by biochemical and serological confirmation. In this study, we developed a new method that combines IMS with fluorescence immunoassay, termed immunomagnetic fluorescence assay (IMFA), for the detection of E. coli O157:H7. E. coli O157:H7 cells were first captured by anti-O157 antibody-coated magnetic beads and then recognized by a fluorescent detector antibody, forming an immunosandwich complex. This complex was subsequently dissociated for measurement of fluorescence intensity with Signalyte™-II spectrofluorometer. Experiments were conducted to evaluate both linearity and sensitivity of the assay. Capture efficiencies were greater than 98%, as determined by cultural plating and quantitative real-time PCR, when cell concentrations were <10⁵ cells/mL. Capture efficiency decreased at higher cell concentrations, due to the limitation of bead binding capacity. At lower cell concentrations (10–10⁴ cells/mL), the fluorescence intensity of dissociated Cy5 solution was highly correlated with E. coli 157:H7 cell concentrations. The detection limit was 10 CFU per mL of water. The assay can be completed in less than 3 h since enrichment is not required, as compared to existing techniques that typically require a 24 h incubation for pre-enrichment, followed by confirmatory tests.     

The prevalence and antimicrobial resistance phenotypes of Salmonella,Escherichia coli and Enterococcus sp. in surface water

Surface water is prone to bacterial contamination as it receives wastes and pollutants from human and animal sources, and contaminated water may expose local populations to health risks. This review provides a brief overview on the prevalence and antimicrobial resistance (AR) phenotypes of Salmonella, Escherichia coli and Enterococcus, found in natural freshwaters. These bacteria are frequently detected in surface waters, sometimes as etiological agents of waterborne infections, and AR strains are not uncommonly identified in both developed and developing countries. Data relating to Salmonella, E. coli and Enterococcus present in environmental water are lacking, and in order to understand their development and dissemination using the One Health approach, understanding the prevalence, distribution and characteristics of the bacteria present in surface water as well as their potential sources is important. Furthermore, AR bacteria in natural watersheds are not well investigated and their impacts on human health and food safety are not well understood. As surface water is a receptacle for AR bacteria from human and animal sources and a vehicle for their dissemination, this is a crucial data gap in understanding AR and minimizing its spread. For this review, Salmonella, E. coli and Enterococcus were chosen to evaluate the presence of primary pathogens and opportunistic pathogens as well as to monitor AR trends in the environmental water. Studies around the world have demonstrated the widespread distribution of pathogenic and AR bacteria in surface waters of both developing and developed countries, confirming the importance of environmental waters as a reservoir for these bacteria and the need for more attention on the environmental bacteria for emerging AR.     

Chemiluminescence detection of Escherichia coli in fresh produce obtained from different sources

A chemiluminescence‐based assay is developed for the rapid detection of Escherichia coli in fresh produce. The assay was based on the reaction of β‐galactosidase enzyme from E. coli with a phenylgalactosidase‐substituted dioxetane substrate. Light emitted from the reaction was measured in a luminometer and data correlated with counts of E. coli enumerated on sorbitol–MacConkey agar plates. A strain of E. coli O157:H7 was used to inoculate samples of fresh produce to differentiate the inoculum from the natural E. coli potentially present on the produce. Fresh market samples were tested for generic E. coli and E. coli O157:H7. Signi?cant differences in light emission were found in samples with high initial E. coli counts when market samples were compared to respective heat‐treated samples. The assay was able to detect E. coli in all produce tested, particularly at higher contamination or inoculation levels. The sensitivity of the assay ranged between 10²–10⁵ CFU within 30 min. The chemiluminescence assay provides a simple and rapid method for detection of viable E. coli, an important step towards enhancing food safety. Copyright © 2004 John Wiley & Sons, Ltd.     

Use of zero-valent iron biosand filters to reduce Escherichia coli O157:H12 in irrigation water applied to spinach plants in a field setting

Aims:  Zero‐valent iron (ZVI) filters may provide an efficient method to mitigate the contamination of produce crops through irrigation water. Methods:  A field‐scale system was utilized to evaluate the effectiveness of a biosand filter (S), a biosand filter with ZVI incorporated (ZVI) and a control (C, no treatment) in decontaminating irrigation water. An inoculum of c. 8·5 log CFU 100 ml^?1 of Escherichia coli O157:H12 was introduced to all three column treatments in 20‐l doses. Filtered waters were subsequently overhead irrigated to ‘Tyee’ spinach plants. Water, spinach plant and soil samples were obtained on days 0, 1, 4, 6, 8, 10, 13 and 15 and analysed for E. coli O157:H12 populations. Results:  ZVI filters inactivated c. 6 log CFU 100 ml^?1E. coli O157:H12 during filtration on day 0, significantly (P < 0·05) more than S filter (0·49 CFU 100 ml^?1) when compared to control on day 0 (8·3 log CFU 100 ml^?1). On day 0, spinach plants irrigated with ZVI‐filtered water had significantly lower E. coli O157 counts (0·13 log CFU g^?1) than spinach irrigated with either S‐filtered (4·37 log CFU g^?1) or control (5·23 log CFU g^?1) water. Soils irrigated with ZVI‐filtered water contained E. coli O157:H12 populations below the detection limit (2 log CFU g^?1), while those irrigated with S‐filtered water (3·56 log CFU g^?1) were significantly lower than those irrigated with control (4·64 log CFU g^?1). Conclusions:  ZVI biosand filters were more effective in reducing E. coli O157:H12 populations in irrigation water than sand filters. Significance and Impact of the Study:  Zero‐valent ion treatment may be a cost‐effective mitigation step to help small farmers reduce risk of foodborne E. coli infections associated with contamination of leafy greens.     

Assessment of shallow groundwater quality and its suitability for drinking purpose near the Béni-Mellal wastewater treatment lagoon (Morocco)

Abstract

The present study aimed to evaluate the suitability for drinking purpose of shallow groundwater near the Béni-Mellal wastewater treatment lagoon based on various physicochemical, heavy metals, and bacteriological parameter analyses. The physicochemical results revealed that some of the samples do not comply with the Moroccan and/or WHO standards for drinking water. Parameters including turbidity, TH, Na⁺, Li⁺, Ba²⁺, Ca²⁺ (～47.1% of samples), Cd (～52.9% of samples), Fe (～82.4% of samples), Pb (～58.8% of samples), T. coliforms, and E. coli exceeded the drinking limits. The statistical analyses revealed that the shallow groundwater chemistry is mainly controlled by geogenic and anthropogenic sources. For quality assessment, using the Moroccan groundwater assessment grid, the values of EC and Cl^–, NO₃^–, NH₄⁺, oxidability, and E. coli, fixed as pollution indicators, showed that most of the wells showed medium-to-poor quality, 14% of them have a very poor water quality, and 20% of them belong to the bad water quality. According to geometric and arithmetic DWQI values, the groundwater quality was frequently fair to good, needing treatment or at least disinfection before public consumption. A sensitivity analysis results indicated that Fe, Cd, Cr, Pb, and E. coli have an important impact on the DWQI computing.     

Host Species-Specific Metabolic Fingerprint Database for Enterococci and Escherichia coli and Its Application To Identify Sources of Fecal Contamination in Surface Waters

A metabolic fingerprint database of enterococci and Escherichia coli from 10 host groups of animals was developed to trace the sources of fecal contamination in surface waters. In all, 526 biochemical phenotypes (BPTs) of enterococci and 530 E. coli BPTs were obtained from 4,057 enterococci and 3,728 E. coli isolates tested. Of these, 231 Enterococcus BPTs and 257 E. coli BPTs were found in multiple host groups. The remaining 295 Enterococcus BPTs and 273 E. coli BPTs were unique to individual host groups. The database was used to trace the sources of fecal contamination in a local creek. The mean diversities (Di) of enterococci (Di = 0.76 ± 0.05) and E. coli (Di = 0.88 ± 0.04) were high (maximum 1) in water samples, indicating diverse sources of fecal contamination. Overall, 71% of BPTs of enterococci and 67% of E. coli BPTs from water samples were identified as human and animal sources. Altogether, 248 Enterococcus BPTs and 282 E. coli BPTs were found in water samples. Among enterococci, 26 (10%) BPTs were identical to those of humans and 152 BPTs (61%) were identical to those of animals (animal BPTs). Among E. coli isolates, 36 (13%) BPTs were identical to those of humans and 151 (54%) BPTs were identical to those of animals. Of the animal BPTs, 101 (66%) Enterococcus BPTs and 93 (62%) E. coli BPTs were also unique to individual animal groups. On the basis of these unique Enterococcus BPTs, chickens contributed 14% of contamination, followed by humans (10%), dogs (7%), and horses (6%). For E. coli, humans contributed 13% of contamination, followed by ducks (9%), cattle (7%), and chickens (6%). The developed metabolic fingerprint database was able to distinguish between human and animal sources as well as among animal species in the studied catchment.     

A survey of enteric bacteria and protozoans in fresh bovine faeces on New Zealand dairy farms

Aims: To determine the counts and/or prevalence in fresh bovine faeces of Escherichia coli, enterococci, Campylobacter, Salmonella, shiga toxin‐producing E. coli (STEC), Giardia and Cryptosporidium, as inputs to numerical models designed to estimate microbial loadings on pasture grazed by cattle in New Zealand. Methods and Results: In each season over one year, samples of freshly deposited bovine faeces were collected from four New Zealand dairy farms (n = 155), and enumerated for E. coli, enterococci, Campylobacter, Giardia and Cryptosporidium. They were also tested for the presence of Salmonella and STEC. The overall median bacterial counts (g^?1 wet weight) were E. coli– 5·9 × 10⁶; enterococci – 1·3 × 10⁴; Campylobacter– 3·9 × 10⁵. All counts were highly variable within and between samplings, and few seasonal or regional patterns emerged. However, mean Campylobacter counts were consistently higher in spring. No Salmonella spp. was detected, and only two samples were positive for STEC. Cryptosporidium and Giardia were isolated from 5·2% and 4·5% of the samples, respectively, yielding low numbers of (oo)cysts (1–25 g^?1 and 1–17 g^?1, respectively). Conclusions: Fresh bovine faeces are a significant source of E. coli, enterococci and Campylobacter on New Zealand pastures, although numbers are likely to vary markedly between faecal samples. Significance and Impact of the Study: The study provides the first significant set of indicator and pathogen counts for one of the largest sources of faecal contamination of natural waters in New Zealand, and will be used to model these inputs.     

Evidence for Coexistence of Distinct Escherichia coli Populations in Various Aquatic Environments and Their Survival in Estuary Water

Escherichia coli, a commensal bacterium from the intestinal tracts of humans and vertebrate animals, has been used as one of two bacterial indicators of fecal contamination, along with intestinal enterococci, to monitor the microbiological quality of water. However, water environments are now recognized as a secondary habitat where some strains can survive. We investigated the survival of E. coli isolates collected from bodies of water in France exhibiting distinct profiles of contamination, defined according to the following criteria: vicinity of the point sources of contamination, land use, hydrology, and physicochemical characteristics of the receiving water. We selected 88 E. coli strains among a collection of 352 strains to carry out a microcosm experiment in filtered estuarine water for 14 days at 10°C. The relationship between the survival of E. coli strains and genotypic and phenotypic characteristics was analyzed. This work showed that distinct E. coli survival types, able to survive from between 7 and 14 days to less than 2 days, coexisted in the water. E. coli isolates that rapidly lost their culturability were more frequently isolated in water recently contaminated by fecal bacteria of human origin, and most were multiresistant to antibiotics and harbored several virulence factors. In contrast, persistent strains able to survive from 4 to 14 days were more often found in water with low levels of fecal bacteria, belonged mainly to the B1 phylogroup, often harbored only one virulence factor, kspE or ompT, and were able to grow at 7°C.