DNA HYBRIDIZATION METHOD FOR DETECTING ENTEROTOXIGENIC ESCHERICHIA COLI IN HUMAN ISOLATES AND ITS POSSIBLE APPLICATION TO FOOD SAMPLES

1981 ◽  
Vol 3 (4) ◽  
pp. 233-247 ◽  
Author(s):  
WALTER E. HILL
Keyword(s):  
Escherichia Coli ◽  
Dna Hybridization ◽  
Food Samples ◽  
Enterotoxigenic Escherichia Coli ◽  
Hybridization Method

Increased Reliability in Detection of Enterotoxigenic Escherichia coli by DNA Colony Hybridization1

1987 ◽  
Vol 50 (6) ◽  
pp. 487-489 ◽  
Author(s):  
VALERIE MITCHELL DAVIS
Keyword(s):  
Escherichia Coli ◽  
Dna Hybridization ◽  
False Negative ◽  
Enterotoxigenic Escherichia Coli ◽  
Hybridization Method ◽  
X Ray ◽  
Genes Encoding ◽  
Autoradiographic Analysis ◽  
Labeled Probe ◽  
Pathogenic Determinant

Previously a DNA hybridization assay was designed to detect the presence of and to enumerate enterotoxigenic foodborne Escherichia coli. The determinative step in the method involves autoradiographic analysis of the DNA from foodborne isolates after hybridization with a 32P-labeled probe specific for an enterotoxin gene. Dark spots appearing on the X-ray film after exposure indicate which colonies carry genes encoding the pathogenic determinant. A problem with this assay is the tendency of some colonies to detach from the nitrocellulose filters during hybridization or washing to remove the unbound probe DNA; this results in a false-negative interpretation in up to 60% of the samples processed at 80°C. By lowering the temperature to 70°C and increasing the incubation time to 3 h during in vacuo baking of filters, detachment (flotation) of colonies is reduced to about 37%. At 65°C only 2% of the colonies came off the filter after in vacuo baking of filters for 24 h. Another problem has been the inadequacy of exposure of X-ray film at −20°C when a −70°C freezer is not available. This problem can be alleviated by exposing the X-ray film in cassette holders “sandwiched” between slabs of dry ice (CO2 ice has a temperature of −78.5°C). These modifications improve the reliability and accuracy of this DNA colony hybridization method.

scholarly journals Outbreak of CTX-M-15-Producing Enterotoxigenic Escherichia coli O159:H20 in the Republic of Korea in 2016

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Jin Seok Kim ◽  
Jungsun Park ◽  
Eunkyung Shin ◽  
Soojin Kim ◽  
Sung Suck Oh ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High School ◽  
Food Samples ◽  
Enterotoxigenic Escherichia Coli ◽  
Republic Of Korea ◽  
Third Generation ◽  
Content Type ◽  
The Republic ◽  
Third Generation Cephalosporins

ABSTRACT We investigated an outbreak of enterotoxigenic Escherichia coli (ETEC) O159:H20 associated with the consumption of a tossed-noodle dish in a high school in 2016. Thirty-three ETEC strains isolated from clinical and food samples were genetically indistinguishable. The outbreak strains were resistant to third-generation cephalosporins and harbored a bla CTX-M-15 gene on a 97-kb self-transferable IncK plasmid. This is the first outbreak caused by CTX-M-15-producing ETEC strains.

scholarly journals Comparison of virulence markers and antibiotic resistance in enterotoxigenic Escherichia coli isolated ten years apart in Tehran

2010 ◽  
Vol 5 (04) ◽  
pp. 248-254 ◽  
Author(s):  
Nader Shahrokhi ◽  
Saeid Bouzari ◽  
Anis Jafari
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Dna Hybridization ◽  
Pathogenic Bacteria ◽  
Enterotoxigenic Escherichia Coli ◽  
Significant Shift ◽  
Bacterial Populations ◽  
Virulence Markers ◽  
Class 1 ◽  
Resistance Patterns

Introduction: Enterotoxigenic Escherichia coli (ETEC) causes diarrhoea by producing heat-labile (LT) or heat-stable (ST) enterotoxins after colonizing the small intestine by means of colonization factors (CFs). Although detection of the toxins is sufficient for verification of ETEC isolates, toxin-positive strains may be further analyzed for the presence of CFs. Antibiotics may shorten the duration of diarrhoea caused by ETEC, but the rapid emergence of resistant strains limits their usefulness. Methodology: ETEC isolates collected 10 years apart were compared for the prevalence of toxin types, CFs and antibiotic resistance. DNA/DNA hybridization with digoxigenin (DIG)-labeled probes was used for the detection of toxin types, and CF-typing was performed by DNA hybridization using DIG-labeled probes for cfaD and CS6 with slide agglutination. Disk diffusion was used to determine antibiotic resistance. The presence of class 1 integrons was detected by PCR. Results: ST-positive isolates were the most prevalent among the isolates from 1988, but a significant shift towards LT-gene carriage was observed in the 1998 group. CFA/I and CFA/IV were the most common CF types within both groups. The most prevalent resistance patterns among these isolates were ACSTSXT followed by ASTSXT and ASSXT. Conclusion: Our study of the two groups of isolates showed that the rate of LT and ST gene carriage, as well as antibiotic resistance markers, has changed in the ten years separating the two bacterial populations. These variations show the importance of monitoring pathogenic bacteria to obtain a near realistic picture of the circulating bacterial pathogens.

Identification by DNA Hybridization of Enterotoxigenic Escherichia coli in a Longitudinal Study of Villages in Thailand

1985 ◽  
Vol 151 (1) ◽  
pp. 124-130 ◽  
Author(s):  
P. Echeverria ◽  
J. Seriwatana ◽  
D. N. Taylor ◽  
C. Tirapat ◽  
W. Chaicumpa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Longitudinal Study ◽  
Dna Hybridization ◽  
Enterotoxigenic Escherichia Coli

Enterotoxigenic Escherichia coli Isolated from Foods in São Paulo, Brazil

1987 ◽  
Vol 50 (10) ◽  
pp. 832-834 ◽  
Author(s):  
BERNADETTE D. G. M. FRANCO ◽  
BEATRIZ E. C. GUTH ◽  
LUIZ R. TRABULSI
Keyword(s):  
Escherichia Coli ◽  
Food Samples ◽  
Sao Paulo ◽  
Enterotoxigenic Escherichia Coli ◽  
São Paulo ◽  
E Coli ◽  
Colonization Factors ◽  
The City

Incidence of enterotoxigenic Escherichia coli (ETEC) in foods usually consumed in the city of Sao Paulo, Brazil was determined. Raw and cooked foods of animal and vegetable origin were investigated. Enterotoxigenic strains were found in approximately 3.5% of food samples contaminated with E. coli. There was a great predominance of ETEC strains producing only LT enterotoxin. None of the isolated strains produced LT and ST simultaneously. Several serotypes were involved, and none of them was positive for colonization factors CFA-I and CFA-II. One ETEC showed resistance to some antibiotics but most were sensitive to the ones tested.

scholarly journals Prevalence of enteropathogenic and enterotoxigenic Escherichia Coli in foods of animal origin in southern Brazil

1996 ◽  
Vol 26 (2) ◽  
pp. 247-250 ◽  
Author(s):  
José Antonio Aleixo ◽  
Gladis Paim Aver
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Food Samples ◽  
Enterotoxigenic Escherichia Coli ◽  
Animal Origin ◽  
Resistance Pattern ◽  
Southern Brazil ◽  
E Coli ◽  
Highly Sensitive ◽  
The City

Prevalence of Escherichia coli in foods of animal origin from the city of Pelotas, Brazil, was determined. The ocurrence of enterotoxigenic (ETEC) and classic enteropathogenic (EPEC) serogroups among E. coli isolates was determined. E. coli was isolated from 68% of the food samples surveyed. Of 36 food samples tested, 11(30%) and 24(66%) were positive for EPEC and ETEC strains respectively. However, of 187 E. coli isolates tested, 30(16%) were EPEC compared to 75(40%) which were ETEC. The antibiotic resistance pattern revealed that the isolates were highly sensitive to all antibiotics tested.

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