PROBLEMS IN THE RECOVERY AND IDENTIFICATION OF ENTEROPATHOGENIC ESCHERICHIA COLI FROM FOODS1

1974 ◽  
Vol 37 (6) ◽  
pp. 350-356 ◽  
Author(s):  
Ira J. Mehlman ◽  
Nicholas T. Simon ◽  
Arvey C. Sanders ◽  
Joseph C. Olson
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reduction ◽  
Future Research ◽  
Decarboxylase Activity ◽  
Lauryl Sulfate ◽  
Critical Factors ◽  
Macconkey Agar ◽  
E Coli ◽  
Recent Outbreak ◽  
Indole Production

During a recent outbreak of gastroenteritis associated with serogroup 0124:B17 of Escherichia coli, various problems complicated recovery and identification of the pathogen. Standard methods for E. coli were of limited value because of atypical behavior of isolates. Two modified recovery procedures have been presented. For rapid lactose fermenters, pre-enrichment in MacConkey broth with subsequent transfer to lauryl sulfate tryptose broth and incubation at 44 C is recommended. For slow lactose fermenters, pre-enrichment in nutrient broth with subsequent transfer to Mossel's enteric enrichment broth and incubation at 41.5 C is tentatively proposed. Isolation agars include Levine's eosin methylene blue for lactose fermenters and MacConkey agar for non-lactose fermenters. The merits of a direct streak are considered. To facilitate rapid differentiation of E. coli from closely related Enterobacteriaceae within 3 days a modified Lundbeck procedure is offered. Isolates are first screened for H2S formation, indole production, arabinose fermentation, urease and ONPG-ase. Secondary characterization based on results of the indole and TSI reactions includes Voges-Proskauer test (22 C), lysine decarboxylase activity, KCN tolerance, and fermentation of adonitol, cellobiose, sorbitol, or glucose. Confirmation by gram-reaction nitrate reduction, and cytochrome oxidase activity is required to differentiate from members of other families. Critical factors of serological analysis are stressed. Prospects for future research are discussed.

scholarly journals Prevalence of enterotoxigenic and Shiga toxin-producing Escherichia coli in pigs slaughtered in Mato Grosso, Brazil

2010 ◽  
Vol 5 (02) ◽  
pp. 123-127 ◽  
Author(s):  
Rodrigo Prado Martins ◽  
Maria Cristina Da Silva ◽  
Valeria Dutra ◽  
Luciano Nakazato ◽  
Domingos da Silva Leite
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Enterotoxigenic Escherichia Coli ◽  
Future Research ◽  
Macconkey Agar ◽  
Mato Grosso ◽  
E Coli ◽  
Pcr Assays ◽  
Porcine Origin ◽  
Stx2 Gene

Introduction: This study aimed to estimate the prevalence of enterotoxigenic Escherichia coli (ETEC) and Shiga toxin-producing Escherichia coli (STEC) strains in pigs slaughtered in abattoirs located in the state of Mato Grosso, Brazil. Methodology: Intestinal samples from 74 animals were aseptically dissected and lumen content was plated on MacConkey agar. Confluent colonies from each plate were screened for the presence of ETEC and STEC strains by PCR assays. Results: It was verified that the prevalence of STEC and ETEC carriers was 1.35% and 9.46% respectively. One (1.35%) of the 74 samples tested was positive for the stx2 gene, and seven (9.46%) for st1, of which two (2.70%) were also positive for lt1. Conclusion: The results provided represent a benchmark for future research on pathogenic E. coli of porcine origin in Mato Grosso. 

scholarly journals A Pathoadaptive Deletion in an Enteroaggregative Escherichia coli Outbreak Strain Enhances Virulence in a Caenorhabditis elegans Model

2010 ◽  
Vol 78 (9) ◽  
pp. 4068-4076 ◽  
Author(s):  
Jennifer Hwang ◽  
Lisa M. Mattei ◽  
Laura G. VanArendonk ◽  
Philip M. Meneely ◽  
Iruka N. Okeke
Keyword(s):  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Genetic Material ◽  
Decarboxylase Activity ◽  
Multicopy Plasmid ◽  
Lysine Decarboxylase ◽  
Outbreak Strain ◽  
E Coli ◽  
C Elegans

ABSTRACT Enteroaggregative Escherichia coli (EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulent E. coli subtypes of Shigella and enterohemorrhagic E. coli. To test the hypothesis that cad deletions might account for heterogeneity in EAEC virulence, we developed a Caenorhabditis elegans pathogenesis model. Well-characterized EAEC strains were shown to colonize and kill C. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysine in vitro due to deletions in cadA and cadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of the cadAB genes. Strain 101-1 was significantly more lethal to C. elegans than control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion of cad genes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.

scholarly journals A New Clone Sweeps Clean: the Enigmatic Emergence of Escherichia coli Sequence Type 131

2014 ◽  
Vol 58 (9) ◽  
pp. 4997-5004 ◽  
Author(s):  
Ritu Banerjee ◽  
James R. Johnson
Keyword(s):  
Escherichia Coli ◽  
Sequence Type ◽  
Rapid Expansion ◽  
Future Research ◽  
Content Type ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
Phylogenetic Studies ◽  
Ecological Success

ABSTRACTEscherichia colisequence type 131 (ST131) is an extensively antimicrobial-resistantE. coliclonal group that has spread explosively throughout the world. Recent molecular epidemiologic and whole-genome phylogenetic studies have elucidated the fine clonal structure of ST131, which comprises multiple ST131 subclones with distinctive resistance profiles, including the (nested) H30, H30-R, and H30-Rx subclones. The most prevalent ST131 subclone, H30, arose from a single common fluoroquinolone (FQ)-susceptible ancestor containing allele 30 offimH(type 1 fimbrial adhesin gene). An early H30 subclone member acquired FQ resistance and launched the rapid expansion of the resulting FQ-resistant subclone, H30-R. Subsequently, a member of H30-R acquired the CTX-M-15 extended-spectrum beta-lactamase and launched the rapid expansion of the CTX-M-15-containing subclone within H30-R, H30-Rx. Clonal expansion clearly is now the dominant mechanism for the rising prevalence of both FQ resistance and CTX-M-15 production in ST131 and inE. coligenerally. Reasons for the successful dissemination and expansion of the key ST131 subclones remain undefined but may include increased transmissibility, greater ability to colonize and/or persist in the intestine or urinary tract, enhanced virulence, and more-extensive antimicrobial resistance compared to otherE. coli. Here we discuss the epidemiology and molecular phylogeny of ST131 and its key subclones, possible mechanisms for their ecological success, implications of their widespread dissemination, and future research needs.

Comparison of a New Enrichment Procedure for Shiga Toxin–Producing Escherichia coli with Five Standard Methods

2005 ◽  
Vol 68 (8) ◽  
pp. 1593-1599 ◽  
Author(s):  
MICHAEL A. GRANT
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Shiga Toxin ◽  
Real Time Pcr ◽  
Target Cells ◽  
Macconkey Agar ◽  
Standard Methods ◽  
E Coli ◽  
Canadian Health ◽  
Health Products

A new procedure for enrichment of Escherichia coli O157:H7 and other Shiga toxin–producing E. coli was compared to five standard methods: the British Public Health Laboratory Service, International Standard Method, U.S. Department of Agriculture, Canadian Health Products and Food Branch, and U.S. Food and Drug Administration. The new procedure was comparable to the standard methods in its ability to detect target cells inoculated into foods at approximately 1 CFU g−1. Comparisons were also made of the ability of the six enrichment procedures to detect E. coli O157:H7 against a large background of competitor microorganisms. In these experiments the new procedure yielded more target cells than the other five enrichments by two to three orders of magnitude as determined by enumeration on sorbitol MacConkey agar with tellurite and cefixime and Rainbow agar with tellurite and novobiocin and by verification of presumptive colonies by real-time PCR. For example, the population of enterohemorrhagic E. coli strain 6341 recovered on sorbitol MacConkey agar with tellurite and cefixime after enrichment with the experimental method was 2.42 × 108 CFU ml−1 and 1.80 × 106 CFU ml−1 after enrichment with the Canadian Health Products and Food Branch method, the second most effective in this experiment. In addition, broth cultures resulting from each of the six enrichment procedures were used to prepare templates for real-time PCR detection of stx1/stx2. Resulting threshold cycle (Ct) values after the experimental enrichment were similar to positive control values, whereas the five standard methods produced delayed Ct values or were not detected.

Presence and Antimicrobial Resistance of Escherichia coli in Ready-to-Eat Foods in Shaanxi, China

2017 ◽  
Vol 80 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Allah Bux Baloch ◽  
Hua Yang ◽  
Yuqing Feng ◽  
Meili Xi ◽  
Qian Wu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Shaanxi Province ◽  
Future Research ◽  
E Coli ◽  
Class 1 Integrons ◽  
Toxin Genes ◽  
Class 1 ◽  
Shiga Toxin Genes ◽  
Cooked Meat

ABSTRACT The aim of this study was to determine the presence and characteristics of Escherichia coli in ready-to-eat (RTE) foods. A total of 300 RTE foods samples were collected in Shaanxi Province, People's Republic of China: 50 samples of cooked meat, 165 samples of vegetable salad, 50 samples of cold noodles, and 35 samples of salted boiled peanuts. All samples were collected during summer (in July to October) 2011 and 2012 and surveyed for the presence of E. coli. E. coli isolates recovered were classified by phylogenetic typing using a PCR assay. The presence of Shiga toxin genes 1 (stx1) and 2 (stx2) was determined for these E. coli isolates by PCR, and all isolates were analyzed for antimicrobial susceptibility and the presence of class 1 integrons. Overall, 267 (89.0%) RTE food samples were positive for E. coli: 49 cold noodle, 46 cooked meat, 150 salad vegetable, and 22 salted boiled peanut samples. Of the 267 E. coli isolates, 73.0% belong to phylogenetic group A, 12.4% to group B1, 6.4% to group B2, and 8.2% to group D. All isolates were negative for both Shiga toxin genes. Among the isolates, 74.2% were resistant to at least one antimicrobial agent, and 17.6% were resistant to three or more antimicrobial agents. Resistance to ampicillin (75.6% of isolates) and tetracycline (73.1% of isolates) was most frequently detected; 26.2% of E. coli isolates and 68.8% of multidrug-resistant E. coli isolates were positive for class 1 integrons. All isolates were sensitive to amikacin. Our findings indicate that RTE foods in Shaanxi were commonly contaminated with antibiotic-resistant E. coli, which may pose a risk for consumer health and for transmission of antibiotic resistance. Future research is warranted to track the contamination sources and develop appropriate steps that should be taken by government, industry, and retailers to reduce microbial contamination in RTE foods.

Modeling Preharvest and Harvest Interventions for Escherichia coli O157 Contamination of Beef Cattle Carcasses

2011 ◽  
Vol 74 (9) ◽  
pp. 1422-1433 ◽  
Author(s):  
CHARLES C. DODD ◽  
MICHAEL W. SANDERSON ◽  
MEGAN E. JACOB ◽  
DAVID G. RENTER
Keyword(s):  
Escherichia Coli ◽  
Assessment Model ◽  
Sensitivity Analyses ◽  
Feed Additive ◽  
Future Research ◽  
Escherichia Coli O157 ◽  
Concentration Effects ◽  
Modeling Framework ◽  
E Coli ◽  
Carcass Contamination

Field studies evaluating the effects of multiple concurrent preharvest interventions for Escherichia coli O157 are logistically and economically challenging; however, modeling techniques may provide useful information on these effects while also identifying crucial information gaps that can guide future research. We constructed a risk assessment model with data obtained from a systematic search of scientific literature. Parameter distributions were incorporated into a stochastic Monte Carlo modeling framework to examine the impacts of different combinations of preharvest and harvest interventions for E. coli O157 on the risk of beef carcass contamination. We estimated the risk of E. coli O157 carcass contamination conditional on preharvest fecal prevalence estimates, inclusion of feed additive(s) in the diet, vaccination for E. coli O157, transport and lairage effects, hide intervention(s), and carcass intervention(s). Prevalence parameters for E. coli O157 were assumed to encompass potential effects of concentration; therefore, concentration effects were not specifically evaluated in this study. Sensitivity analyses revealed that fecal prevalence, fecal-to-hide transfer, hide-to-carcass transfer, and carcass intervention efficacy significantly affected the risk of carcass contamination (correlation coefficients of 0.37, 0.56, 0.58, and −0.29, respectively). The results indicated that combinations of preharvest interventions may be particularly important for supplementing harvest interventions during periods of higher variability in fecal shedding prevalence (i.e., summer). Further assessments of the relationships among fecal prevalence and concentration, hide contamination, and subsequent carcass contamination are needed to further define risks and intervention impacts for E. coli O157 contamination of beef.

scholarly journals Detection of auto-transporter Sat and Vat genes among Escherichia coli strains isolated from urinary tract infections

2019 ◽  
Vol 23 (10) ◽  
pp. 40 ◽  
Author(s):  
Wisal R. Yaseen AL- Hayali1 ◽  
Alaa Younis Mahdy2 ◽  
Muhammad Abdul Zaraq Ibrahim3
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Urinary Tract Infections ◽  
Duplex Pcr ◽  
Macconkey Agar ◽  
Biochemical Tests ◽  
E Coli ◽  
Genes Encoding ◽  
Tract Infections ◽  
Pcr Techniques

This study was designed to detect the presence of genes encoding autotranspoter proteins in E. coli that causes UTI by using PCR techniques. Seventy two urine sample were collected from patients infected with UTI whom attended to Salah-AL-deen general hospital in Tikrit city, during three months period (September to November 2016). All samples were cultivated on Blood agar and MacConkey agar. The 47(65.2%) E. coli isolates were confirmed using standard biochemical tests for E. coli. The results indicate the frequencies of Sat gene was 27 strains(57.5%) while Vat gene was 12 strains (25.5%) while the Duplex PCR detected 8(17%) strains of E. coli contained two genes. With this method, we confirmed that autotransporter genes are pathospecifically distributed among the E. coli strains studied.   http://dx.doi.org/10.25130/tjps.23.2018.167

scholarly journals Selective Isolation of eae-Positive Strains of Shiga Toxin-Producing Escherichia coli

2000 ◽  
Vol 38 (4) ◽  
pp. 1684-1687 ◽  
Author(s):  
Hiroshi Fukushima ◽  
Ken Hoshina ◽  
Manabu Gomyoda
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Acid Resistance ◽  
Selective Isolation ◽  
Macconkey Agar ◽  
Tellurite Resistance ◽  
E Coli

Culture on cefixime, tellurite, and sorbitol-MacConkey agar after HCl treatment facilitated the growth of 410 (94%) of 436eae-positive Shiga toxin-producing Escherichia coli (STEC) strains and 17 (16%) of 107 eae-negative STEC strains. This selectivity was closely related to acid resistance in E. coli and tellurite resistance ineae-positive STEC strains.

Efficacy of Chromocult Coliform Agar for Coliform and Escherichia coli Detection in Foods

2000 ◽  
Vol 63 (4) ◽  
pp. 539-541 ◽  
Author(s):  
K. M. TURNER ◽  
L. RESTAINO ◽  
E. W. FRAMPTON
Keyword(s):  
Escherichia Coli ◽  
Linear Relationship ◽  
Brilliant Green ◽  
Meat Products ◽  
Correlation Coefficients ◽  
Lauryl Sulfate ◽  
Regression Analyses ◽  
Positive Linear Relationship ◽  
E Coli ◽  
Final Confirmation

Chromocult coliform agar (CCA) was compared with Petrifilm Escherichia coli count plate (PEC) for identifying coliforms and E. coli in a variety of meat products. Products examined included 45 raw beef samples, 12 sausage emulsion samples, 11 samples of meat-based ready-to-eat appetizers, and 8 pork trimming samples. Coliforms from CCA and PEC were confirmed by gassing in brilliant green lactose broth plus a positive reaction on purple broth agar plus lactose after incubation at 35°C for 48 h. Lauryl sulfate tryptose plus methylumbelliferyl-β-glucuronide and tryptophan broth were used to confirm E. coli from CCA and PEC with 48-h incubations at 35 and 42.5°C, respectively. API 20E test strips were inoculated for final confirmation. The overall respective confirmation percentages (CFU/g) for the PEC and the CCA methods were 93.1 and 93.7% for coliforms and 99.8 and 98.1% for E. coli, although the CCA method yielded significantly (P < 0.001) higher mean CFU/g values for both coliforms and E. coli. Regression analyses of these data indicated a strong positive linear relationship existed between the two methods over a wide CFU/g range for both coliforms and E. coli. The respective correlation coefficients obtained for coliforms and E. coli of 0.89 and 0.86 indicate that the CCA method provides a reliable optional method for these determinations in meat products.

Molecular Characteristics Ecology Zoonotic Potential of Escherichia coli Strains that Cause Hemorrhagic Pneumonia in Animals

2021 ◽  
Author(s):  
Meghan E. G. Moore ◽  
Geisa Paulin-Curlee ◽  
Brian D. Johnston ◽  
Connie Clabots ◽  
Chitrita DebRoy ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Narrow Range ◽  
Clinical Manifestations ◽  
Clinical Isolates ◽  
Future Research ◽  
Molecular Characteristics ◽  
E Coli ◽  
Hemorrhagic Pneumonia ◽  
Cytotoxic Necrotizing Factor 1

Hemorrhagic pneumonia (HP) is a rare but highly lethal disease, mainly of dogs and cats, caused by hemolytic Escherichia coli strains that contain cnf1 (encoding cytotoxic necrotizing factor 1). After encountering fatal HP in two dogs, we used contemporary molecular methods, including multi-locus sequence typing and whole genome sequencing, to compare the corresponding case isolates with published HP clinical isolates and newly-obtained fecal E. coli isolates from 20 humans and animals in the index HP case household. We also compared the aggregated HP clinical isolates, which represented 13 discrete strains, by pulsotype with a large, private pulsotype library of diverse-source E. coli . The HP clinical isolates represented a narrow range of phylogenetic group B2 lineages (mainly sequence types 12 and 127), O types (mainly O4 and O6), and H types (mainly H5 and H31), but diverse fimH alleles (type-1 fimbriae adhesin). Their extensive, highly conserved virulence genotypes, which qualified as extraintestinal pathogenic E. coli (ExPEC), encoded diverse adhesins, toxins, iron uptake systems, and protectins. Household surveillance identified multiple HP-like fecal strains, plus abundant between-host strain sharing, including of the household's index HP strain. The pulsotype library search identified, for five HP clinical strains, same-pulsotype human and animal fecal and clinical (predominantly urine) isolates, from diverse locales and time periods. Thus, E. coli strains that cause HP derive from a narrow range of ExPEC lineages within phylogroup B2, contain multiple virulence genes other than cnf1 , are shared extensively between hosts, and likely function in nature mainly as intestinal colonizers and uropathogens. Importance This study clarifies the clonal background and extensive virulence genotypes of the E. coli strains that cause hemorrhagic pneumonia in domestic animals (mainly dogs and cats), shows that such strains circulate among animals and humans, identifies a substantial intestinal colonization component to their lifestyle, and extends their known clinical manifestations to include bacteremia and urinary tract infection. The findings place these strains better into context vis-a-vis current understandings of E. coli phylogeny, ecology, and pathogenesis; identify questions for future research; and may prove relevant for surveillance and prevention efforts.

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