Bacterial Indicator Organisms Research Articles

Comparison of Three Air Sampling Methods for the Quantification of Salmonella, Shiga-toxigenic Escherichia coli (STEC), Coliforms, and Generic E. coli from Bioaerosols of Cattle and Poultry Farms

Recent fresh produce outbreaks potentially associated with bioaerosol contamination from animal operations in adjacent land highlighted the need for further study to better understand the associated risk. The purpose of this research was to evaluate three sampling methods for quantifying target bacterial bioaerosols from animal operations. A dairy cattle and poultry farm located in Georgia, U.S. were visited six times each. Air was collected for 10 min using: 2-stage Andersen impactor with and without mineral oil overlay and impingement samplers. Sampling devices were run concurrently at 0.1, 1, and 2 m heights (n = 36). Andersen samplers were loaded with CHROMagar™ Salmonella, CHROMagar™ STEC, or Brilliance™ coliforms/E. coli. The impingement sampler contained buffered peptone water (20 mL) which was vacuum filtered through a 0.45 µm filter and placed onto the respective media. Plates were incubated at 37 ℃ for 48 h. PCR confirmation followed targeting ttr for Salmonella and stx1, stx2, and eae genes for STEC. No significant differences were found among methods to quantify coliforms and E. coli. Salmonella and STEC bioaerosols were not detected by any of the methods (Limit of detection: 0.55 log CFU/m3). E. coli bioaerosols were significantly greater in the poultry (2.76–5.00 log CFU/m3) than in the cattle farm (0.55–2.82 log CFU/m3) (p < 0.05), and similarly distributed at both stages in the Andersen sampler (stage 1:>7 μm; stage 2: 0.65–7 μm particle size). Sampling day did not have a significant effect on the recovery of coliforms/E. coli bioaerosols in the poultry farm when samples were taken at the broiler house exhaust fan (p > 0.05). A greater and constant emission of coliforms and E. coli bioaerosols from the poultry farm warrants further investigation. These data will help inform bioaerosol sampling techniques which can be used for the quantification of bacterial foodborne pathogens and indicator organisms for future research.

Microbial water quality investigation through flow cytometry fingerprinting: from source to tap

Abstract Ensuring the quality of treated drinking water is crucial for preventing potential health impacts, regulatory fines, and reputation damage. Traditional culture-based microbiological methods often fail to capture the heterogeneity of the bacterial communities in drinking water. This study employed daily interstage monitoring and flow cytometry (FCM) analysis over a period of one year to investigate the dynamics of water treatment processes and service reservoirs. The objective of this study was to test the utility of FCM fingerprints for aiding in microbial event detection. We found that the chlorine concentration contact time was pivotal for microbial log reduction across the treatment works. FCM fingerprints exhibited significant deviations during operational events, such as process interruptions, but did not correlate with the presence of bacterial indicator organisms in the distributed and tap water. Furthermore, the diversity of bacterial fingerprints, quantified by the Bray–Curtis dissimilarity index, served as an indicator for identifying potentially poor microbial water quality. In chlorinated waters with low cell counts, the background signal shows potential as a metric to differentiate between different water sources, thereby offering the possibility to characterize breakthrough events in these circumstances that challenge most other microbial analytical methods. Interestingly, groundwater from simpler treatment works showed a higher occurrence of bacterial indicators, whereas surface water works had a lower incidence. These findings underpin the importance of appropriate disinfection even for “low-risk” source waters and the added value that the statistical interpretation of FCM data can offer objective decision making.

Development of a Simple and Effective Water Disinfection System Using an Electrochemical Mixed Oxidants-Generating System to Remove Waterborne Pathogens in Developing Countries

Despite tremendous efforts from various international agencies such as World Health Organization (WHO), waterborne diseases are a still major cause of morbidity and mortality in the world – with more than 1 billion incidences and more than 2 million deaths per year. As an effort to mitigate this global burden, we developed a water disinfection system using electrochemical mixed oxidants-generating system. This system is simple, inexpensive, and easy to use. In this study, we determined the effectiveness of the new water disinfection system against waterborne pathogens using &lt;i&gt;Escherichia coli&lt;/i&gt; CN13, bacteriophage MS2 and &lt;i&gt;Bacillus subtilis&lt;/i&gt; spores as bacterial, viral, and protozoa indicator organisms, respectively. The results of this study showed that the new water disinfection system is very effective against &lt;i&gt;E. coli&lt;/i&gt; CN13 (~3 log&lt;sub&gt;10&lt;/sub&gt; inactivation within 3 minutes with 0.3 mg/L of free chlorine) and coliphage MS2 (&gt; 4 log&lt;sub&gt;10&lt;/sub&gt; inactivation within 3 minutes with 0.5 mg/L of free chlorine) Although the inactivation of &lt;i&gt;B. subtilis&lt;/i&gt; spores by the new disinfection system was somewhat slow (~0.5 log&lt;sub&gt;10&lt;/sub&gt; inactivation in 60 minutes with 10 mg/L of free chlorine), the result is similar to previous studies with free chlorine. Overall, the results of this study indicate that the new water disinfection system using an electrochemical mixed oxidants-generating system is easy to use, convenient to carry, and also very effective against most waterborne pathogens, so it could be a sustainable solution for providing safe drinking water to the people in developing countries.

Efficacy of single pass UVC air treatment for the inactivation of coronavirus, MS2 coliphage and Staphylococcus aureus bioaerosols

There is strong evidence that SARS-CoV-2 is spread predominantly by airborne transmission, with high viral loads released into the air as respiratory droplets and aerosols from the infected subject. The spread and persistence of SARS-CoV-2 in diverse indoor environments reinforces the urgent need to supplement distancing and PPE based approaches with effective engineering measures for microbial decontamination – thereby addressing the significant risk posed by aerosols. We hypothesized that a portable, single-pass UVC air treatment device (air flow 1254 L/min) could effectively inactivate bioaerosols containing bacterial and viral indicator organisms, and coronavirus without reliance on filtration technology, at reasonable scale. Robust experiments demonstrated UVC dose dependent inactivation of Staphylococcus aureus (UV rate constant (k) = 0.098 m2/J) and bacteriophage MS2, with up to 6-log MS2 reduction achieved in a single pass through the system (k = 0.119 m2/J). The inclusion of a PTFE diffuse reflector increased the effective UVC dose by up to 34% in comparison to a standard Al foil reflector (with identical lamp output), resulting in significant additional pathogen inactivation (1-log S. aureus and MS2, p < 0.001). Complete inactivation of bovine coronavirus bioaerosols was demonstrated through tissue culture infectivity (2.4-log reduction) and RT-qPCR analysis – confirming single pass UVC treatment to effectively deactivate coronavirus to the limit of detection of the culture-based method. Scenario-based modelling was used to investigate the reduction in risk of airborne person-to-person transmission based upon a single infected subject within the small room. Use of the system providing 5 air changes per hour was shown to significantly reduce airborne viral load and maintain low numbers of RNA copies when the infected subject remained in the room, reducing the risk of airborne pathogen transmission to other room users. We conclude that the application of single-pass UVC systems (without reliance on HEPA filtration) could play a critical role in reducing the risk of airborne pathogen transfer, including SARS-CoV2, in locations where adequate fresh air ventilation cannot be implemented.

Milk Product Safety and Household Food Hygiene Influence Bacterial Contamination of Infant Food in Peri-Urban Kenya.

BackgroundMilk is a common infant food in peri-urban Kenya that can transmit diarrhea-causing enteric pathogens. Little is known about how contamination of milk at point of purchase and household handling of milk-based infant foods contribute to infant exposure to enteric pathogens.ObjectiveTo compare the prevalence and concentrations of bacterial indicator organisms and enteric pathogens in unpackaged, fresh pasteurized, and ultra-high temperature (UHT) treated milk at purchase and assess the influence of the type of milk used to prepare infant food on contamination of this food.MethodsPaired samples of purchased milk and infant food prepared with this milk were obtained from 188 households in low-income neighborhoods in Kisumu, Kenya. Samples were cultured on selective media to isolate Salmonella enterica, Shigella spp., Klebsiella aerogenes, Proteus spp., and Escherichia coli, with pathogens validated by PCR. Probability of detection of these bacteria was compared by milk product treatment and packaging method, and between milk at point of purchase vs. food at point of infant consumption.ResultsUnpackaged milk was most contaminated at point of purchase, but bacterial contamination was also present in pasteurized and UHT milk at purchase. Presence of bacteria in UHT and fresh pasteurized milk at purchase predicted presence of the same bacteria type in infant food. Prevalence of bacterial contamination and concentration level for bacterial indicators generally increased between point of purchase and consumption in UHT and fresh pasteurized milk-based food but decreased in unpackaged milk-based food. Prevalence of the four fecal bacteria were similar in infant foods prepared with each type of milk.ConclusionBoth pre-market contamination and post-purchase handling influence the likelihood of infants ingesting foods contaminated by diarrheal pathogens.

Are carbon water filters safe for private wells? Evaluating the occurrence of microbial indicator organisms in private well water treated by point-of-use activated carbon block filters.

Point-of-use (POU) water treatment is highly relevant to private well users vulnerable to chemical contamination, but uncertainty remains around the effects of activated carbon based POU devices on the microbial quality of the treated water. In this study, under-sink activated carbon block water filters were installed in 17 homes relying on private well water in North Carolina. The influent and effluent water in each home was evaluated for bacterial and viral microbial indicator organisms monthly for five months. Multiple logistic regression was used to identify water quality and water usage variables that were significant predictors of each indicator organism occurring in the filter effluent. The odds of total coliforms occurring in the effluent decreased by 84% with each 1-log10 increase in the influent HPC (p<0.05), suggesting a protective effect by native heterotrophic bacteria, but increased by over 50 times with low cumulative water use (p<0.05). The filters were not protective against coliphages in the influent and viral shedding may occur after periods of increased virus concentrations in the raw well water. Specific bacteria were also found to increase in the effluent, causing a shift in the bacterial community composition, although potential opportunistic pathogens were detected in both the influent and the effluent. Overall, under normal conditions of use, the filters tested in this study did not represent a significant additional risk for well users beyond the existing exposures from undisinfected well water alone.

A mechanistic model for estimating bacteria levels in stormwater ponds

This paper presents a three-dimensional CFD based hydro-environmental model that simulates fate and transport of bacteria in water bodies. The model numerically solves unsteady incompressible Reynolds-Averaged Navier-Stokes equations on a structured grid. Free-floating and particle-attached bacteria were modelled separately regarding both fate and transport. Therefore, a sediment transport model was integrated into the main model in order to model particle-attached bacteria transport. In addition, Volume of Fluid approach was implemented to capture the water surface movements. Wind effect was also considered in the modelling using shear stress on the water surface. Since stormwater reuse is the source of some public health concerns, a stormwater pond was chosen as the test case for the model. The model was applied to simulate the distribution of bacterial indicator organisms in the Inverness Stormwater Pond in Calgary, Alberta, which is a large T-shaped pond with several inlets and outlets. The bacteria distribution in the pond was simulated for three rain events that occurred in the area. In six locations of the pond the modelled bacteria distribution was compared to collected data using non-dimensional bacteria concentrations. The comparison showed good agreement and indicated that the middle of the pond, close to the surface had the lowest levels of bacteria and thus, was considered the optimal location for withdrawal for reusing pond water. Furthermore, planting a tree barrier on the north bank of the West wing of the pond was shown to mitigate bacteria transport away from the inlets into the pond body and substantially decrease the risk of contamination at the optimal water withdrawal location.

Microbiological Quality of Cooked Chicken: Results of Monitoring in England (2013 to 2017)

Results from monitoring of the microbiological quality of 2,721 samples of ready-to-eat cooked chicken collected between 2013 to 2017 in England were reviewed: 70% of samples were from retail, catering or manufacture and 30% were imported and collected at English ports. Samples were tested for a range of bacterial pathogens and indicator organisms. Six samples (<1%) had unsatisfactory levels of pathogens which were potentially injurious to health. Neither Salmonella nor Campylobacter were recovered from any sample. Two samples from catering settings contained either an unsatisfactory level of Bacillus cereus (5 x 10 6 CFU/g) or an unsatisfactory level of coagulase positive staphylococci (1.6 x 10 4 CFU/g). Listeria monocytogenes was recovered from 36 samples (one at manufacture, 26 at catering and nine at retail) and in four instances, unsatisfactory levels (≥10 2 CFU/g) were detected (three samples collected at catering and one at retail). For L. monocytogenes there were no significant differences between the rates of contamination with between the samples collected from ports, manufacture, retail supermarkets and other retailers (p = 0.288). There were no differences between the rates of contamination for other potential pathogens detected between samples from different settings. The prevalence of hygiene indicators ( Escherichia coli , Enterobacteriaceae and Aerobic Colony Counts) at import was significantly lower than in samples collected from manufacturers, retail or catering (p < 0.01). Samples collected from catering gave poorer results than all other settings. Regardless of the stage in the food chain, samples from Thailand and from other non-EU countries were of significantly better microbiological quality with respect to indicator organisms than those from the UK or from other EU countries (p = <0.001).

Removal of bacterial and viral indicator organisms in full-scale aerobic granular sludge and conventional activated sludge systems

The aim of this study was to evaluate the effectiveness of the novel aerobic granular sludge (AGS) wastewater treatment technology in removing faecal indicator organisms (FIOs) compared to the conventional activated sludge (CAS) treatment system. The work was carried out at two full-scale wastewater treatment plants (WWTP) in the Netherlands, Vroomshoop and Garmerwolde. Both treatment plants have a CAS and AGS system operated in parallel. The parallel treatment lines are provided with the same influent wastewater. The concentrations of the measured FIOs in the influent of the two WWTPs were comparable with reported literature values as follows: F-specific RNA bacteriophages at 106 PFU/100 mL, and Escherichia coli (E. coli), Enterococci, and Thermotolerant coliforms (TtC) at 105 to 106 CFU/100 mL. Although both systems (CAS and AGS) are different in terms of design, operation, and microbial community, both systems showed similar FIOs removal efficiency. At the Vroomshoop WWTP, Log10 removals for F-specific RNA bacteriophages of 1.4 ± 0.5 and 1.3 ± 0.6 were obtained for the AGS and CAS systems, while at the Garmerwolde WWTP, Log10 removals for F-specific RNA bacteriophages of 1.9 ± 0.7 and 2.1 ± 0.7 were found for the AGS and CAS systems. Correspondingly, E. coli, Enterococci, and TtC Log10 removals of 1.7 ± 0.7 and 1.1 ± 0.7 were achieved for the AGS and CAS systems at Vroomshoop WWTP. For Garmerwolde WWTP Log10 removals of 2.3 ± 0.8 and 1.9 ± 0.7 for the AGS and CAS systems were found, respectively. The measured difference in removal rates between the plants was not significant. Physicochemical water quality parameters, such as the concentrations of organic matter, nutrients, and total suspended solids (TSS) were also determined. Overall, it was not possible to establish a direct correlation between the physicochemical parameters and the removal of FIOs for any of the treatment systems (CAS and AGS). Only the removal of TSS could be positively correlated to the E. coli removal for the AGS technology at the evaluated WWTPs.

Human Bacteroides and total coliforms as indicators of recent combined sewer overflows and rain events in urban creeks

Combined sewer overflows (CSOs) are a known source of human fecal pollution and human pathogens in urban water bodies, which may present a significant public health threat. To monitor human fecal contamination in water, bacterial fecal indicator organisms (FIOs) are traditionally used. However, because FIOs are not specific to human sources and do not correlate with human pathogens, alternative fecal indicators detected using qPCR are becoming of interest to policymakers. For this reason, this study measured correlations between the number and duration of CSOs and mm of rainfall, concentrations of traditional FIOs and alternative indicators, and the presence of human pathogens in two urban creeks. Samples were collected May–July 2016 and analyzed for concentrations of FIOs (total coliforms and E. coli) using membrane filtration as well as for three alternative fecal indicators (human Bacteroides HF183 marker, human polyomavirus (HPoV), pepper mild mottle virus (PMMoV)) and nine human pathogens using qPCR. Four of the nine pathogens analyzed were detected at these sites including adenovirus, Enterohemorrhagic E. coli, norovirus, and Salmonella. Among all indicators studied, human Bacteroides and total coliforms were significantly correlated with recent CSO and rainfall events, while E. coli, PMMoV, and HPoV did not show consistent significant correlations. Further, human Bacteroides were a more specific indicator, while total coliforms were a more sensitive indicator of CSO and rainfall events. Results may have implications for the use and interpretation of these indicators in future policy or monitoring programs.

Removal of nutrients, trace organic contaminants, and bacterial indicator organisms in a demonstration-scale unit process open-water treatment wetland

A demonstration-scale unit process open-water wetland system was built to treat water from an effluent-dominated river (i.e., a river in which the flow consisted almost entirely of municipal wastewater effluent from May to October). Monitoring of the system over a two-year period indicated effective removal of nitrate, with concentrations decreasing by over 90% during summer. The temperature-independent areal first-order nitrate removal rate constant, k20, ranged from 61.7 to 68.1myr−1 after the microbial community was established, which is significantly higher than values typically observed in full-scale surface flow wetlands. The beta-adrenergic blockers, atenolol and propranolol, as well as the antiviral drug, acyclovir, were removed by photolysis and biotransformation in the wetland biomat, whereas the antiepileptic drug, carbamazepine, exhibited little removal. The bacterial indicators E. coli and enterococci decreased substantially during summer, mainly through sunlight exposure. Models of contaminant removal based upon measured flow rates and performance data collected at a similar pilot-scale system agreed well with measured data for nitrate and the trace organic contaminants. The model accurately predicted removal of enterococci but systematically over-predicted the removal of E. coli. During the two-year study period, routine maintenance was necessary to prevent colonization of the water surface with duckweed (Lemna spp.). Unit process open-water (UPOW) wetlands may offer a low-cost means of improving water quality in natural treatment systems that can be integrated with conventional surface-flow wetlands and other managed natural systems. The quantitative models of contaminant removal described in this study can be used to design natural treatment systems that balance the needs for local water quality requirements, available land and site-specific requirements.

Environmental Damage Caused by Wastewater Discharge into the Lake Manzala in Egypt

Lake Manzala is a brackish lake in northeastern Egypt on the Nile Delta. It is the largest of the northern Delta lakes of Egypt. The Lake is exposed to high inputs of pollutants from industrial, domestic, and agricultural sources. Climate gases and large amounts of particulate matter, nutrients, bacteria, heavy metals, and toxic organics are transported to the Lake through the wastewater discharge. Water samples were collected and subjected to physicochemical analysis and microbiological study. Results have shown great changes in physical and chemical properties of water including: temperature (13.5°C in winter -32°C in summer), pH (7.8-9.2), dissolved oxygen (2.5-12.8 mgl-1), total dissolved solids (1033-43406 mgl-1), total suspended solids (120-387 mgl-1), ammonia (2.5-32.3 mgl-1), nitrite (0-0.076 mgl-1), nitrate (0.01-7.88 mgl-1), phosphate (0.26-2.37 mgl-1), Fe (0.01-0.63 mgl-1), Zn (0-0.35 mgl-1), Cu (0.01-0.91 mgl-1), Cn (0.002-0.029 mgl-1) and Ni (0-0.002 mgl-1). Results, also, showed a quit great density of total viable bacterial count and indicator organisms including total Coli forms, fecal coli forms, Aeromonas spp., Staphylococcus spp. and Vibrio spp. It is concluded that water in Lake Manzala is highly damaged and the phenomena need more attention in order to reduce the pollution load that reaches the Mediterranean Sea.

Global occurrence of Torque teno virus in water systems.

Bacterial indicator organisms are used globally to assess the microbiological safety of waters. However, waterborne viral outbreaks have occurred in drinking water systems despite negative bacterial results. Using viral markers may therefore provide more accurate health risk assessment data. In this study, fecal, wastewater, stormwater, surface water (fresh and salt), groundwater, and drinking water samples were analyzed for the presence or concentration of traditional indicators, innovative indicators and viral markers. Samples were obtained in the United States, Italy, and Australia and results compared to those reported for studies conducted in Asia and South America as well. Indicators included total coliforms, Escherichia coli, enterococci, male-specific coliphages, somatic coliphages and microviradae. Viral markers included adenovirus, polyomavirus, and a potential new surrogate, Torque teno virus (TTV). TTV was more frequently found in wastewaters (38-100%) and waters influenced by waste discharges (25%) than in surface waters used as drinking water sources (5%). TTV was also specific to human rather than animal feces. While TTV numbers were strongly correlated to other viral markers in wastewaters, suggesting its utility as a fecal contamination marker, data limitations and TTV presence in treated drinking waters demonstrates that additional research is needed on this potential viral indicator.

Thermal treatment for pathogen inactivation as a risk mitigation strategy for safe recycling of organic waste in agriculture

Thermal treatment at temperatures between 46.0°C and 55.0°C was evaluated as a method for sanitization of organic waste, a temperature interval less commonly investigated but important in connection with biological treatment processes. Samples of dairy cow feces inoculated with Salmonella Senftenberg W775, Enterococcus faecalis, bacteriophage ϕX174, and porcine parvovirus (PPV) were thermally treated using block thermostats at set temperatures in order to determine time-temperature regimes to achieve sufficient bacterial and viral reduction, and to model the inactivation rate. Pasteurization at 70°C in saline solution was used as a comparison in terms of bacterial and viral reduction and was proven to be effective in rapidly reducing all organisms with the exception of PPV (decimal reduction time of 1.2 h). The results presented here can be used to construct time-temperature regimes in terms of bacterial inactivation, with D-values ranging from 0.37 h at 55°C to 22.5 h at 46.0°C and 0.45 h at 55.0°C to 14.5 h at 47.5°C for Salmonella Senftenberg W775 and Enterococcus faecalis, respectively and for relevant enteric viruses based on the ϕX174 phage with decimal reduction times ranging from 1.5 h at 55°C to 16.5 h at 46°C. Hence, the study implies that considerably lower treatment temperatures than 70°C can be used to reach a sufficient inactivation of bacterial pathogens and potential process indicator organisms such as the ϕX174 phage and raises the question whether PPV is a valuable process indicator organism considering its extreme thermotolerance.

Electron beam inactivation of selected microbial pathogens and indicator organisms in aerobically and anaerobically digested sewage sludge

Microbial pathogens in municipal sewage sludges need to be inactivated prior to environmental disposal. The efficacy of high energy (10 MeV) e-beam irradiation to inactivate a variety of selected microbial pathogens and indicator organisms in aerobically and anaerobically digested sewage sludge was evaluated. Both bacterial and viral pathogens and indicator organisms are susceptible to e-beam irradiation. However, as expected there was a significant difference in their respective e-beam irradiation sensitivity. Somatic coliphages, bacterial endospores and enteric viruses were more resistant compared to bacterial pathogens. The current US EPA mandated 10 kGy minimum dose was capable of achieving significant reduction of both bacterial and viral pathogens. Somatic coliphages can be used as a microbial indicator for monitoring e-beam processes in terms of pathogen inactivation in sewage sludges.

Free-living microscopic organisms as indicators of changes in drinking-water quality

Bacterial indicator organisms (e.g., coliforms, E. coli) and some chemical parameters (e.g., turbidity, ammonia) are basic monitoring tools used to measure both changes in drinking-water quality and the presence of hard-to-detect pathogenic bacteria, viruses and protozoa. Microscopically detectable free-living organisms, such as some groups of bacteria, fungi, nematodes, rotifers and protozoa, are usable as additional indicators of fecal or environmental contamination of drinking water as well as any changes in the drinking-water quality. Our aim in this paper is to summarize the results of microscopic examination of 913 drinking-water samples from different water sources in Hungary in 2004 and 2005 and to demonstrate how these results can be used to maintain safe and good-tasting drinking-water quality. A total of 277 drinking-water samples failed Hungarian microscopic water quality standards as a result of helminths (58%), protozoa (41%), iron bacteria (16%), sulfur bacteria (13%), fungi (11%), algae (5%) and multiple biological contaminants (34%). Based on these results, pipe washing or water storage tank cleaning was deemed necessary. In addition, a number of disinfection or filtration failures were found. Two detailed case studies show the usefulness of monitoring microscopic parameters to avoid disease outbreaks. To our knowledge this is the first paper discussing drinking-water microscopy based on Hungarian experience and practice, which could be useful and informative for other countries.

Occurrence and Persistence of Bacterial Pathogens and Indicator Organisms in Beach Sand along the California Coast

This report documents the presence of fecal indicators and bacterial pathogens in sand at 53 California marine beaches using both culture-dependent and -independent (PCR and quantitative PCR [QPCR]) methods. Fecal indicator bacteria were widespread in California beach sand, with Escherichia coli and enterococci detected at 68% and 94% of the beaches surveyed, respectively. Somatic coliphages and a Bacteroidales human-specific fecal marker were detected at 43% and 13% of the beaches, respectively. Dry sand samples from almost 30% of the beaches contained at least one of the following pathogens: Salmonella spp., Campylobacter spp., Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA), which were detected at 15%, 13%, 14%, and 3% of tested beaches, respectively. Fecal indicators and pathogens were poorly correlated to one another and to land cover. Sands were dry at the time of collection, and those with relatively high moisture tended to have higher concentrations or a more frequent occurrence of both indicators and pathogens. Using culture-dependent assays, fecal indicators decayed faster than pathogens in microcosm experiments using unaltered beach sand seeded with sewage and assessed by culture-dependent assays. The following order of persistence was observed (listed from most to least persistent): Campylobacter > Salmonella > somatic coliphages > enterococci > E. coli > F(+) phages. In contrast, pathogens decayed faster than fecal indicators in culture-independent assays: enterococci > Bacteroidales human-specific marker > Salmonella > Campylobacter. Microcosm experiments demonstrated that both indicators and pathogens were mobilized by wetting with seawater. Decay rates measured by QPCR were lower than those measured with culture-dependent methods. Enterococcal persistence and possible growth were observed for wetted microcosms relative to unwetted controls.

Sensitivity to disinfection of bacterial indicator organisms for monitoring the Salmonella Enteritidis status of layer farms after cleaning and disinfection

The present study evaluated Escherichia coli, Enterococcus faecalis, and Enterococcus hirae as potential indicator organisms for the possible Salmonella Enteritidis (SE) presence in layer farms after cleaning and disinfection by comparing their susceptibility to disinfection. A quantitative suspension disinfection test according to European Standard EN1656 was performed using disinfection products CID20 and Virocid (both from CID Lines, Ieper, Belgium). In a preliminary test, the sensitivity to both disinfection products was compared between ATCC strains of SE, E. coli, En. faecalis, and En. hirae. The sensitivity of SE to disinfection was most comparable to that of E. coli. A second disinfection test compared the elimination of E. coli to SE ATCC strains as well as field strains. Results showed no significant effect regarding the strain (P > 0.05 for CID20 and Virocid), meaning that no difference was detected in sensitivity toward disinfection. When comparing the sensitivity in general at species level for all concentrations of disinfectant used, no significant difference was found between E. coli and SE in sensitivity to Virocid (P > 0.05). In conclusion, because of its similar response to disinfection in a suspension disinfection test, E. coli could be used as an indicator for possible Salmonella presence after cleaning and disinfection.

Chlorine Disinfection of Blended Municipal Wastewater Effluents

Blending is used in the wastewater industry to manage wet-weather events. Wastewater is treated through primary clarification, with flows in excess of the hydraulic capacity of the secondary system being directed to effluent disinfection. Before disinfection, the primary clarified effluent is "blended" with effluents that have been treated through the secondary system. The combined or "blended" effluents are then disinfected before being discharged to receiving waters. This study evaluated the effectiveness of chlorine to disinfect blended effluents. Experiments were conducted at bench-scale on primary and secondary effluents and three ratios of primary to secondary effluent (1:9, 3:7, and 5:5) from three publicly owned treatment works. Results from this study found that blending 10% or more primary effluent with secondary reduces the efficacy of chlorine disinfection, and coliphage survived chlorine disinfection better than bacterial indicator organisms. A simple empirical model for predicting indicator organism densities following chlorine disinfection was developed using data from this research.

Production of a New Thiopeptide Antibiotic, TP-1161, by a Marine Nocardiopsis Species

Twenty-seven marine sediment- and sponge-derived actinomycetes with a preference for or dependence on seawater for growth were classified at the genus level using molecular taxonomy. Their potential to produce bioactive secondary metabolites was analyzed by PCR screening for genes involved in polyketide and nonribosomal peptide antibiotic synthesis. Using microwell cultures, conditions for the production of antibacterial and antifungal compounds were identified for 15 of the 27 isolates subjected to this screening. Nine of the 15 active extracts were also active against multiresistant gram-positive bacterial and/or fungal indicator organisms, including vancomycin-resistant Enterococcus faecium and multidrug-resistant Candida albicans. Activity-guided fractionation of fermentation extracts of isolate TFS65-07, showing strong antibacterial activity and classified as a Nocardiopsis species, allowed the identification and purification of the active compound. Structure elucidation revealed this compound to be a new thiopeptide antibiotic with a rare aminoacetone moiety. The in vitro antibacterial activity of this thiopeptide, designated TP-1161, against a panel of bacterial strains was determined.