In vitro invasiveness and intracellular survival of Salmonella strains isolated from the aquatic environment

Salmonella has a life cycle between the host and the external environment where it is exposed to stressful conditions that may affect its virulence. In this study, we compared the capability of two aquatic (S. Oranienburg S76 and Saintpaul S70) and one clinical isolates (S. Oranienburg S347) to adhere and invade epithelial cells, and to survive within macrophages. S76 and S70, were less adherent to Caco‐2 cells than S347, but they were more invasive. The intracellular survival and growth of S76 in macrophages was increased with time, while S347 showed the highest peak value and S70 survived at moderate levels. Induced cell death in infected epithelial cells and macrophages revealed no differences between all strains. In conclusion, the contrasting responses detected between environmental and clinical isolates could indicate the importance of the distinct adaptation conditions of the strains to the isolation environment that could differentially affect their interaction with the host.     

Distribution of antimicrobial resistant Salmonella in an urban river that flows through the provincial city of Miyazaki,Japan

There is limited information regarding antimicrobial resistant Salmonella in the aquatic environment. In this study, we investigated the distribution of antimicrobial resistant Salmonella in the Yae River at sites upstream, midstream and downstream of the urban area of Miyazaki City, Japan. Pulsed field gel electrophoresis was performed to evaluate the genetic relationship among antimicrobial resistant Salmonella. The percentage of isolates that were resistant to at least one antimicrobial agent in upstream, midstream, and downstream sites was 23% (resistant isolates/total isolates = 11/44), 3% (1/34) and 32% (12/38), respectively. The 11 isolates of multidrug‐resistant Salmonella collected from downstream were classified to have a common genetic pattern belonging to the same cluster with a 100% similarity level. The multidrug‐resistant Salmonella were obtained from an identical source and were present in an urban river near human habitation.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—III: Phenols and aromatic acids in polluted and unpolluted waters

Phenols and aromatic acids were analysed in polluted river waters in the Tokyo area and in water from an unpolluted river, brook, reservoir and in pond waters from the Ogasawara (Bonin) Islands. The phenolic acids (p-hydroxybenzoic, vanillic, syringic, p-coumaric and ferulic acids) and o- and m-hydroxybenzoic acids were found in the waters of the Tokyo area and Ogasawara Islands at a concentration of generally less than 1 μg 1⁻¹, but pentachlorophenol, bisphenol A, terephthalic and trimesic acids were not identified in the waters of the Ogasawara Islands. It was confirmed that the major sources of these phenolic acids are vascular plants and their detritus, while pentachlorophenol, bisphenol A and terephthalic acids are mainly attributed to human activities. It was also established that these phenolic acids are commonly distributed in polluted and unpolluted waters.The p-coumaric and ferulic acids as carbon (CFC)/total organic carbon and CFC/extractable organic carbon with ethyl acetate values suggested that the contribution of vascular plants and their detritus to the waters between the Tokyo area and Ogasawara Islands are near equal. According to the syringic acid/vanillic acid ratios, it is probable that the relative contribution of angiosperms to gimnosperms for the waters of the Tokyo area is smaller than those of the Ogasawara Islands.     

Evaluation of different analysis and identification methods for Salmonella detection in surface drinking water sources

The standard method for detecting Salmonella generally analyzes food or fecal samples. Salmonella often occur in relatively low concentrations in environmental waters. Therefore, some form of concentration and proliferation may be needed. This study compares three Salmonella analysis methods and develops a new Salmonella detection procedure for use in environmental water samples. The new procedure for Salmonella detection include water concentration, nutrient broth enrichment, selection of Salmonella containing broth by PCR, isolation of Salmonella strains by selective culture plates, detection of possible Salmonella isolate by PCR, and biochemical testing. Serological assay and pulsed-field gel electrophoresis (PFGE) can be used to identify Salmonella serotype and genotype, respectively. This study analyzed 116 raw water samples taken from 18 water plants and belonging to 5 watersheds. Of these 116, 10 water samples (8.6%) taken from 7 water plants and belonging to 4 watersheds were positive for a Salmonella-specific polymerase chain reaction targeting the invA gene. Guided by serological assay results, this study identified 7 cultured Salmonella isolates as Salmonella enterica serovar: Alnaby, Enteritidis, Houten, Montevideo, Newport, Paratyphi B var. Java, and Victoria. These seven Salmonella serovars were identified in clinical cases for the same geographical areas, but only one of them was 100% homologous with clinical cases in the PFGE pattern.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—II: Features of fatty acids for polluted and unpolluted waters

Fatty acids were analyzed for polluted river waters from the Tokyo area and unpolluted river, brook, reservoir and pond waters from the Ogasawara (Bonin) Islands to elucidate their features for polluted and unpolluted waters. Fatty acids ranging from the carbon chain length of C₈-C₃₄ including unsaturated and branched acids were found with the great predominance of even-carbon numbers and lower molecular weight ranges (C₁₃–C₁₉) in the water samples from the Tokyo area and Ogasawara Islands. It was thus confirmed that no marked changes in fatty acid composition between polluted and unpolluted waters are absent. However, the total contents of the acids (average, 270 ± 120 μg 1⁻¹ at 90% confidence limits) as well as the FAC (fatty acids as carbon)/TOC (total organic carbon, 2.6 ± 0.93%) and FAC/EOC (extractable organic carbon with ethyl acetate, 16 ± 6.7%) of river water samples from the Tokyo area were considerably higher than those of the waters from the Ogasawara Islands (58 ± 29 μg 1⁻¹, 0.79 ± 0.48% and 2.1 ± 0.51%, respectively). These higher values for the Tokyo area should be due to sewage.A filtering method showed that most of fatty acids (>95%) was present in particulate fractions. In addition, the content of free fatty acids was fairly lower than that of combined fatty acids. Further, unsaturated fatty acids were detected only in combined forms both in particulate and dissolved fractions. They are considered to be present as esters in polluted and unpolluted waters.     

Relevance of peat-draining rivers for the riverine input of dissolved iron into the ocean

Peat bogs have the ability to produce strong chelate ligands (humic and fulvic acids) which enhance the weathering rates of iron-silicate minerals and greatly increase the solubility of the essential trace metal iron in river water. Fluvial networks link peat bogs with the ocean, and thus terrestrial-derived fulvic-iron complexes fuel the ocean's biological productivity and biological carbon pump, but understanding this role is constrained by inconsistent observations regarding the behaviour of riverine iron in the estuarine mixing zone, where precipitation reactions remove iron from the water column. We applied a characterization of the colloidal iron carriers in peatland-draining rivers in North Scotland, using field-flow fractionation (FFF), in combination with end-member mixing experiments of river water sampled near the river mouth and coastal seawater using a ⁵⁹Fe radiotracer method. According to our results, the investigated river contributed “truly dissolved” Fe concentrations of about 3300 nmol L^− 1 to the ocean which is nearly two orders of magnitude higher than the dissolved iron contribution of the “average world” river (∼ 40 nmol L^− 1). Thus we conclude that peatland-draining rivers are important sources of dissolved iron to the ocean margins. We propose highly electrostatic and sterical stabilized iron-organic matter complexes in the size range of < 2 kDa to be responsible for iron transport across the estuarine mixing zone.     

Determination of mutagenic activity in salmonella of residual fulvic acids after ozonation

Residual organics of ozonated soil and water fulvic acids were tested for mutagenicity in the Salmonella: mammalian-microsome assay. A highly ozonated soil fulvic acid extract induced His reversion in Salmonella typhimurium strain TA100 only and did not require metabolic activation for the weak mutagenic response observed.     

Adsorption des acides humiques sur charbon active en poudre. Influence du triphosphate de sodium

The use of activated carbon beds for the removal of natural humic and fulvic substances found in water supplies, has recently received considerable attention in water treatment operation (Lee et al., 1980; Le Cloirec et al., 1983). Moreover, the use of carbon adsorption for the reduction of haloform precursors (Anderson et al., 1981) and trihalomethanes produced by chlorination process, has contributed to a comprehensive investigation of adsorption characteristics of natural organic compounds (McCreary and Snoeyink, 1981). Many recent works showed the influence of adsorption system characteristics, such as pH, salt type, salt concentration and ionic heterogeneity in multicomponent adsorption systems, on the removal efficiency of humic and fulvic substances by activated carbon (McCreary and Snoeyink, 1980; Randtke and Jepsen, 1982; Weber et al., 1983). The purpose of this study is to examine the effect of a main component of domestic detergents, sodium triphosphate (STP), on the adsorptive capacities of powdered activated carbon (PAC) for commercially supplied humic acids, at different pH values in distilled water. Also, the effect of STP concentration and pH on the adsorption affinity of the PAC for humic acids, is discussed in relation with electrokinetic properties of carbon particles (zeta potential measurements).A first batch equilibrium study (Figs 1 and 2), showed an effective enhancement of adsorption capacity for humic acids as a function of STP concentration, in a non buffered media (pH of distilled water, close to 5.0). For example, visible absorption analysis of humic acids indicates an increase of 93% (500 mg l⁻¹ PAC) and 133% (1000 mg l⁻¹ PAC) in the carbon adsorption efficiency for a STP concentration from 0.2 to 1.0mM. A second batch equilibrium study (Figs 3 and 4) led to adsorption isotherms for humic acids in distilled water, as a function of STP concentration and initial pH value of the non buffered multicomponent system. Freundlich isotherms showed an increase in the adsorption capacity of the PAC for humic acids, with a decrease in pH and an increase in STP concentration. However, the adsorption capacity for humic acids is quite reduced at high pH values in presence of STP, in comparison with results obtained with distilled water.Electrokinetic measurements on PAC suspensions (Fig. 5) indicates that both humic acids and STP induce a negative variation of the zeta potential of carbon particles. In such a binary system, the zeta potential is a linear function of the pH; the negative surface charge of the carbon increasing with an elevation of pH (Fig. 6). Therefore, it appears that some adsorption of triphosphate polyanion from solution could occur, contributing then to the apparent negative surface charge of PAC particles.It has been previously showed that the type of anion in sodium salts, had little effect on the enhancement of adsorptive capacities of activated carbon for humic substances (Lafrance and Mazet, 1985), due to Na⁺ ions. However, adsorption of TP anions on the carbon surface may produce a source of repulsive charges, unfavourable to the co-adsorption of humic acids as the pH of the binary system reach more basic conditions. The influence of possible electrostatic interactions between adsorbates at the carbon surface, on the adsorption efficiency for humic acids, could then be studied by zeta potential measurements of PAC particles during the adsorption process.     

Evaluation of host-specific Bacteroidales 16S rRNA gene markers as a complementary tool for detecting fecal pollution in a prairie watershed

Our ability to identify and eliminate fecal contamination of water, now and in the future, is essential to reduce incidences of waterborne disease. Bacterial source tracking is a recently developed approach for identifying sources of fecal pollution. PCR primers designed by Bernhard and Field [Bernhard, A.E., Field, K.G., 2000a. A PCR assay to discriminate human and ruminant feces on the basis of host differences in Bacteroides-Prevotella genes encoding 16S rRNA. Appl. Environ. Microbiol. 66(10), 4571-4574] and Dick et al. [Dick, L.K., Bernhard, A.E., Brodeur, T.J., Santo Domingo, J.W., Simpson, J.M., Walters, S.P., Field, K.G., 2005. Host distributions of uncultivated fecal Bacteroidales bacteria reveal genetic markers for fecal source identification. Appl. Environ. Microbiol. 71(6), 3184-3191] for the detection of human (HF183), pig (PF163) and ruminant (CF128) specific Bacteroidales 16s rRNA genetic markers were tested for their suitability in detecting fecal pollution in Saskatchewan, Canada. The sensitivity and specificity of these primers were assessed by testing eight raw human sewage samples and 265 feces from 12 different species in Saskatchewan. The specificity of each primer set was ≥94%. The accuracy of HF183 and PF163 to distinguish between the different species was 100%, whereas CF128 cross-reacted with 22% of the pig feces. Occurrence of the host-specific Bacteroidales markers and the conventional indicator Escherichia coli in relation to several enteropathogens was investigated in 70 water samples collected from different sites along the Qu'Appelle River (Saskatchewan, Canada). Human and ruminant fecal markers were identified in 41 and 14% of the water samples, respectively, whereas the pig marker was never detected in the river water. The largest concentrations in E. coli counts were concomitant to the simultaneous detection of HF183 and CF128. Thermotolerant Campylobacter spp., Salmonella spp. and Shiga toxin genes (stx1 and stx2)-positive E. coli (STEC) were detected in 6, 7 and 63% of the water samples, respectively. However, none of the stx positive water samples were positive for the E. coli O157:H7 gene marker (uidA). Odds ratios analysis suggests that CF128 may be predictive for the presence of Salmonella spp. in the river investigated. None of the fecal indicators were able to confidently predict the presence of thermotolerant Campylobacter spp. and STEC.     

Some effects of pulp and paper wastewater on microbiological water quality of a river

A study was conducted to detect the source of fecal indicator bacteria and measure the resulting impairment of water quality of the Sturgeon River at Sturgeon Falls, Ontario, Canada. The bacteriological water quality of the river above the dam at Sturgeon Falls was fairly good, while below the dam the water quality was degraded. The principal input of fecal indicator bacteria was traced to the paper mill at Sturgeon Falls. The impairment of water quality was detected all the way to recreational areas near the mouth of the river. The impaired stretch of the river had diminished aesthetic appeal. Other sources of indicator bacteria could be masked by the large numbers of similar bacteria discharged from the paper mill. The principal fecal coliform was Klebsiella pneumoniae. In pulp mill wastes the fecal origin of this bacterium can be disputed, and so its presence in large numbers interfered with the interpretation of fecal coliform results. K. pneumoniae is also an opportunistic pathogen which causes infections in humans. Thermotolerant oxidase positive bacteria which were isolated from the paper mill wastes, register as false positives in the fecal coliform test causing problems in interpretation. Pseudomonas aeruginosa was detected in the pulp mill wastewater, and at a level of 82 PA 100 ml⁻¹ in recreational areas of the river. This was considered to be of some hazard to users of the water. In addition, Escherichia coli was detected in the mill wastewater, at about 200 EC 100 ml⁻¹, and this probably indicated some measure of fecal pollution though likely of animal origin. Finally the nutrient rich wastewater led to an approx. 50-fold increase in density of aerobic heterotrophic bacteria in the river water, as well as the production of a slimy filamentous growth on surfaces, stones and wooden pilings, in the river. The principal organism in this slime was the fungus Leptomitus.     

Characterizing nutrient dynamics with relation to changes in partial pressure of CO2 in a tropical sewage‐fed aquaculture pond situated in a Ramsar wetland

The changes in nutrient dynamics (nitrate, ammonium, silicate, phosphate and iron concentration) vis‐à‐vis partial pressure of CO₂ in water [pCO₂(water)] from tropical sewage‐fed aquaculture ponds (East Kolkota Wetlands, India) were analysed by means of a microcosm. A significant relationship between these nutrient’s removal from the system and reduction in pCO₂(water) was observed (with few exceptions). These water bodies acted as significant sources of CO₂ in pre‐monsoon and monsoon seasons despite having substantial quantity of chlorophyll‐a to make it a net autotrophic system. The study revealed that if conditions favourable for optimum photosynthesis can be maintained in these ponds, the CO₂ source character of these ponds can be reversed. In the post‐monsoon season, when the pH of the water column was high, the system acted as sink for CO₂ which suggests the use of lime to prevent these systems from becoming hypereutrophic and carbon source at the same time.     

Survival and distribution of aeromonas hydrophila in near-shore coastal waters of Puerto Rico receiving rum distillery effluent

For a period of 1 year, monthly water samples were taken for estimates of Aeromonas hydrophila density at 6 sites in Ensenada de Boca Vieja near San Juan, Puerto Rico. Five sites were associated with the effluent plume of the world's largest rum distillery, the sixth site was 177 m upcurrent. Fifteen water quality parameters were monitored concurrently with A. hydrophila estimates. The toxic and stimulatory nature of the effluent made correlations with any physicochemical parameter difficult. However, a significant multiple regression was obtained against density of A. hydrophila using temperature, total phosphorus, total organic carbon and orthophosphates. Densities of A. hydrophila were always higher in the effluent plume and usually highest at the site closest to effluent outfall. Suspensions of A. hydrophila placed in diffusion chambers at the effluent point source not only survived, but gradually increased in density, while 500 m upcurrent densities of A. hydrophila in diffusion chambers rapidly declined. Significant differences in A. hydrophila density between the two sites could be detected after only 18 h. The diffusion chamber studies confirm natural correlations with water quality that indicate A. hydrophila densities in marine habitats can become elevated under the appropriate conditions. Higher densities of other potential pathogens e.g. Klebsiella pneumoniae, Vibrio cholerae, were also observed in the rum distillery effluent plume.     

Molecular subtypes of Campylobacter spp., Salmonella enterica, and Escherichia coli O157:H7 isolated from faecal and surface water samples in the Oldman River watershed, Alberta, Canada

Campylobacter spp., Salmonella enterica, and Escherichia coli O157:H7 isolated from 898 faecal, 43 sewage, and 342 surface water samples from the Oldman River were characterized using bacterial subtyping methods in order to investigate potential sources of contamination of the watershed. Among these pathogens, Campylobacter spp. were the most frequently isolated from faecal, sewage, and surface water samples (266/895, 11/43, and 91/342, respectively), followed by Salmonella (67/898, 8/43, and 29/342, respectively), and E. coli O157:H7 (16/898, 2/43, and 8/342, respectively). Salmonella Rubislaw was the most common serovar isolated from water. This serovar was also isolated from two wild bird species. Most other serovars isolated from water were either not isolated from animals or were isolated from multiple species. E. coli O157:H7 was predominantly isolated from cattle. The most common phage-types of this pathogen from cattle were also the most common among water isolates, and there were exact pulsed field gel electrophoresis and comparative genomic fingerprint matches between cattle, sewage, and water isolates. Campylobacters were commonly isolated from surface waters and faeces from most animal species. Restriction fragment length polymorphism of the Campylobacter flaA gene identified several location and host species-specific (cattle, goose, pig) fingerprints. Molecular subtyping of these bacterial pathogens shows considerable promise as a tool for determining the sources of faecal pollution of water.     

Microbial degradation of nitrilotriacetate (NTA) during river water/groundwater infiltration: Laboratory column studies

In laboratory column experiments with aquifer material collected from a natural river water/groundwater infiltration site, the effects of changes in NTA concentration (0.06–3.40 μM), temperature (5–20°C), and redox conditions on the microbial degradation of NTA during infiltration have been investigated. Under both aerobic and denitrifying conditions, NTA was rapidly mineralized and supported microbial growth as a sole carbon and energy source. The presence of other degradable organic compounds and of trace metals had no significant effect on the total rate of NTA elimination after a 21.8 cm flow distance. At concentrations between 0.02 and 0.05 μM, NTA degradation was still rapid (apparent pseudo first-order rate constants of up to 15 d⁻¹). From the results of the column experiments it may be concluded that under environmental conditions typical for Switzerland, very low residual NTA concentrations (< 0.01 μM) should be present at all times of the year in the groundwater after only a few meters of infiltration, even when concentrations of NTA in river water reach 3–4 μM. This conclusion is corroborated by results of field measurements.     

Biodegradation of 2-methylisoborneol by single bacterium in culture media and river water environment

2-Methylisoborneol (2-MIB) is a typical odorant in water sources. It is difficult for conventional water treatment to remove it. In this study, three strains capable of removing 2-MIB were isolated from activated carbon of sand filter. They were identified to be Shinella zoogloeoides, Bacillus idriensis and Chitinophagaceae bacterium based on 16S rRNA gene sequence analysis. The biodegradation of 2-MIB was improved with the presence of external carbon (glycerol, glucose, etc.). In the period of 20 days, Bacillus idriensis can remove 2 mg L^?1 2-MIB to 368.2 and 315.4 μg L^?1 in mineral salts medium without and with glycerol. Chitinophagaceae bacterium can remove it to 265.6 and 185.4 μg L^?1 without and with glucose. The enzymatic activity of B. Idriensis was lower when external carbon coexisted with 2-MIB. This indicated that a carbon source can inhibit the use of 2-MIB, but it can provide rich nutrients for the growth of bacteria.     

Speciation and variation in the occurrence of haloacetic acids in three water supply systems in England

An investigation into the speciation and occurrence of nine haloacetic acids (HAAs) was conducted during the period of April 2007 to March 2008 and involved three drinking water supply systems in England, which were chosen to represent a range of source water conditions; these were an upland surface water, a lowland surface water and a groundwater. Samples were collected seasonally from the water treatment plants and at different locations in the distribution systems. The highest HAA concentrations occurred in the upland surface water system, with an average total HAA concentration of 21.3 μg/L. The lowest HAA levels were observed in the groundwater source, with a mean concentration of 0.6 μg/L. Seasonal variations were significant in the HAA concentrations; the highest total HAA concentrations were found during the autumn, when the concentrations were approximately two times higher than in winter and spring. HAA speciation varied among the water sources, with dichloroacetic acid and trichloroacetic acid dominant in the lowland surface water system and brominated species dominant in the upland surface water system. There was a strong correlation between trihalomethanes and HAAs when considering all samples from the three systems in the same data set (r ²=0.88); however, the correlation was poor/moderate when considering each system independently.     

Qualitative and quantitative studies on the in situ adsorption, degradation and toxicity of acrylamide by the spiking of the waters of two sewage works and a river

Novel experiments which involved the dosing of acrylamide into an activated sludge sewage works, a biological filter sewage works, and a river which discharged into an estuary were performed during the period from October 1979 to July 1980. In order to assess the ability of a sewage works to degrade acrylamide, an activated sludge and a percolating biological filter plant were exposed to constant dosings of acrylamide. Little loss of acrylamide occurred in either the primary or the final settlement tanks. Approximately 50% of dosed acrylamide was lost from both the activated sludge tanks and the biological filter beds. Laboratory experiments were used to help explain the in situ results. In another study acrylamide was dosed into a stream continuously for 74 days in order to assess the initial in situ adsorption and degradation, and the possibility of initiating further in situ degradation owing to acclimatisation of microheterotrophs. Dilution effects owing to ground water infiltration and additional tributaries were allowed for by monitoring both acrylamide concentration and river flow at various stations downstream of the source of acrylamide addition. The resulting quantitative mass flow study showed that no in situ loss of acrylamide occurred for a stream retention of 4–5 h. Incubations in the laboratory of collected water samples suggested some possible increase in degradative ability of the samples which had been exposed to acrylamide. A qualitative assessment of the insect fauna before, during and after exposure to acrylamide showed a reduced species diversity to occur within 5 h when exposed to 50 μg 1⁻¹ acrylamide. Within 21 days only Hydropsyche instabilis was observed in the river. Some recolonization was noted following cessation of acrylamide dosing.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments-IV Indicators of hydrocarbon pollution for waters

The ratios between organic carbons and hydrocarbon constituents were compared for polluted river waters from the Tokyo area and unpolluted river, brook, reservoir and pond waters from the Ogasawara (Bonin) Islands to derive indicators of hydrocarbon pollution fossil fuels and their products and both combustion products, and industrial products. The hydrocarbons as carbon (HCC)/total organic carbon (TOC). HCC extractable organic carbon with ethyl acetate (EOC), squalane as carbon (SgC),TOC, SqC/EOC, and unresolved complex mixture of hydrocarbons (UCMH)n-Alkane (C₁₅-C₃₃) ratios of the waters from the Tokyo area were much higher than those of the waters from the Ogasawara Islands. The values of carbon preference index (CPI₁₁) for n-alkanes (C₁₄-C₁₄) close to unity were found in all the water samples from the Tokyo area. They are considerably lower than those of the water samples from the Ogasawara Islands. These results indicate that the HCC TOC, HCC/EOC UCMH/n-Alkane and CPI₁₁ values are the important indicators of hydrocarbon pollution. Further, it was suggested that the SqC/TOC and SqC/EOC ratios are useful indicators of urban-industrial activities on water systems.     

Associations among pathogenic bacteria, parasites, and environmental and land use factors in multiple mixed-use watersheds

Over a five year period (2004-08), 1171 surface water samples were collected from up to 24 sampling locations representing a wide range of stream orders, in a river basin in eastern Ontario, Canada. Water was analyzed for Cryptosporidium oocysts and Giardia cyst densities, the presence of Salmonella enterica subspecies enterica, Campylobacter spp., Listeria monocytogenes, and Escherichia coli O157:H7. The study objective was to explore associations among pathogen densities/occurrence and objectively defined land use, weather, hydrologic, and water quality variables using CART (Classification and Regression Tree) and binary logistical regression techniques. E. coli O157:H7 detections were infrequent, but detections were related to upstream livestock pasture density; 20% of the detections were located where cattle have access to the watercourses. The ratio of detections:non-detections for Campylobacter spp. was relatively higher (>1) when mean air temperatures were 6% below mean study period temperature values (relatively cooler periods). Cooler water temperatures, which can promote bacteria survival and represent times when land applications of manure typically occur (spring and fall), may have promoted increased frequency of Campylobacter spp. Fifty-nine percent of all Salmonella spp. detections occurred when river discharge on a branch of the river system of Shreve stream order = 9550 was >83 percentile. Hydrological events that promote off farm/off field/in stream transport must manifest themselves in order for detection of Salmonella spp. to occur in surface water in this region. Fifty seven percent of L. monocytogenes detections occurred in spring, relative to other seasons. It was speculated that a combination of winter livestock housing, silage feeding during winter, and spring application of manure that accrued during winter, contributed to elevated occurrences of this pathogen in spring. Cryptosporidium and Giardia oocyst and cyst densities were, overall, positively associated with surface water discharge, and negatively associated with air/water temperature during spring-summer-fall. Yet, some of the highest Cryptosporidium oocyst densities were associated with low discharge conditions on smaller order streams, suggesting wildlife as a contributing fecal source. Fifty six percent of all detections of ≥2 bacteria pathogens (including Campylobacter spp., Salmonella spp., and E. coli O157:H7) in water was associated with lower water temperatures (<∼14 °C; primarily spring and fall) and when total rainfall the week prior to sampling was >∼27 mm (62 percentile). During higher water temperatures (>∼14 °C), a higher amount of weekly rainfall was necessary to promote detection of ≥2 pathogens (primarily summer; weekly rainfall ∼>42 mm (>77 percentile); 15% of all ≥2 detections). Less rainfall may have been necessary to mobilize pathogens from adjacent land, and/or in stream sediments, during cooler water conditions; as these are times when manures are applied to fields in the area, and soil water contents and water table depths are relatively higher. Season, stream order, turbidity, mean daily temperature, surface water discharge, cropland coverage, and nearest upstream distance to a barn and pasture were variables that were relatively strong and recurrent with regard to discriminating pathogen presence and absence, and parasite densities in surface water in the region.     

Integrated analysis of water quality parameters for cost-effective faecal pollution management in river catchments

In many parts of the world, microbial contamination of surface waters used for drinking, recreation, and shellfishery remains a pervasive risk to human health, especially in Less Economically Developed Countries (LEDC). However, the capacity to provide effective management strategies to break the waterborne route to human infection is often thwarted by our inability to identify the source of microbial contamination. Microbial Source Tracking (MST) has potential to improve water quality management in complex river catchments that are either routinely, or intermittently contaminated by faecal material from one or more sources, by attributing faecal loads to their human or non-human sources, and thereby supporting more rational approaches to microbial risk assessment. The River Ouse catchment in southeast England (U.K.) was used as a model with which to investigate the integration and application of a novel and simple MST approach to monitor microbial water quality over one calendar year, thereby encompassing a range of meteorological conditions. A key objective of the work was to develop simple low-cost protocols that could be easily replicated. Bacteriophages (viruses) capable of infecting a human specific strain of Bacteroides GB-124, and their correlation with presumptive Escherichia coli, were used to distinguish sources of faecal pollution. The results reported here suggest that in this river catchment the principal source of faecal pollution in most instances was non-human in origin. During storm events, presumptive E. coli and presumptive intestinal enterococci levels were 1.1-1.2 logs higher than during dry weather conditions, and levels of the faecal indicator organisms (FIOs) were closely associated with increased turbidity levels (presumptive E. coli and turbidity, r = 0.43). Spatio-temporal variation in microbial water quality parameters was accounted for by three principal components (67.6%). Cluster Analysis, reduced the fourteen monitoring sites to six representative ‘sentinel’ sites. The correlation coefficient between presumptive E. coli and phages of Bacteroides GB-124 was very small (r = 0.05) whilst that between turbidity and suspended solids was high (r = 0.62). Variations in climate, animal and anthropogenic interferences were all, either directly or indirectly, related to faecal contamination. The findings show the importance of meteorological conditions, such as storm events, on microbial water quality, and suggest that any future increases in the frequency of storm events (associated with climate change) are likely to result in a greater incidence of FIO/pathogen loads. This low-cost approach could help to predict spatio-temporal ‘hotspots’ of elevated waterborne disease risk. The work also represents an important step towards integrating novel MST tools into river catchment modelling.