Presence Of Indicator Bacteria Research Articles

Predicting groundwater contamination to protect the storm-exposed vulnerable

Domestic wells provide drinking water to 44 million people nationwide. Many of these wells, which remain federally unregulated and rarely tested for pollutants, serve rural populations clustered near surface-contaminated sites (e.g., hazardous waste sites, animal agriculture operations, coal ash ponds, etc.). The potential for natural disasters to deteriorate drinking water quality is well documented. Less understood is whether opportunistic post-disaster sampling might underrepresent vulnerable populations. When disaster strikes, well water sampling campaigns offer a glimpse into the quality of water for exposed residents. We examined over 8,000 well water samples from 2016 and 2017 to measure Hurricane Matthew’s impact on the presence of indicator bacteria. Bacteria presence was predicted at the household level following Hurricane Matthew’s landfall. The residential addresses associated with birth records as well as clinically estimated dates of conception and birth dates were used to predict the likelihood of indicator bacteria in drinking water sources that were unsampled but likely to have served pregnant women. We estimate that opportunistic well water sampling captures the average predicted contamination rates among households with pregnant women. Our approach documents a distribution of contamination risk where 2.7% of the vulnerable sample (670 unsampled households) have a 75% likelihood of total coliform presence. The predicted likelihood of indicator bacteria is elevated for a small share of households nearby swine lagoons that experienced the most torrential rainfall. However, the gap between sampled and unsampled households cannot otherwise be explained by the storm event or proximity to surface-contaminated sites. Findings suggest that sophisticated and holistic water quality prediction models may support post-disaster sampling campaigns by targeting individual households within vulnerable groups that are likely to experience higher risks from groundwater contamination.

Presence and Correlation of Some Enteric Indicator Bacteria, Diarrheagenic Escherichia coli Pathotypes, and Salmonella Serotypes in Alfalfa Sprouts from Local Retail Markets in Pachuca, Mexico

Data on the presence of diarrheagenic Escherichia coli pathotypes (DEPs) in alfalfa sprouts and correlations between the presence of coliform bacteria (CB), fecal coliforms (FC), E. coli, DEPs, and Salmonella in alfalfa sprouts are not available. The presence of and correlations between CB, FC, E. coli, DEPs, and Salmonella in alfalfa sprouts were determined. One hundred sprout samples were collected from retail markets in Pachuca, Hidalgo State, Mexico. The presence of indicator bacteria and Salmonella was determined using conventional culture procedures. DEPs were identified using two multiplex PCR procedures. One hundred percent of samples were positive for CB, 90% for FC, 84% for E. coli, 10% for DEPs, and 4% for Salmonella. The populations of CB ranged from 6.2 up to 8.6 log CFU/g. The FC and E. coli concentrations were between , 3 and 1,100 most probable number (MPN)/g. The DEPs identified included enterotoxigenic E. coli (ETEC; 2%), enteropathogenic E. coli (EPEC; 3%), and Shiga toxin-producing E. coli (STEC; 5%). No E. coli O157:H7 strains were detected in any STEC-positive samples. In samples positive for DEPs, the concentrations ranged from 210 to 240 MPN/g for ETEC, 28 to 1,100 MPN/g for EPEC, and 3.6 to 460 MPN/g for STEC. The Salmonella isolates identified included Salmonella enterica serotype Typhimurium in three samples and Salmonella enterica serotype Enteritidis in one. STEC and Salmonella Typhimurium were identified together in one sample. Positive correlations were observed between FC and E. coli, between FC and DEPs, and between E. coli and DEPs. Negative correlations occurred between CB and DEPs and between CB and Salmonella. Neither FC nor E. coli correlated with Salmonella in the sprout samples. To our knowledge, this is the first report of ETEC, EPEC, and STEC isolated from alfalfa sprouts and the first report of correlations between different indicator groups versus DEPs and Salmonella.

Presence of indicator bacteria, Salmonella and diarrheagenic Escherichia coli pathotypes on mung bean sprouts from public markets in Pachuca, Mexico

Coliform bacteria (CB), fecal coliforms (FC), Escherichia coli, diarrheagenic E. coli pathotypes (DEP) and Salmonella frequencies were determined for mung bean (Vigna radiata) sprouts. One hundred sprout samples were collected from markets in Pachuca, Hidalgo state, Mexico. Of these samples, 100% were positive for CB, 98% for FC, 95% for E. coli, 10% for DEP and 5% for Salmonella. Identified DEP included enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and Shiga toxin-producing E. coli (STEC). The ETEC and EIEC were each isolated from 2% of samples, and the STEC from 6% of samples. No E. coli O157:H7 were detected in any STEC-positive samples. Positive correlations were observed between FC and E. coli and between E. coli and DEP. A negative correlation occurred between CB and DEP, and between CB and Salmonella. Neither FC nor E. coli correlated with Salmonella presence in the sprout samples. This is the first report of ETEC, EIEC and STEC isolated from sprouts in Mexico and the first report of Salmonella isolation from mung bean in Mexico. Mung bean sprouts are very probably an important factor contributing to the endemicity of ETEC, EIEC and STEC and Salmonella-related gastroenteritis in Mexico.

Profile of Antimicrobial Resistance ofStaphylococcus aureusand Molecular Epidemiologic Characterization of Methicillin-resistantStaphylococcus aureus(MRSA) Isolated from Hands of People Using Multitude Facilities

Background: The purpose of this study was to investigate perception of hand hygiene and actual hand washing practices of people who used public facilities as well as the presence of indicator bacteria and food-borne pathogens on their hands. Data from this study will be used as a tool for public edu...

A membrane coupled to a sequencing batch reactor for water reuse and removal of coliform bacteria

Wastewater reclamation was studied by using a small biological reactor and an external filtration membrane coupled in series. Use of the membrane enhanced the quality of the effluent of the biological reactor in terms of suspended solids and presence of indicator bacteria. Partial removal of faecal coliforms and Escherichia coli was observed in the effluent of a sequencing batch reactor (SBR) previous to filtration by the membrane. Use of the membrane ensured full removal of the indicator bacteria in the final permeate. More than 95% of organic matter, suspended solids, and coliform bacteria were successfully removed. The operation and behaviour of internal submerged membranes in two different bioreactors was an additional objective. For this reason, two configurations—a membrane coupled to a SBR (MSBR) and a continuous membrane bioreactor (MBR)—were used during the study. Particular attention was focused on fouling and hydraulic conditions in the membranes. Fouling could be reduced by maintaining turbulent conditions and by operating at sub-critical flux.

Evidence for rapid groundwater flow and karst-type behaviour in the Chalk of southern England

With the growing importance of groundwater protection, there is increasing concern about the possibility of rapid groundwater flow in the Chalk of southern England and therefore in the frequency and distribution of ‘karstic’ features. Pumping test data, although useful in quantifying groundwater resources and regional flow, give little information on groundwater flow at a local scale. Evidence for rapid groundwater flow is gathered from other, less quantifiable methods. Nine different strands of evidence are drawn together: tracer tests; observations from Chalk caves; Chalk boreholes that pump sand; descriptions of adits; the nature of water-level fluctuations; the Chichester flood; the nature of the surface drainage; geomorphological features; and the presence of indicator bacteria in Chalk boreholes. Although the evidence does not prove the widespread existence of karstic features, it does suggest that rapid groundwater flow should be considered seriously throughout the Chalk. Rapid groundwater flow is generally more frequent close to Palaeogene cover and may also be associated with other forms of cover and valley bottoms.

Disinfection, Recontamination and Regrowth of Indicator Bacteria in a Wastewater Sludge Heat Treatment System

The largest sewage treatment plant in Hawaii produces 25,400 kg/day of primary sludge that is heat-treated (190°C) under 330 psig for 3 0 min. Although this treatment should result in a sterilized sludge product, the final sludge cake often contains high concentrations of fecal-borne indicator bacteria. The heat-treatment process was shown to disinfect the sludge of indicator bacteria. However, post contamination of the heat-treated sludge by raw sludge and by chlorinated primary effluent and the regrowth of indicator bacteria in the sludge storage tanks resulted in the presence of indicator bacteria in the sludge cake.