• Journal of Microbiology
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• v.38 no.2
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• pp.93-98
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• 2000

Nine hundred patients diagnosed with diarrhea or hemorrhagic uremic syndrome in the Kyungpook Province, Korea, were examined from November 1998 to February 2000. One patient in Kumi appeared to possess the Escherichia coli O157:H7 strain, which is very important in clinical decision making and public health action. The isolated strain, an E. coli O157:H7 KM, contained a 60 MDa plasmid and typical virulence genes including the verotoxin 2 gene, ehxA gene (encoding enterohemorrhagic hemolysin), and eae (encoding attaching and effacing protein-intimin) gene. This strain produced only verotoxin 2. Pulsed field gel electrophoretic analysis showed that the genomic organization of the E. coli O157:H7 KM strain may differ greatly from those of representative strains previously reported in the United States and Japan.

• Childhood Kidney Diseases
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• v.10 no.2
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• pp.249-256
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• 2006

Diarrhea-associated hemolytic uremic syndrome(D+ HUS) is induced by enterohemorrhagic Escherichia coli(EHEC) and is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. The disease is usually transmitted by meat and water contaminated by excreta of domestic animals. We report a son and his mother with diarrhea-associated hemolytic uremic syndrome that spread within the family.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.130-136
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• 2021

Persister cell formation and biofilms of pathogens are extensively involved in the development of chronic infectious diseases. Eradicating persister cells is challenging, owing to their tolerance to conventional antibiotics, which cannot kill cells in a metabolically dormant state. A high frequency of persisters in biofilms makes inactivating biofilm cells more difficult, because the biofilm matrix inhibits antibiotic penetration. Fatty acids may be promising candidates as antipersister or antibiofilm agents, because some fatty acids exhibit antimicrobial effects. We previously reported that fatty acid ethyl esters effectively inhibit Escherichia coli persister formation by regulating an antitoxin. In this study, we screened a fatty acid library consisting of 65 different fatty acid molecules for altered persister formation. We found that undecanoic acid, lauric acid, and N-tridecanoic acid inhibited E. coli BW25113 persister cell formation by 25-, 58-, and 44-fold, respectively. Similarly, these fatty acids repressed persisters of enterohemorrhagic E. coli EDL933. These fatty acids were all medium-chain saturated forms. Furthermore, the fatty acids repressed Enterohemorrhagic E. coli (EHEC) biofilm formation (for example, by 8-fold for lauric acid) without having antimicrobial activity. This study demonstrates that medium-chain saturated fatty acids can serve as antipersister and antibiofilm agents that may be applied to treat bacterial infections.

• Journal of Preventive Medicine and Public Health
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• v.36 no.1
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• pp.77-84
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• 2003

Objectives : Two related cases of Hemolytic-Uremic Syndrome (HUS) were reported to the Korea National Institute of Health in May, 2001. Shiga toxin 2 genes were detected in both stool samples. We suspected an enterohemorrhagic Escherichia coli (EHEC) infection as the cause of the HUS, and conducted an investigation to find the source of the infection and its route of transmission. Methods : We peformed case investigations on these two related HUS cases, and obtained interviews and rectal swabs form the family members and other close contacts. Additionally, we peformed rectal swabs on the cattle raised by the household of the index patient. Results : We found a 20 month old index patient and a 6 year-old cousin had developed HUS, where there had been a 2 day history of contact with the index, and bacteriological examinations for these two patients revealed, indistinguishably, the same E. coli O171. The grandmother of the index patient was found to be asymptomatic, but E. coli O26 was isolated. We also found a probable case in the mother of the cousin. She reported a history of contact with the index, and developed bloody diarrhea of 3 days duration. The test results for the cattle revealed E. coli O26 in one cow, and E. coli O26 and O55 in another. E. coli O26, which was isolated in both cows and the grandmother of the index, were indistinguishably the same. Conclusions : We found that the E. coli O26 in the grandmother had originated from the cows, and that the E. coli O171 found in the index patient had been transmitted to the cousin through person-to-person contact.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.5-14
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• 2010

Enterohemorrhagic Escherichia coli O157:H7 is a major foodborne pathogen causing severe disease in humans worldwide. Healthy cattle are a reservoir of E. coli O157:H7, and bovine food products and fresh produce contaminated with bovine waste are the most common sources for disease outbreaks in the United States. E. coli O157:H7 also survives well in the environment. The abilities to cause human disease, colonize the bovine gastrointestinal tract, and survive in the environment require that E. coli O157:H7 adapt to a wide variety of conditions. Three major virulence factors of E. coli O157:H7 have been identified including Shiga toxins, products of the pathogenicity island called the locus of enterocyte effacement, and products of the F-like plasmid pO157. Among these virulence factors, the role of pO157 is least understood. This review provides a board overview of E. coli O157:H7 with an emphasis on pO157.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1238-1243
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• 2009

The susceptibilities of major enterohemorrhagic Escherichia coli (EHEC) strains to antimicrobial agents and the cytotoxicity of these agents were examined using a total of 38 strains of E. coli O26, O111, and O157, which are the major serogroups of EHEC. Among the 38 strains, 35, 36, and 36 were susceptible to amikacin, imipenem, and norfloxacin, respectively. These antimicrobial agents were further examined to determine their cytotoxicity on Vero cells as well as their effect on the release of Shiga toxins along with trimethoprim/sulfamethoxazole. Each of the E. coli O26, O111, and O157 strains containing both the stx1 and stx2 genes were grown in the absence or presence of these agents at 1/4 minimal inhibitory concentration for 6 h, 12 h, and 18 h. At the concentrations used in this study, none of the agents significantly altered cell count compared with the control group. The level of cytotoxicity in the imipenem group was lower at 12 hand 18 h than their respective controls. In contrast, the level of cytotoxicity in cultures treated with trimethoprim/sulfamethoxazole, norfloxacin, and amikacin was increased. The strains were also examined for the release of Shiga toxins 1 and 2 following treatment with the agents, which were measured by the reversed passive latex agglutination (RPLA) method. The RPLA assay showed a suppression of release of Shiga toxin 2 in the strain cultures containing imipenem. These results indicate that imipenem may be a safe and effective agent for inhibition of these bacteria, which has clinical implications for the treatment of EHEC infections.

• Biomedical Science Letters
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• v.4 no.1
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• pp.43-56
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• 1998

A multiplex PCR method was designed by employing primers specific for the eaeA gene, conserved sequences of Shiga-like toxins (SLT-I.II), and the 60-MDa plasmid of enterohemorrhagic E. coli (EHEC) O157:H7 strain. A set of six synthetic oligonucleotide primers derived from sequences of the SLT-I.II, eaeA, and 60-MDa plasmid genes of E. coli O157:H7 were used in a multiplex PCR amplification procedure to detect these genes in the same enteric pathogens. In two enterohemorrhagic E. coli O157:H7 (ATCC 35150, ATCC 43894) reference strains, PCR products of 317bps (eaeA), 228bps (SLT-I.II), and 167bps (60-MDa plasmid) were successfully amplified simultaneously in a single reaction. However, the specific PCR products were not amplified in control strains of other enteric bacteria. The sensitivity of the multiplex PCR assay for detection of the SLT-I.II, eaeA, and 60-MDa plasmid genes of E. coli O157:H7 was found to be 2.5$\times$10$^{6}$ of bacteria in diarrheal stool to amplify all three bands. The multiplex PCR technology will allow large-scale screening of many clinical specimens or contaminated foods, and will be a very useful method for the detection of a wide range of microorganisms present in the environment, including EHEC O157:H7 in various types of specimens. The multiplex PCR assay has the potential to be used as a specific and rapid method for clinical diagnosis of disease caused by EHEC O157:H7.

• Microbiology and Biotechnology Letters
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• v.50 no.4
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• pp.441-456
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• 2022

Shiga toxins (Stxs) are major virulence factors from the enterohemorrhagic Escherichia coli (EHEC), a subset of Stx-producing Escherichia coli. Stxs are multi-functional, ribosome-inactivating proteins that underpin the development of hemolytic uremic syndrome (HUS) and central nervous system (CNS) damage. Currently, therapeutic options for the treatment of diseases caused by Stxs are limited and unsatisfactory. Furthermore, the pathophysiological mechanisms underpinning toxin-induced inflammation remain unclear. Numerous works have demonstrated that the various host ribotoxic stress-induced targets including p38 mitogen-activated protein kinase, its downstream substrate Mitogen-activated protein kinase-activated protein kinase 2, and apoptotic signaling via ER-stress sensors are activated in many different susceptible cell types following the regular retrograde transportation of the Stxs, eventually leading to disturbing intercellular communication. Therapeutic options targeting host cellular pathways induced by Stxs may represent a promising strategy for intervention in Stx-mediated acute renal dysfunction, retinal damage, and CNS damage. This review aims at fostering an in-depth understanding of EHEC Stxs-mediated pathogenesis through the toxin-host interactions.

• Korean Journal of Food Science and Technology
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• v.48 no.4
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• pp.323-328
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• 2016

In this study, specific and rapid enrichment and growth conditions for the most important, classic non-O157 enterohemorrhagic Escherichia coli (EHEC) serogroups were assessed. Three enrichment broth types, namely, EC medium with MUG broth, BRILA broth, and mTSB broth with novobiocin, were compared to identify the optimum enrichment broth for EHEC isolation. Four kinds of selective media, namely, ENDO agar, Chromocult agar, TBX agar, and CHROMagar$^{TM}$ STEC medium, were compared to identify the optimum one for non-O157 EHEC isolation. The results suggested that incubation in EC medium with MUG broth at $42^{\circ}C$ for 20 h is optimum for the enrichment of non-O157 EHEC. TBX agar was identified to have the highest specificity among the tested media. Consequently, a combination of complementary selective media according to serotype must be considered for comprehensive isolation of specific EHEC.

• Korean Journal of Food Science and Technology
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• v.53 no.5
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• pp.657-668
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• 2021

We prepared the growth and survival models of enterohemorrhagic Escherichia coli (EHEC) and Campylobacter jejuni in milk as a function of temperature and assessed the microbiological risks associated with the consumption of whole milk. EHEC and C. jejuni were not detected in whole milk (n=195) in the retail market. The minimum growth temperature of EHEC in milk was 7℃. The lag time of EHEC in whole milk was longer than that in skim milk. The survival ability of C. jejuni in milk was better at 4℃ than at 10℃. Lower delta values were observed in whole milk than in skim milk, indicating that C. jejuni survived better in skim milk. The probability of foodborne illness from whole milk consumption was 5.70×10^-5 for EHEC and 9.86×10^-9 for C. jejuni. Sensitivity analysis results show that the market temperature of EHEC and the dose-response model of C. jejuni are correlated with the probability of foodborne illness.