• Journal of Veterinary Science
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• v.23 no.2
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• pp.28.1-28.18
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• 2022

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea in developing countries. However, sporadic outbreaks caused by this microorganism in developed countries are frequently reported recently. As an important zoonotic pathogen, EPEC is being monitored annually in several countries. Hallmark of EPEC infection is formation of attaching and effacing (A/E) lesions on the small intestine. To establish A/E lesions during a gastrointestinal tract (GIT) infeciton, EPEC must thrive in diverse GIT environments. A variety of stress responses by EPEC have been reported. These responses play significant roles in helping E. coli pass through GIT environments and establishing E. coli infection. Stringent response is one of those responses. It is mediated by guanosine tetraphosphate. Interestingly, previous studies have demonstrated that stringent response is a universal virulence regulatory mechanism present in many bacterial pathogens including EPEC. However, biological signficance of a bacterial stringent response in both EPEC and its interaction with the host during a GIT infection is unclear. It needs to be elucidated to broaden our insight to EPEC pathogenesis. In this review, diverse responses, including stringent response, of EPEC during a GIT infection are discussed to provide a new insight into EPEC pathophysiology in the GIT.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1191-1199
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• 2021

Enteropathogenic Escherichia coli (EPEC), which belongs to the attaching and effacing diarrheagenic E. coli strains, is a major causative agent of life-threatening diarrhea in infants in developing countries. Most EPEC isolates correspond to certain O serotypes; however, many strains are non-typeable. Two EPEC strains, EPEC001 and EPEC080, which could not be serotyped during routine detection, were isolated. In this study, we conducted an in-depth characterization of their putative O-antigen gene clusters (O-AGCs) and also performed constructed mutagenesis of the O-AGCs for functional analysis of O-antigen (OAg) synthesis. Sequence analysis revealed that the occurrence of O-AGCs in EPEC001 and E. coli O132 may be mediated by recombination between them, and EPEC080 and E. coli O2/O50 might acquire each O-AGC from uncommon ancestors. We also indicated that OAg-knockout bacteria were highly adhesive in vitro, except for the EPEC001 wzy derivative, whose adherent capability was less than that of its wild-type strain, providing direct evidence that OAg plays a key role in EPEC pathogenesis. Together, we identified two EPEC O serotypes in silico and experimentally, and we also studied the adherent capabilities of their OAgs, which highlighted the fundamental and pathogenic role of OAg in EPEC.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.125-130
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• 1987

The role of enteropathogenic Escherichia coli(EPEC) was evaluated in a group of children with endemic diarrhea admitted to Hanyang University Hospital in Seoul, Korea. EPEC was detected in fecal samples of 23% of 100 cases and 4.5% of 44 concurrent control children. The most commonly isolated EPBC strains were serogroups $O_{18a}O_{18c}:K_{77},\;O_{86a}:K_{61},\;O_{119}:K_{69},\;and\;O_{128}:K_{70}$. On testing for enterotoxin production, 6(26%) strains were isolated from 17% of the 100 diarrheal children and in 4.5% of the 44 well controls(P<0.05). Our study supports the concept that EPEC may be an important cause of endemic diarrheas in Korea.

• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.328-336
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• 2022

Aptamers are short, chemically synthesized, single-stranded DNA or RNA oligonucleotides that fold into unique three-dimensional structures. In this study, we aim to determine the antibiofilm activity and binding specificity of the six polyclonal DNA aptamers (S15K3, S15K4, S15K6, S15K13, S15K15, and S15K20) on Staphylococcus aureus BPA-12 and Escherichia coli EPEC 4. Aptamer S15K6 showed the highest percentage of antibiofilm activity against S. aureus BPA-12 (37.4%) as shown by the lowest OD570 value of 0.313. Aptamer S15K20 showed the highest percentage of antibiofilm activity against E. coli EPEC 4 (15.4%) as shown by the lowest OD570 value of 0.515. Aptamers S15K13 and S15K20 showed antibiofilm activities against both S. aureus BPA-12 and E. coli EPEC4, and thus potentially have broad reactivity. Furthermore, based on the binding capacity and Kd values from our previous study, the binding specificity assay of selected polyclonal DNA aptamers (S15K3 and S15K15) against S. aureus BPA-12, E. coli EPEC 4, S. aureus BPA-6, S. agalactiae, E. coli MHA-6, and Listeria monocytogenes were performed using qPCR. Aptamers S15K3 and S15K15 showed specific binding to S. aureus BPA-12, E. coli EPEC 4, S. aureus BPA-6, and S. agalactiae, but could not bind to E. coli MHA-6 and L. monocytogenes. Therefore, this study showed that the polyclonal DNA aptamers have antibiofilm activity and were able to bind to S. aureus BPA-12 and E. coli EPEC 4 bacteria.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.525-529
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• 2009

Cytolethal distending toxins (CDTs) represent an emerging family of newly described bacterial products that are produced by a number of pathogens. The genes encoding these toxins have been identified as a cluster of three adjacent genes, cdtA, cdtB, and cdtC, plus 5 cdt genetic variants, designated as cdt-I, cdt-II, cdt-III, cdt-IV, and cdt-V, have been identified to date. In this study, a general multiplex PCR system designed to detect Escherichia coli cdts was applied to investigate the presence of cdt genes among isolates. As a result, among 366 E. coli strains, 2.7% were found to carry the cdtB gene. In addition, the use of type-specific primers revealed the presence of cdt-I, cdtIV, and cdt-V types of the cdt gene, yet no cdt-II or cdt-III strains. The presence of other virulence genes (stxl, stx2, eae, bfp, espA, espB, and espD) was also investigated using a PCR assay. Among the 10 cdtB gene-positive strains, 8 were identified as COT-producing typical enteropathogenic E. coli (EPEC) strains ($eae^+$, $bfp^+$), whereas 2 were identified as CDT-producing atypical EPEC strains ($eae^+$, $bfp^-$). When comparing the cytotoxic activity of the CDT-producing typical and atypical EPEC strains, the CDT-producing atypical EPEC strains appeared to be less toxic than the CDT-producing typical EPEC strains.

• Biomedical Science Letters
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• v.24 no.1
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• pp.1-8
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• 2018

${\mu}MT$ knockout mice are genetically deficient in the transmembrane domain of mu chain of the immunoglobulin M (IgM) heavy chain, resulting in the absence of mature B cells. ${\mu}MT$ knockout mice is an in vivo model system used to clarify the role of B cells in various diseases. Enteropathogenic Escherichia coli (EPEC) induces acute and chronic diarrheal disease, especially in children of developing countries. The formation of attaching and effacing (A/E) lesion is a prominent pathogenic factor in the intestinal epithelium of EPEC infection. The A/E lesion is modulated by genes located on the pathogenic island locus of enterocyte effacement (LEE) which encode a type III secretion system (T3SS) and A/E lesion-related effector proteins. Citrobacter rodentium is a murine pathogen utilized in studying the pathogenic mechanisms of EPEC in human infections. Citrobacter rodentium produce A/E lesion to attach to intestinal epithelium, thus providing a murine model pathogen to study EPEC. Several studies have investigated the pathogenesis of Citrobacter rodentium in the ${\mu}MT$ knockout mice. In this review, we introduce the ${\mu}MT$ murine model in the context of C. rodentium pathogenesis and describe in detail the role of B cells and antibodies in this disease.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.525-531
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• 2020

Objectives: This study was performed to identify the epidemiological features of a food poisoning outbreak in a company cafeteria located in Chungcheongnam-do Province, Korea in June of 2020 and to suggest preventive measures for a similar incidence. Methods: A total of 84 patients with acute gastroenteritis were examined. Environmental samples were obtained from 16 food handlers, six food utensils, 135 preserved foods served over three days and nine menus, and six drinking water samples. These are analyzed to detect viruses and bacteria. Results: Ninety-four out of the 402 people who were served meals (23.4%) predominantly showed symptoms of diarrhea, and the number was over 3 times. Among the 84 patients under investigation, 17 cases (20.2%) were positive for Enteropathogenic E. coli (EPEC) and 18 cases were positive for Clostridium (C.) perfringens (21.4%). Based on the investigation, it was concluded that the main pathogens were EPEC and C. perfringens. For EPEC, it was detected in three of the food service employees and in the preserved food and curry rice. The results of pulsed field gel electrophoresis indicate that all EPEC cases are closely related except for one food service employee. Assuming that isolated EPEC originated from the preserved food, the incubation period is about 25 hours. The origin of the C. perfringens was not determined as it was not detected in the food service employees or environmental samples. Conclusions: This case suggests that food provided in group food service centers must be thoroughly managed. In addition, identifying the pathogens in preserved food is very important for tracing the causes of food poisoning, so food must be preserved in an appropriate condition. To prevent similar food poisoning cases, analyzing cases based on epidemiological investigation and sharing the results is needed.

• 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.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2003.10a
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• pp.30-30
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• 2003

Escherichia coli strains associated with diarrhea have been divided into the following six major categories on the basis of pathogenic mechanisms: enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), enteroaggregative E. coli (EAggEC) and diffusely adherent E. coli (DAEC).$\^$15,18/ EPEC, EAggEC, and DAEC strains were classified by their ability to produce distinct patterns of adherence to cultured epithelial cells in virto: localized (LA), aggregative (AA), and diffuse (DA) adherence. The objective of this study was to investigate the relationship of the adherence patterns with AIDA-positive E. coli isolated from diarrheic pigs. (omitted)

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.862-868
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• 2014

Certain Escherichia coli (E. coli) strains have the ability to cause diarrheal disease. Five types of diarrheagenic E. coli have been identified, including EHEC, ETEC, EPEC, EAEC, and EIEC. To detect these five diarrheagenic types rapidly, we developed a one-step multiplex PCR (MP-PCR) assay using nine primer pairs to amplify nine virulence genes specific to the different virotypes, with each group being represented (i.e., stx1 and stx2 for EHEC, lt, sth, and stp for ETEC, eaeA and bfpA for EPEC, aggR for EAEC, and ipaH for EIEC). The PCR primers were constructed using MultAlin. The sensitivity and specificity of the constructed multiplex PCR primers were measured using DNA isolated from diarrheagenic E. coli strains representing each group. The limits of detection were as follows: $5{\times}10^1CFU/ml$ for EHEC, $5{\times}10^3CFU/ml$ for ETEC expressing lt and sth, $5{\times}10^4CFU/ml$ for ETEC expressing stp, $5{\times}10^2CFU/ml$ for EPEC, $5{\times}10^4CFU/ml$ for EAEC, and $5{\times}10^2CFU/ml$ for EIEC. To confirm the specificity, C. jejuni, C. perfringens, S. Typhimurium, V. parahaemolyticus, L. monocytogenes, Y. enterocolitica, B. cereus, and S. aureus were used as negative controls, and no amplification was obtained for these. Moreover, this kit was validated using 100 fecal samples from patients with diarrhea and 150 diarrheagenic E. coli strains isolated in Korea. In conclusion, the multiplex PCR assay developed in this study is very useful for the rapid and specific detection of five diarrheagenic E. coli types. This single-step assay will be useful as a rapid and economical method, as it reduces the cost and time required for the identification of diarrheagenic E. coli.