A sea change ahead for recreational water quality criteria

The reported fate of Escherichia coli in the environment ranges from extended persistence to rapid decline. Incomplete understanding of factors that influence survival hinders risk assessment and modeling of the fate of fecal indicator bacteria (FIB) and pathogens. FIB persistence in subtropical aquatic environments was explored in outdoor mesocosms inoculated with five E. coli strains. The manipulated environmental factors were (i) presence or absence of indigenous microbiota (attained by natural, disinfected, and cycloheximide treatments), (ii) freshwater versus seawater, and (iii) water column versus sediment matrices. When indigenous microbes were removed (disinfected), E. coli concentrations decreased little despite exposure to sunlight. Conversely, under conditions that included the indigenous microbiota (natural), significantly greater declines in E. coli occurred regardless of the habitat. The presence of indigenous microbiota and matrix significantly influenced E. coli decline, but their relative importance differed in freshwater versus seawater. Cycloheximide, which inhibits protein synthesis in eukaryotes, significantly diminished the magnitude of E. coli decline in water but not in sediments. The inactivation of protozoa and bacterial competitors (disinfected) caused a greater decline in E. coli than cycloheximide alone in water and sediments. These results indicate that the autochthonous microbiota are an important contributor to the decline of E. coli in fresh and seawater subtropical systems, but their relative contribution is habitat dependent. This work advances our understanding of how interactions with autochthonous microbiota influence the fate of E. coli in aquatic environments and provides the framework for studies of the ecology of enteric pathogens and other allochthonous bacteria in similar environments.T he sanitary quality of recreational waters in Florida and across the United States is currently assessed by enumeration of fecal indicator bacteria (FIB) (i.e., fecal coliforms, Escherichia coli, and enterococci), which are also intended to act as pathogen surrogates (1, 2). The validity of this paradigm is the subject of ongoing debate, and it is argued that the current regulatory standards do not adequately protect human health, due mainly to the differences in survival and transport characteristics between the FIB and pathogens (3-9). When the assumed predictive relationship is absent (e.g., FIB not detected but pathogens present), public health may be threatened by exposure of humans to pathogens. On the other hand, FIB that are detected in the absence of pathogens can lead to unnecessary beach and shellfishing area closures, which can pose economic hardships in coastal communities.While the roles of sediments and aquatic vegetation as a refuge and a potential reservoir of FIB are the subjects of many studies (10-16), the relative influence of indigenous microbiota on the persistence and rate of decline of FIB in aquatic environments is less well characterized. Germicidal sunlight r...

Section: Discussionmentioning

confidence: 99%

Indigenous Microbiota and Habitat Influence Escherichia coli Survival More than Sunlight in Simulated Aquatic Environments

Korajkic

Wanjugi

Harwood

2013

“…Additional studies conducted in a subtropical environment, such as that of South Florida, where this study was conducted, have repeatedly shown the limited accuracy of indicator microbe standards for determining the presence of pathogens (27,35). This lack of correlation is understandable since an indicator microbe, such as enterococci, may come from relatively low-risk sources of fecal pollution and therefore may not be related to human or other high-risk sources of fecal pollution and pathogens (9). It has also been shown in both subtropical and temperate climates that indicator bacteria can multiply in the environment, resulting in a false impression of increased microbial pollution and pathogen presence (4,7,19,24,41,45,57,58).…”

mentioning

confidence: 90%

Presence of Pathogens and Indicator Microbes at a Non-Point Source Subtropical Recreational Marine Beach

Abdelzaher

Wright

Ortega

et al. 2010

Self Cite

164

143

Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.Global estimates indicate that each year more than 120 million cases of gastrointestinal disease and 50 million cases of severe respiratory diseases are caused by swimming and bathing in wastewater-polluted coastal waters (42). Swimming-related illness is attributed predominantly to exposure to microbial pathogens, which enter the water through point sources, such as sewage outfalls. Water quality at beaches may also be impacted by non-point sources, such as storm water runoff, sand resuspension, animal fecal inputs, and human bather shedding (8,12,22,47,59).The concentration of indicator microorganisms in a body of recreational water is used to estimate the health risk to bathers. These microbes serve as surrogates for microbial pathogens. Studies show that the U.S. Environmental Protection Agency (EPA)-recommended indicator microbe for marine beaches, enterococci, shows a significant correlation with illness in marine beaches impacted by point source pollution (38,54). However, a similar correlation has not been identifi...

“…aterborne pathogens pose a health risk to recreational water users (1), in drinking water systems (2), and in aquatic organisms such as shellfish that are consumed by humans (3). These waterborne pathogens include more than 40 different groups or genera, including viruses, bacteria, protozoa, cyanobacteria, and helminths (4).…”

mentioning

confidence: 99%

Ultrafiltration and Microarray for Detection of Microbial Source Tracking Marker and Pathogen Genes in Riverine and Marine Systems

Harwood

Weidhaas

2016

Pathogen identification and microbial source tracking (MST) to identify sources of fecal pollution improve evaluation of water quality. They contribute to improved assessment of human health risks and remediation of pollution sources. An MST microarray was used to simultaneously detect genes for multiple pathogens and indicators of fecal pollution in freshwater, marine water, sewage-contaminated freshwater and marine water, and treated wastewater. Dead-end ultrafiltration (DEUF) was used to concentrate organisms from water samples, yielding a recovery efficiency of >95% for Escherichia coli and human polyomavirus. Whole-genome amplification (WGA) increased gene copies from ultrafiltered samples and increased the sensitivity of the microarray. Viruses (adenovirus, bocavirus, hepatitis A virus, and human polyomaviruses) were detected in sewage-contaminated samples. Pathogens such as Legionella pneumophila, Shigella flexneri, and Campylobacter fetus were detected along with genes conferring resistance to aminoglycosides, beta-lactams, and tetracycline. Nonmetric dimensional analysis of MST marker genes grouped sewage-spiked freshwater and marine samples with sewage and apart from other fecal sources. The sensitivity (percent true positives) of the microarray probes for gene targets anticipated in sewage was 51 to 57% and was lower than the specificity (percent true negatives; 79 to 81%). A linear relationship between gene copies determined by quantitative PCR and microarray fluorescence was found, indicating the semiquantitative nature of the MST microarray. These results indicate that ultrafiltration coupled with WGA provides sufficient nucleic acids for detection of viruses, bacteria, protozoa, and antibiotic resistance genes by the microarray in applications ranging from beach monitoring to risk assessment. W aterborne pathogens pose a health risk to recreational water users (1), in drinking water systems (2), and in aquatic organisms such as shellfish that are consumed by humans (3). These waterborne pathogens include more than 40 different groups or genera, including viruses, bacteria, protozoa, cyanobacteria, and helminths (4). Additional waterborne pathogens will doubtless emerge over time due to increased proportions of sensitive populations, globalization of commerce, microbial evolution, and use of reclaimed water as drinking water (5). Many waterborne pathogens originate from fecal pollution in storm water runoff from agricultural and urban surfaces (6) or direct release of untreated sewage to surface water (7). Additional sources of waterborne fecal pathogens include wildlife and domesticated animals such as deer, dogs, raccoons, cats, and wild avian species (8). Still other waterborne pathogens, such as Vibrio spp., are autochthonous to aquatic environments (9).The microbiological safety of surface water has been assessed for over a century by enumeration of fecal indicator bacteria (FIB) (10). Other monitoring techniques such as microbial source tracking (MST) are advantageous compared to enumeration ...