Physicochemical Factors Influence the Abundance and Culturability of Human Enteric Pathogens and Fecal Indicator Organisms in Estuarine Water and Sediment.

To assess fecal pollution in coastal waters, current monitoring is reliant on culture-based enumeration of bacterial indicators, which does not account for the presence of viable but non-culturable or sediment-associated micro-organisms, preventing effective quantitative microbial risk assessment (QMRA). Seasonal variability in viable but non-culturable or sediment-associated bacteria challenge the use of fecal indicator organisms (FIOs) for water monitoring. We evaluated seasonal changes in FIOs and human enteric pathogen abundance in water and sediments from the Ribble and Conwy estuaries in the UK. Sediments possessed greater bacterial abundance than the overlying water column, however, key pathogenic species (Shigella spp., Campylobacter jejuni, Salmonella spp., hepatitis A virus, hepatitis E virus and norovirus GI and GII) were not detected in sediments. Salmonella was detected in low levels in the Conwy water in spring/summer and norovirus GII was detected in the Ribble water in winter. The abundance of E. coli and Enterococcus spp. quantified by culture-based methods, rarely matched the abundance of these species when measured by qPCR. The discrepancy between these methods was greatest in winter at both estuaries, due to low CFU's, coupled with higher gene copies (GC). Temperature accounted for 60% the variability in bacterial abundance in water in autumn, whilst in winter salinity explained 15% of the variance. Relationships between bacterial indicators/pathogens and physicochemical variables were inconsistent in sediments, no single indicator adequately described occurrence of all bacterial indicators/pathogens. However, important variables included grain size, porosity, clay content and concentrations of Zn, K, and Al. Sediments with greater organic matter content and lower porosity harbored a greater proportion of non-culturable bacteria (including dead cells and extracellular DNA) in winter. Here, we show the link between physicochemical variables and season which govern culturability of human enteric pathogens and FIOs. Therefore, knowledge of these factors is critical for accurate microbial risk assessment. Future water quality management strategies could be improved through monitoring sediment-associated bacteria and non-culturable bacteria. This could facilitate source apportionment of human enteric pathogens and FIOs and direct remedial action to improve water quality.

Abundance and Distribution of Enteric Bacteria and Viruses in Coastal and Estuarine Sediments-a Review.

The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically <10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and viruses into the water column during sediment resuspension also represents a risk to water quality. In conclusion, our poor process level understanding of viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments.

Source apportionment of trace contaminants in urban sewer catchments.

Sampling and analysis of Water Framework Directive priority chemicals were undertaken in nine urban catchments across the UK. Over 9000 samples were collected from a number of different catchment sources including tap water, domestic waste water, surface water runoff, trade discharges, town centre and light industrial estate wastewaters. Determinands included trace metals, polyaromatic hydrocarbons (PAHs), persistent organic pollutants and a number of common pharmaceuticals. Loads of the chemicals from each catchment entering the local wastewater treatment works (WwTW) were estimated and were shown to be relatively consistent between different catchments, after taking population into account. A Monte Carlo mixing model was used to combine the concentrations and flows from the different catchment sources and to predict concentrations and loads entering the WwTW. Based on the model output, the significance of the different sources could be evaluated. The study highlighted the importance of domestic wastewater as a source of contaminants, including metals and trace organic substances (such as ethylenediaminetetraacetic acid (EDTA), bisphenol A, nonylphenol and tributyl tin (TBT)). Concentrations in trade discharges were important in some locations in the case of nonylphenol, EDTA, TBT, as well as for some metals such as copper, zinc and nickel. Contributions to the total load from town centre and light industrial estate sources were generally less than 10% of the total.

Concentrations of trace substances in sewage sludge from 28 wastewater treatment works in the UK.

Concentrations of trace substances in sewage sludge have been measured in a survey of 28 wastewater treatment works (WwTWs) in the UK carried out over a period of 12months. Approximately 250 samples were analysed for more than 40 trace contaminants, including trace metals, pharmaceuticals, polycyclic aromatic hydrocarbons (PAHs), 'emerging' and regulated organic pollutants. All substances investigated were found to be present in at least some of the sludges sampled. Concentrations were relatively homogenous across all the WwTWs, irrespective of the treatment process, influent and effluent concentrations, and the location of the sludge sampling point within each works. Analysis of the results against existing regulatory and proposed thresholds suggested that levels are mostly below the limits set in the Sewage Sludge Directive, and proposed new limits for sludge used in agriculture. Predicted soil concentrations after application of sewage sludge to land were below the predicted no effect concentrations (PNEC) for all determinands. Predicted concentrations of pharmaceuticals in soil were also below thresholds deemed to indicate negligible environmental risk.

Performance of UK wastewater treatment works with respect to trace contaminants.

This study examined the performance of 16 wastewater treatment works to provide an overview of trace substance removal in relation to meeting the objectives of the Water Framework Directive (WFD). Collection and analysis of over 2400 samples including sewage influent, process samples at different stages in the treatment process and final effluent has provided data on the performance of current wastewater treatment processes and made it possible to evaluate the need for improved effluent quality. Results for 55 substances, including metals, industrial chemicals and pharmaceuticals are reported. Data for sanitary parameters are also provided. A wide range of removal efficiencies was observed. Removal was not clearly related to the generic process type, indicating that other operational factors tend to be important. Nonetheless, removals for many substances of current concern were high. Despite this, current proposals for stringent water quality standards mean that further improvements in effluent quality are likely to be required.

A comparison of lidocaine versus normal saline for local anesthesia before intravenous cannula insertion.

A number of studies have found that one of the leading causes of patient dissatisfaction with nursing care is directly related to the pain associated with the method of IV (intravenous) cannulation. The purpose of this study was to identify which solution, lidocaine hydrochloride 1% (LIDO), normal saline with preservatives (NSP), or normal saline without preservatives (NS), would have the best local anesthetic effect, as reported by patients, for venous cannulation. The research design was a randomized, double-blind study that compared three solutions for their anesthetic effect during initiation of peripheral IV catheters. The sample consisted of 60 (N=60) patients. The setting was in the radiology outpatient department. The Wong-Baker FACES Pain Rating Scale was used to measure the amount of pain. Data analysis was completed using the Analysis of Variance (ANOVA) and post hoc Scheffé test (Post-Hoc ANOVA). Findings from this study indicated that LIDO and NSP provided equal anesthetic effects.