Search

Awareness of the need for surveillance of antimicrobial resistance (AMR) in water environments is growing, but there is uncertainty regarding appropriate monitoring targets. Adapting culture-based fecal indicator monitoring to include antibiotics in the media provides a potentially low-tech and accessible option, while quantitative polymerase chain reaction (qPCR) targeting key genes of interest provides a broad, quantitative measure across the microbial community. The purpose of this study was to compare findings obtained from the culture of cefotaxime-resistant (cefR) Escherichia coli with two qPCR methods for quantification of antibiotic resistance genes across wastewater, recycled water, and surface waters. The culture method was a modification of US EPA Method 1603 for E. coli, in which cefotaxime is included in the medium to capture cefR strains, while qPCR methods quantified sul1 and intI1. A common standard operating procedure for each target was applied to samples collected by six water utilities across the United States and processed by two laboratories. The methods performed consistently, and all three measures reflected the same overarching trends across water types. The qPCR detection of sul1 yielded the widest dynamic range of measurement as an AMR indicator (7-log versus 3.5-log for cefR E. coli), while intI1 was the most frequently detected target (99% versus 96.5% and 50.8% for sul1 and cefR E. coli, respectively). All methods produced comparable measurements between labs (p < 0.05, Kruskal–Wallis). Further study is needed to consider how relevant each measure is to capturing hot spots for the evolution and dissemination of AMR in the environment and as indicators of AMR-associated human health risk. [ABSTRACT FROM AUTHOR]

One of the numerous responses to the mass shooting at Virginia Tech in April 2007 has been the call for higher education institutions in the United States to take an increased role in identifying troubled students. This has had widely felt effects, with educational institutions across the United States developing mechanisms such as Threat Assessment Teams to respond to the perceived heightened threat of campus violence. At the core of these responses is the notion of the troubled student that brings dangerousness and depression together. The purpose of this article is to draw attention to this, arguing that extreme violence has been extended from the provenance of the dangerous mad individual to a potential characteristic of the depressed individual. Interrogating this shift takes on special significance because understanding depression and violence is deemed vital to "connect the dots" to detect the troubled student, thereby preventing campus violence in higher education institutions. To consider this shifting conceptualization, this article draws closely on Hannah Arendt's distinction between factual and rational truths and Michel Foucault's analysis of melancholy. The Arendtian distinction between factual and rational truths facilitates analysis of the truths of the troubled student, as well as underscoring the importance that this recognition has for debate. Foucault's investigation of melancholy together with his emphasis on the "structure of perception" is employed to tease out how truths of the troubled student are produced, and thereby demonstrate that they are rational truths. Drawing on these ideas, the article offers a critical examination of how depression figures as potency and advances the argument that in the take-up of these emerging conceptualizations, there is a significant shift in how the troubled student is understood in higher education.

ABSTRACT One of the numerous responses to the mass shooting at Virginia Tech in April 2007 has been the call for higher education institutions in the United States to take an increased role in identifying troubled students. This has had widely felt effects, with educational institutions across the United States developing mechanisms such as Threat Assessment Teams to respond to the perceived heightened threat of campus violence. At the core of these responses is the notion of the troubled student that brings dangerousness and depression together. The purpose of this article is to draw attention to this, arguing that extreme violence has been extended from the provenance of the dangerous mad individual to a potential characteristic of the depressed individual. Interrogating this shift takes on special significance because understanding depression and violence is deemed vital to 'connect the dots' to detect the troubled student, thereby preventing campus violence in higher education institutions. To consider this shifting conceptualization, this article draws closely on Hannah Arendt's distinction between factual and rational truths and Michel Foucault's analysis of melancholy. The Arendtian distinction between factual and rational truths facilitates analysis of the truths of the troubled student, as well as underscoring the importance that this recognition has for debate. Foucault's investigation of melancholy together with his emphasis on the 'structure of perception' is employed to tease out how truths of the troubled student are produced, and thereby demonstrate that they are rational truths. Drawing on these ideas, the article offers a critical examination of how depression figures as potency and advances the argument that in the take-up of these emerging conceptualizations, there is a significant shift in how the troubled student is understood in higher education. [ABSTRACT FROM AUTHOR]

Rapid isolation of Salmonella from food is essential for faster typing and source tracking in an outbreak. The objective of this study was to investigate a rapid isolation method that would augment the standard U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM) method. Food samples with low microbial load, including egg salad and ice cream, moderately high-microbial-load tomatoes, and high-microbial-load ground beef were intentionally inoculated with 2 to 48 CFU of Salmonella enterica serotype Typhimurium. The samples were preenriched in buffered peptone water for 6 h, and then selectively concentrated by immunomagnetic separation and plated for isolation on xylose-lysine-desoxycholate agar: the 6IX method. Salmonella Typhimurium was presumptively identified from approximately 97% of the low-microbial-load and moderately high-microbial-load samples by the 6IX method 2 days before the BAM standard method for isolation of Salmonella. In 49% of the beef samples, Salmonella Typhimurium was presumptively identified 1 or 2 days earlier by the 6IX method. Given the inocula used, our data clearly indicated that for most of the food samples tested, with the exception of ground beef, Salmonella Typhimurium could be isolated two laboratory days earlier with the 6IX method compared with the BAM method. In conclusion, this 6IX method may expedite Salmonella isolation and, therefore, has the potential to accelerate strain tracking for epidemiological analysis in a foodborne outbreak. [ABSTRACT FROM AUTHOR]

Reports the isolation of coliform and fecal coliform bacteria from a subspecies of a diamondback terrapin Malaclemys terrapin centrata in estuarine waters of northeastern Florida. Description of the sampling sites; Sampling techniques; Isolation and enumeration of bacteria.

Millions of tons of fecal-contaminated poultry litter are applied to U.S. agricultural fields annually. Precipitation and irrigation facilitate transport of fecal-derived pathogens and fecal indicator bacteria (FIB) to groundwater. The goal of this study was to compare transport of pathogens, FIB, and a microbial source tracking marker gene for poultry litter (LA35) in a simulated soil-to-groundwater system. Nine laboratory soil columns containing four different soil types were used to evaluate microbial transport to groundwater via infiltration. Quantitative polymerase chain reaction was used to monitor Salmonella enterica Typhimurium, Escherichia coli , Enterococcus spp., Brevibacterium sp. LA35 and Bacteroidales leached from soil columns inoculated with poultry litter. S . enterica was correlated with LA35 poultry litter marker gene and FIB concentrations in column soils containing organic matter, but not in acid washed sands. In contrast, S . enterica was found to correlate with LA35 and FIB in the leachate from columns containing sand, but not with leachate from organic soil columns. The majority of recovered DNA was found in leachate of predominately sandy soil columns, and in the soil of loamy columns. At least 90% of the DNA retained in soils for each microbial target was found in the top 3 cm of the column. These studies suggest that poultry litter associated pathogens and FIB are rapidly released from litter, but are influenced by complex attenuation mechanisms during infiltration, including soil type. This study advances our understanding of the potential for subsurface transport of poultry litter associated pathogens and FIB, and support the use of the LA35 marker gene for evaluating poultry litter impacts on groundwater. [ABSTRACT FROM AUTHOR]

In the United States, total maximum daily load standards for bodies of water that do not meet bacterial water quality standards are set by each state. The presence of human polyomaviruses (HPyVs) can be used as an indicator of human-associated sewage pollution in these waters. We have developed and optimized a TaqMan quantitative PCR (QPCR) assay based on the conserved T antigen to both quantity and simultaneously detect two HPyVs; JC virus and BK virus. The QPCR assay was able to consistently quantify ≥10 gene copies per reaction and is linear over 5 orders of magnitude. HPyVs were consistently detected in human waste samples (57 of 64) and environmental waters with known human fecal contamination (5 of 5) and were not amplified in DNA extracted from 127 animal waste samples from 14 species. HPyV concentrations in sewage decreased 81.2 and 84.2% over 28 days incubation at 25 and 35°C, respectively. HPyVs results were compared to Escherichia coli, fecal coliform, and enterococci concentrations and the presence of three other human-associated microbes: Bacteroidetes, Methanobrevibacter smithii,and adenovirus. HPyVs were the most frequently detected of these in human and contaminated environmental samples and were more human specific than the Bacteroidetes (HF183) or M. smithii. HPyVs and M. smithii more closely mimicked the persistence of adenovirus in sewage than the other microbes. The use of this rapid and quantitative assay in water quality research could help regulatory agencies to identify sources of water pollution for improved remediation of contaminated waters and ultimately protect humans from exposure to pathogens. [ABSTRACT FROM AUTHOR]

Vibrio vulnificus is an autochthonous estuarine bacterium and a pathogen that is frequently transmitted via raw shellfish. Septicemia can occur within 24 h; however, isolation and confirmation from water and oysters require days. Real-time PCR assays were developed to detect and differentiate two 16S rRNA variants, types A and B, which were previously associated with environmental sources and clinical fatalities, respectively. Both assays could detect 10² to 10³ V. vulnificus total cells in seeded estuarine water and in oyster homogenates. PCR assays on 11 reference V. vulnificus strains and 22 nontarget species gave expected results (type A or B for V. vulnificus and negative for nontarget species). The relationship between cell number and cycle threshold for the assays was linear (R² = >0.93). The type A/B ratio of Florida clinical isolates was compared to that of isolates from oysters harvested in Florida waters. This ratio was 19:17 in clinical isolates and 5:8 (n = 26) in oysters harvested from restricted sites with poor water quality but was 10:1 (n = 22) in oysters from permitted sites with good water quality. A substantial percentage of isolates from oysters (19.4%) were type 413 (both primer sets amplified), but no isolates from overlying waters were type AB. The real-time PCR assays were sensitive, specific, and quantitative in water samples and could also differentiate the strains in oysters without requiring isolation of V. vulnificus and may therefore be useful for rapid detection of the pathogen in shellfish and water, as well as further investigation of its population dynamics. [ABSTRACT FROM AUTHOR]

Vibrio vulnificus causes rare but frequently fatal septicemia associated with raw oyster consumption by persons with underlying hepatic or immune system dysfunction. The virulence potential of environmental reservoirs appears widely distributed, because most strains are virulent in animal models; however, several investigations recently demonstrated genetic divergence among strains from clinical versus environmental origin at independent genetic loci. The present study used PCR to screen DNA polymorphisms in strains from environmental (n = 35) or clinical (n = 33) sources, and genomic relationships were determined by repetitive extragenic palindromic DNA PCR (rep-PCR) typing. Significant (P < 0.01) association was observed for typical ‘clinical’ or ‘environmental’ polymorphism profiles based on strain origin. Most oyster isolates (88%), including all of those with the ‘environmental’ profile, also formed a single rep-PCR genogroup. Clinical isolates within this group did not have the typical ‘clinical’ profile. On the other hand, clinical isolates with the typical polymorphism profile were distributed among multiple rep-PCR genogroups, demonstrating greater genetic diversity than was evident by profiling genetic polymorphisms. Wound isolates were genetically distinct from typical blood isolates by all assays. Strains from an outbreak of wound infections in Israel (biotype 3) were closely related to several U.S. strains by rep-PCR, indicating potential reservoirs of emerging disease. Strains genetically related to blood isolates appeared to be relatively rare in oysters, as only one had the ‘clinical’ polymorphism profile or clustered by rep-PCR. However, this study was not an extensive survey, and more sampling using rep-PCR for sensitive genetic discrimination is needed to determine the virulence potential of environmental reservoirs. [ABSTRACT FROM AUTHOR]

Examines the influence of marine bacteria in the colilert-18 rapid identification test for Escherichia coli in Florida. Determination of fecal coliform counts by membrane filtration; Use of coliform bacteria as indicators of fecal contamination in fresh and marine waters; Expression of enzyme beta-D-glucuronide.

The gram-negative bacterium Vibrio vulnificus is a natural inhabitant of estuarine waters and poses a significant health threat to humans who suffer from immune disorders, liver disease, or hemochromatosis (iron overload). V. vulnificus enters human hosts via wound infections or consumption of raw shellfish (primarily oysters), and infections frequently progress to septicemia and death in susceptible individuals. Prevalence in waters and shellfish is not correlated with fecal indicator organisms; therefore, species-specific detection and enumeration of V. vulnificus in the environment has become a priority for agencies that are responsible for shellfish safety. The many selective-differential media developed for isolation of Vibrio spp., and specifically for V. vulnificus detection, are reviewed here; however, none of the media developed to date combines the sensitivity to low numbers with the specificity necessary to inhibit growth of other organisms. Therefore, immunological and molecular protocols are needed for confirmation of the identity of the organism and are discussed in detail. Methods under development that hold promise for rapid, accurate, and sensitive detection and enumeration of the organism include multiplex and real-time PCR. Developing technologies that have proven useful for detection and investigation of other pathogens such as biosensors, spectroscopy and microarrays may provide the next generation of tools for investigation of the prevalence and ecology of V. vulnificus.