False-positive identification ofEscherichia coliin treated municipal wastewater and wastewater-irrigated soils

2011 ◽  
Vol 57 (10) ◽  
pp. 775-784 ◽  
Author(s):  
Jean E.T. McLain ◽  
Channah M. Rock ◽  
Kathleen Lohse ◽  
James Walworth
Keyword(s):  
Water Quality ◽  
False Positive ◽  
Municipal Wastewater ◽  
Inorganic Compounds ◽  
Treated Wastewater ◽  
Technical Literature ◽  
E Coli ◽  
Positive Identification ◽  
False Positive Identification ◽  
Irrigated Soils

The increasing use of treated wastewater for irrigation heightens the importance of accurate monitoring of water quality. Chromogenic media, because they are easy to use and provide rapid results, are often used for detection of Escherichia coli in environmental samples, but unique levels of organic and inorganic compounds alter the chemistry of treated wastewater, potentially hindering the accurate performance of chromogenic media. We used MI agar and molecular confirmatory methods to assess false-positive identification of E. coli in treated wastewater samples collected from municipal utilities, an irrigation holding pond, irrigated soils, and in samples collected from storm flows destined for groundwater recharge. False-positive rates in storm flows (4.0%) agreed closely with USEPA technical literature but were higher in samples from the pond, soils, and treatment facilities (33.3%, 38.0%, and 48.8%, respectively). Sequencing of false-positive isolates confirmed that most were, like E. coli, of the family Enterobacteriaceae, and many of the false-positive isolates were reported to produce the β-d-glucuronidase enzyme targeted by MI agar. False-positive identification rates were inversely related to air temperature, suggesting that seasonal variations in water quality influence E. coli identification. Knowledge of factors contributing to failure of chromogenic media will lead to manufacturer enhancements in media quality and performance and will ultimately increase the accuracy of future water quality monitoring programs.

scholarly journals Population Admixture May Appear to Mask, Change or Reverse Genetic Effects of Genes Underlying Complex Traits

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1319-1323
Author(s):  
Hong-Wen Deng
Keyword(s):  
Population Genetics ◽  
False Positive ◽  
Complex Traits ◽  
Association Studies ◽  
Genetic Effects ◽  
Population Admixture ◽  
Reverse Genetic ◽  
Positive Identification ◽  
False Positive Identification

Abstract Association studies using random population samples are increasingly being applied in the identification and inference of genetic effects of genes underlying complex traits. It is well recognized that population admixture may yield false-positive identification of genetic effects for complex traits. However, it is less well appreciated that population admixture can appear to mask, change, or reverse true genetic effects for genes underlying complex traits. By employing a simple population genetics model, we explore the effects and the conditions of population admixture in masking, changing, or even reversing true genetic effects of genes underlying complex traits.

False Positive Identification

1978 ◽  
Vol 18 (4) ◽  
pp. 255-262 ◽  
Author(s):  
E. Linden Hilgendorf ◽  
B. L. Irving
Keyword(s):  
False Positive ◽  
Waiting Room ◽  
Positive Identification ◽  
False Positive Identification ◽  
High Level

This paper reports the results of a simulation of an identification parade using recommended procedures. The parade was held three days after subjects had been incidental observers of a man in a waiting room. The Parade included ‘a suspect’ who was not the man Previously seen. Of the 68 subjects, 21 made a false Positive identification on the parade, including 6 who made an identification with a high level of certainty. All these 6 high certainty identifications were of ‘the suspect’. A group of subjects also saw a set of photographs prior to the parade. The findings suggest that, When the man previously seen was not included, subjects were more likely to make a false positive identification on photographs than on a parade. In addition, subjects who had seen the photographs Wade a significantly greater proportion of false positive identifications on the subsequent parade.

scholarly journals Managing Risks Associated with Establishing the Metabolome of Dietary Phytochemicals (P06-010-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Colin Kay ◽  
Jessica Everhart ◽  
Atul Rathore
Keyword(s):  
Gas Phase ◽  
False Positive ◽  
Method Development ◽  
Ion Trap ◽  
Reference Standards ◽  
Molecular Rearrangement ◽  
Positive Identification ◽  
Hydrogen Elimination ◽  
False Positive Identification ◽  
Dietary Phytochemicals

Abstract Objectives Establishing the metabolome of dietary phytochemicals is complicated by the influence of the microbiome. Due to large numbers of human, microbial and hybrid human-microbial metabolites, false-positive identification via mass spectrometry (MS) is probable. Users must be aware of the influence of matrix and instrumental background environment upon the mass spectrum, which produce spectral features arising from fragmentation, gas-phase artifacts, molecular rearrangement, quasi-molecular ion or radical formation. Hydroxylated cyclic and polycyclic structures such as polyphenols are prone to multiple gas-phase artifacts, including water elimination (loss −17), hydrogen elimination (−1), radical fragmentation (loss −15, −14), Retro-Diels-Alder reactions (C-ring electron rearrangement; + or −2), or combinations thereof. In-source fragmentation is often observed for phase II conjugates, such as sulfate, glucuronide and glycine. Finally, polyphenol metabolites such as valerolactones, benzoic, phenylpropanoic and phenylacetic acids, are also products of MS fragmentation. As there are few reference standards available for confirmation or optimization, false-positive identification is likely. The objective of the present study was to highlight limitations with MS to ensure researchers make appropriate assumptions from their spectral data. Methods A quantitative metabolomics database comprising optimized spectral signals for fragmentation profiling of over 400 poly/phenols and metabolites was established using a UHPLC-coupled electrospray triple quadrupole-linear ion trap mass spectrometer (SCIEX QTRAP 6500+). Methods were established and utilized to interrogate over 3000 biospecimens derived from studies feeding various polyphenol-rich diets. Results Scanning for numerous metabolites reported in the literature using single transition monitoring, in both neat and extracted human and animal tissue matrices consistently identify peaks which were either artifacts, isomers, fragments or background noise, as confirmed relative to authentic reference standards. Conclusions Without ample MS experience, method development, validation and data interrogation, falsely identified metabolites will continue to occur and undoubtedly hinder future discovery. Funding Sources NIFA-USDA Hatch 1011757.

scholarly journals The occurrence of antibiotic-resistant bacteria, including Escherichia coli, in municipal wastewater and river water

2019 ◽  
Vol 100 ◽  
pp. 00061 ◽  
Author(s):  
Adriana Osińska ◽  
Ewa Korzeniewska ◽  
Monika Harnisz ◽  
Sebastian Niestępski ◽  
Piotr Jachimowicz
Keyword(s):  
Escherichia Coli ◽  
Wastewater Treatment ◽  
River Water ◽  
Municipal Wastewater ◽  
High Efficiency ◽  
Treated Wastewater ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
E Coli

Wastewater treatment plants (WWTPs) are major reservoirs of antibiotic-resistant bacteria (ARB) which are transported to the natural environment with discharged effluents. Samples of untreated wastewater (UWW) and treated wastewater (TWW) from four municipal WWTPs and samples of river water collected upstream (URW) and downstream (DRW) from the effluent discharge point were analyzed in the study. The total counts of bacteria resistant to β-lactams and tetracyclines and the counts of antibiotic-resistant Escherichia coli were determined. Antibiotic-resistant bacteria, including antibiotic-resistant E. coli, were removed with up to 99.9% efficiency in the evaluated WWTPs. Despite the above, ARB counts in TWW samples were high at up to 1.25x105 CFU/mL in winter and 1.25x103 CFU/mL in summer. Antibiotic-resistant bacteria were also abundant (up to 103 CFU/ml) in URW and DRW samples collected in winter and summer. In both UWW and TWW samples, the counts of ARB and antibiotic-resistant E. coli were at least one order of magnitude lower in summer than in winter. The study revealed that despite the high efficiency of bacterial removal in the wastewater treatment processes, considerable amounts of ARB are released into the environment with TWW and that the percentage of ARB in total bacterial counts increases after wastewater treatment.

scholarly journals Resistance of Escherichia coli and Enterococcus spp. to selected antimicrobial agents present in municipal wastewater

2013 ◽  
Vol 11 (4) ◽  
pp. 600-612 ◽  
Author(s):  
Aneta Luczkiewicz ◽  
Ewa Felis ◽  
Aleksandra Ziembinska ◽  
Anna Gnida ◽  
Ewa Kotlarska ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Municipal Wastewater ◽  
Antimicrobial Agents ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Treatment Plant ◽  
Treated Wastewater ◽  
E Coli ◽  
Enterococcus Spp ◽  
Gradient Gel Electrophoresis ◽  
Bacterial Biodiversity

In this study, the susceptibility to erythromycin (E) and to trimethoprim/sulfamethoxazole (SXT) among isolates of Enterococcus spp. and Escherichia coli was tested, respectively. Both fecal indicators were detected and isolated from raw (RW) and treated wastewater (TW) as well as from samples of activated sludge (AS) collected in a local wastewater treatment plant (WWTP). Biodiversity of bacterial community in AS was also monitored using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Additionally, distribution of sul1–3 genes conferring sulfonamide resistance was tested among SXT-resistant E. coli. Simultaneously, basic physicochemical parameters and concentrations of eight antimicrobial compounds (belonging to folate pathway inhibitors and macrolides class) were analyzed in RW and TW samples. Six of the selected antimicrobial agents, namely: erythromycin, clarithromycin, trimethoprim, roxithromycin, sulfamethoxazole, and N-acetyl-sulfamethoxazole were detected in the wastewater samples. Bacterial biodiversity of AS samples were comparable with no relevant differences. Among tested Enterococcus spp., E-resistant isolates constituted 41%. SXT resistance was less prevalent in E. coli with 11% of isolates. The genes conferring resistance to sulfonamides (sul1–3) were detected in SXT-resistant E. coli of wastewater origin with similar frequencies as in other environmental compartments, including clinical ones.

scholarly journals Evidence of Naturalized Stress-Tolerant Strains of Escherichia coli in Municipal Wastewater Treatment Plants

2016 ◽  
Vol 82 (18) ◽  
pp. 5505-5518 ◽  
Author(s):  
Shuai Zhi ◽  
Graham Banting ◽  
Qiaozhi Li ◽  
Thomas A. Edge ◽  
Edward Topp ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Wastewater Treatment ◽  
Intergenic Region ◽  
Municipal Wastewater ◽  
Treated Wastewater ◽  
Content Type ◽  
E Coli ◽  
Biomarker Pattern ◽  
Biomarker Analysis ◽  
Pcr Targeting

ABSTRACTEscherichia colihas been proposed to have two habitats—the intestines of mammals/birds and the nonhost environment. Our goal was to assess whether certain strains ofE. colihave evolved toward adaptation and survival in wastewater. Raw sewage samples from different treatment plants were subjected to chlorine stress, and ∼59% of the survivingE. colistrains were found to contain a genetic insertion element (IS30) located within theuspC-flhDCintergenic region. The positional location of the IS30element was not observed across a library of 845E. coliisolates collected from various animal hosts or within GenBank or whole-genome reference databases for human and animalE. coliisolates (n= 1,177). Phylogenetics clustered the IS30element-containing wastewaterE. coliisolates into a distinct clade, and biomarker analysis revealed that these wastewater isolates contained a single nucleotide polymorphism (SNP) biomarker pattern that was specific for wastewater. These isolates belonged to phylogroup A, possessed generalized stress response (RpoS) activity, and carried the locus of heat resistance, features likely relevant to nonhost environmental survival. Isolates were screened for 28 virulence genes but carried only thefimHmarker. Our data suggest that wastewater contains a naturalized resident population ofE. coli. We developed an endpoint PCR targeting the IS30element within theuspC-flhDCintergenic region, and all raw sewage samples (n= 21) were positive for this marker. Conversely, the prevalence of this marker inE. coli-positive surface and groundwater samples was low (≤5%). This simple PCR assay may represent a convenient microbial source-tracking tool for identification of water samples affected by municipal wastewater.IMPORTANCEThe results of this study demonstrate that some strains ofE. coliappear to have evolved to become naturalized populations in the wastewater environment and possess a number of stress-related genetic elements likely important for survival in this nonhost environment. The presence of non-host-adapted strains in wastewater challenges our understanding of usingE. colias a microbial indicator of wastewater treatment performance, suggesting that theE. colistrains present in human and animal feces may be very different from those found in treated wastewater.

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