• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.147-153
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• 1987

Colonization factor antigen I(CFA I) has been shown to be one of several virulence factors that promote attachment of enterotoxigenic E. coli(ETEC) to small intestinal epithelial cells of humans. The ability of ETEC to produce mannose-resistant hemagglutination(MRHA) of human blood group A has been used to detect CFA I. To determine gastrointestinal carriage in Korean children of E. coli with MRHA and CFA I, 116 strains of E. coli from diarrheal children admitted to Hanyang University Hospital were examined for MRHA of human erythrocytes and the presence of CFA I. Of 45 ETEC strains, 18(40%) gave a positive MRHA($MRHA^+$) and eight(18%) were positive for CFA I(CFA $I^+$). ETEC with CFA I were all heat-stable enterotoxin(ST) producers and two of these strains were of serogroups $O_{25}$. Of 17 classic enteropathogenic E. coli(EPEC), 7(41%) were $MRHA^+$ but all were negative for CFA I(CFA $I^-$). Of 30 enteroadherent E. coli(EAEC) strains, 11(37%) were $MRHA^+$ and one was CFA $I^+$. Of 24 nonpathogenic E. coli, 4(17%) were $MRHA^+$ but all were CFA $I^-$. It was shown that MRHA was common in all strains of E. coli, CFA I was limited only to ST producing ETEC and EAEC; although MRHA is a useful screening procedure, serologic tests seem to be necessary to comfirm CFA I production. CFA I was associated with a lower proportion of ETEC isolates in Korea than has been reported for other locations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.6
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• pp.875-880
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• 2012

This study was conducted to investigate the level of contamination of pathogenic Escherichia (E.) coli in 50 types of red pepper powders collected domestically. Pathogenic E. coli was confirmed using real-time PCR to confirm the 4 types of EAEC, EPEC, EHEC and ETEC. One sample out of 50 was contaminated with pathogenic E. coli. The type of pathogenic E. coli detected in the sample was EAEC. This study was also conducted to determine the effect of alcohol treatment on the reduction of E. coli populations in red pepper powder. The amount of E. coli in the control was $1.2{\times}10^6$ cfu/mL. The amount of E. coli in 10 minutes immersion treatment with 10% alcohol was $1.1{\times}10^6$ cfu/mL. In samples treated with over 20% alcohol, E. coli was not detected. This showed that 10 minutes of immersion in over 20% alcohol might be effective to reduce E. coli. This study was also conducted to determine the effect of UV irradiation on E. coli reduction. The number of E. coli in the control group was $5.0{\times}10^5$ cfu/mL. However, the number of E. coli in 45 min of the UV irradiated sample decreased to $1.0{\times}10^3$ cfu/mL, by $10^2$ cfu/mL. In contrast, E. coli was not detected in an over 60 min UV irradiated sample in $10^{-2}dilution$. This study showed that over 20% alcohol treatment and UV irradiation for 60 min was effective to control E. coli in red pepper powder.

• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.271-281
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• 2021

Pathogenic Escherichia coli (E. coli) is one among the most important agents of diarrhea in calves. From January to December 2021, 108 isolates from feces of calves with diarrhea were investigated for enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), shiga toxin-producing E. coli (STEC), enteroaggregative E. coli (EAEC), and enteroinvasive E. coli (EIEC) using real-time PCR. In addition, the genes for F5, F17 and F41 fimbriae were detected by PCR. The most frequently isolated pathotypes were EPEC/STEC (29 isolates), and ETEC/EPEC/STEC (29 isolates). ETEC/EPEC, and ETEC/STEC were also found in 10 isolates. EPEC, STEC, and ETEC were detected in 13, 11, and 6 respectively. EAEC, and EIEC was not detected. Antimicrobial resistance test was carried out by agar disc diffusion method with 14 antimicrobials. Among 108 pathogenic E. coli isolates, 107 isolates were resistant to at least one of 14 antibiotics used in this study, 99 (91.7%) were resistant to two or more antimicrobials, and a single remarkable isolate was resistant to 14 antimicrobials. The isolates were primarily resistant to penicillins, streptomycin, tetracycline, ceftiofur, Trimethoprim/sulfamethoxazole, Kanamycin, and Ciprofloxacin. The high rate of resistance in pathogenic E. coli, sometimes to multiple drugs, may complicate future options for treating human infections. These results may bu used for diagnosis and therpeitic purposes in calves with diarrhea.

• Journal of Dairy Science and Biotechnology
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• v.39 no.2
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• pp.51-62
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• 2021

Escherichia coli are the predominant facultative bacteria found in the gastrointestinal tract of animals and humans. Some strains of E. coli that acquire virulence factors and cause foodborne and waterborne diseases in humans are called pathogenic E. coli and can be divided into five pathotypes according to the virulence mechanism: EAEC, EHEC, EIEC, EPEC, and ETEC. Although selective media have been developed to detect E. coli, distinguishing pathogenic strains from non-pathogenic ones is difficult because of their similar biochemical properties. Therefore, it is very important to find a new and effective diagnostic method to identify pathogenic E. coli. With recent advances in molecular biology and whole genome sequencing, the use of polymerase chain reaction (PCR) is increasing rapidly. In this review paper, we provide an overview of pathogenic E. coli and present a review on PCR detection methods that can be used to diagnose pathogenic E. coli. In addition, the possibility of real-time PCR incorporating IAC is introduced. Consequently, this review paper will contribute to solving the current challenges related to the detection of pathogenic E. coli.

• Journal of Environmental Health Sciences
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• v.42 no.3
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• pp.189-195
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• 2016

Objectives: To ensure the microbiological safety of groundwater, it was confirmed whether waterborne pathogenic bacteria in groundwater samples tested positive for total coliforms in the Chungcheongnam-do Province region. Methods: Total colony counts, total coliforms and fecal coliforms were tested according to the process mandated by the drinking water quality testing standards of Korea. DNA was extracted from the samples, tested positive for total coliforms, and then subjected to real-time PCR to detect waterborne pathogenic bacteria. Results: A total of 115 samples were inadequate for drinking water. Thirty-one cases (27%) showed positive for fecal coliforms and nine cases (7.8%) showed total colony counts exceeding drinking water standards. Twenty-seven cases (23.5%) showed three items (total colony counts, total coliforms and fecal coliforms). Using the real-time PCR method, waterborne pathogens were detected in 57 cases (49.6%) in 115 samples. Seventy-eight cases of waterborne pathogenic bacteria were detected (including duplications): 27 cases of pathogenic E. coli (EPEC (19), ETEC (5), EHEC (1), EAEC (1) and EIEC (1)); 45 of Bacillus cereus; two of Yersinia spp.; two of Salmonella spp.; one of Staphylococcus aureus; one of Clostridium perfringens. Conclusion: The real-time PCR method can offer rapid and accurate detection of waterborne pathogenic bacteria. Therefore, this assay could be an alternative to conventional culture methods and can further ensure the microbiological safety of groundwater.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.285-295
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• 2014

This study was conducted to survey the epidemiological characteristics and the isolated strains for pathogenic E. coli which was the major causative organisms for food poisoning occurred at school food services in the Gyeonggi-do area during the past three years. We investigated 19 accidents of food-borne disease outbreaks by pathogenic E. coli at school food services from 2010 to 2012. Food-borne disease outbreaks by pathogenic E. coli were usually occurred at direct management type (18 accidents, 95%) and high schools. For the seasonal factors, 13 accidents (65%) were occurred in June to September, especially the end of August and September after the summer holidays. The first patients were occurred on Wednesday (7 accidents, 37%) and Thursday (7 accidents, 37%), and they were mainly reported on Thursday (7 accidents, 37%) and Friday (5 accidents, 26%). The exposure of risk was estimated in Monday (4 accidents, 21%), Tuesday (7 accidents, 37%) and Wednesday (4 accidents, 21%), and kimchi (5 accidents, 50%) was estimated as the food of the high risk responsible for the outbreaks. 98 isolates of pathogenic E. coli consisted of PEC (50%), ETEC (34%), EAEC (15%), and EHEC (1%). The antibiotic resistance of pathogenic E. coli showed in the descending order of ampicilline (40%), nalidixic acid (37%), trimethoprim/sulfamethoxazole (24%), and tetracycline (19%). The antibiotics of second and third generation cephalosporins, cabarpenem, aminoglycosides, and second generation quinolones had antimicrobial susceptibilities and cefalotin, ampicillin/sulbactam and chloramphenicol showed medium resistance at 29%, 25%, and 6% respectively, and 70% of isolates were resistant to more than one antibiotic. By the PFGE analysis, they were classified into nine major groups and 31 profiles with 57% pattern similarity. It was very difficult to find the correlation of antimicrobial susceptibilities and genotype in the small scale-food poisoning, but the similarity of antimicrobial resistance and PFGE patterns in the large scale-food poisoning enabled the outbreaks to estimate the same pathotype of E. coli derived from identical origins.

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.366-374
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• 2012

Recently pathogenic E. coli is one of the main foodborne pathogens resulting in many patients in Korea. To understand the characteristics of pathogenic E. coli outbreaks in Korea, the epidemiological investigation reports of pathogenic E. coli outbreak in 2009 (41 reports) and in 2010 (27 reports) were collected in the web site of the Korea Centers for Disease Control and Prevention, reviewed and analysed in this study. The main places of the pathogenic E. coli outbreaks were food catering service area (64.8%) and restaurants (25.0%). The main type of the pathogens were EPEC (44.7%) and ETEC (34.2%). EAEC and EHEC was responsible for 10.5 and 9.2%, respectively. Eight of 68 outbreak cases were caused by more than 2 types of pathogenic E. coli which implicates the complicated contamination pathways of pathogenic E. coli. The incidence rate of pathogenic E. coli was $33.6{\pm}30.5%$ and the main symptoms were diarrhea, stomach ache, nausea, vomiting, and fever etc. The two identified food sources were identified as frozen hamburger pattie and squid-vegetable mixture. To improve the food source identification by epidemiological investigation, food poisoning notification to the agency should not be delayed, whole food items attributed the outbreak should be collected and detection method of the various pathogenic E. coli in food has to be improved. In conclusion, the characteristics between the EHEC outbreaks in the western countries and the EPEC or ETEC outbreaks in Korea needs to be distinguished to prepare food safety management plan. In addition, the development of the trace back system to find the contamination pathway with the improved detection method in food and systemic and cooperative support by the related agencies are necessary.