• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.87-92
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• 2016

Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) which expresses F18 fimbriae and/or Stx type 2e (Stx2e). While STEC causes a severe illness including hemorrhagic colitis and hemolytic-uremic syndrome in humans, it induces damage to the vascular endothelium, which results in edema, hemorrhage, and microthrombosis, leading in high mortality in pigs. In the present study, we cultured Stx2e-producing E. coli field isolates from conventional pig farms that experienced sudden deaths previously with symptoms similar to porcine edema disease, which were further investigated with Shiga toxin profiles. A total of 43 strains were identified from the collected samples by F18 or Stx2e specific PCR. Based on the PCR, 42 isolates out of 43 isolates were proved to carry one of F18 or Stx2e genes and 14 isolates to carry both F18 and Stx2e genes. All of the 30 isolates that harbored Stx2e gene induced the cytopathic effect (CPE) in vero cells and especially, the isolate 150229 produced the highest level of Shiga toxin. Therefore, we identified the virulence genes (F18 and Stx2e) and demonstrated Shiga toxin-producing abilities from porcine edema disease causing E. coli filed isolates. These results suggested that one of the isolates could be a vaccine antigen candidate against STEC through further investigating to elicit an immune response.

• Korean Journal of Veterinary Research
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• v.46 no.2
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• pp.135-142
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• 2006

Shiga toxin (stx) producing Escherichia coli (STEC) causes various clinical signs in animal and human. In this study, 255 fecal samples from calves showing diarrhea were collected from cattle farms in Chonnam province during the period from January 2005 to July 2005. Twenty six STEC (10%) were isolated from 255 fecal samples by PCR. The isolates displayed three different stx combinations (stx1 [69%], stx1 and stx2 [15%], and stx2 [38%]). The isolates were further studied for virulence associated genes and antimicrobial resistance to define the virulence properties. Intimin (eaeA), enterohemolysin (hlyA), and lipopolysaccharide (rfbE) virulence genes were detected in 6 (23%), 7 (26%), and 1 (3.8%) of the isolates, respectively, by PCR. One isolate possessing rfbE gene was typed as E. coli 0157 : H7 by agglutination test with O and H antisera. All 26 isolates showed susceptibility to amikacin (100%) and the majority of isolates showed high susceptibility to gentamicin (88.5%) and chloramphenicol (73.1%). But all isolates were resistant to penicillin. These results may provide the basic knowledge to establish strategies for the treatment and prevention of enteric disease in calves.

• Korean Journal of Veterinary Service
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• v.32 no.3
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• pp.241-249
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• 2009

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains can cause broad spectrum of human disease, including diarrhea, hemorrhagic colitis, and the life-threatening hemolytic uremic colitis (HUS). We examined 868 samples was taken from bovine feces and carcass from January to December 2008 in Seoul. Twenty two (9.5%) shiga toxin -producing Escherichia coli were isolated from the 230 of bovine feces, and two (0.31%) were isolated from the 638 of carcasses. Serotype of E. coli isolates were O157 (10, 41.6%), O26 (10, 41.6%), O111 (1, 4.2%) and UT (3, 12.6%). In PCR, the isolates displayed three different stx gene combination (stx1 [2, 8.4%]), stx2 [3, 12.6%] and stx1 and stx2 [19,87.5%]). The eaeA and hlyA gene were found in 11 (45.8%) of the 24 strains. Saa gene was present only one strains (4.2%). Toxin typing using reverse passive latex agglutination test showed the same result in VT 1. But it showed different result in VT 2. In antimicrobial susceptibility test, all isolates were sensitive to amikacin, amoxicillin/clavulanic acid, ciprofloxacin and colistin. Eighteen strains (75.0%) of 24 isolates showed the multi-resistant patterns with over 3 drugs. PFGE was performed after the genomic DNA of twenty four isolates was digested with Xba I. the 24 isolates showed 7 (A~G) PFGE type.

• Journal of Microbiology and Biotechnology
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• v.25 no.9
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• pp.1460-1466
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• 2015

In this study, the prevalence of Shiga toxin-producing Escherichia coli (STEC) was investigated among raw meat or meat products from slaughterhouses and retail markets in South Korea, and their potential for antibiotic resistance and virulence was further analyzed. A total of 912 raw meats, including beef, pork, and chicken, were collected from 2008 to 2009. E. coli strains were frequently isolated in chicken meats (176/233, 75.9%), beef (102/217, 42.3%), and pork (109/235, 39.2%). Putative STEC isolates were further categorized, based on the presence or absence of the Shiga toxin (stx) genes, followed by standard O-serotyping. Polymerase chain reaction assays were used to detect the previously defined virulence genes in STEC, including Shiga toxins 1 and Shiga toxin 2 (stx1 and 2), enterohemolysin (ehxA), intimin (eaeA), STEC autoagglutination adhesion (saa), and subtilase cytotoxin (subAB). All carried both stx1 and eae genes, but none of them had the stx2, saa, or subAB genes. Six (50.0%) STEC isolates possessed the ehxA gene, which is known to be encoded by the 60-megadalton virulence plasmid. Our antibiogram profiling demonstrated that some STEC strains, particularly pork and chicken isolates, displayed a multiple drug-resistance phenotype. RPLA analysis revealed that all the stx1-positive STEC isolates produced Stx1 only at the undetectable level. Altogether, these results imply that the locus of enterocyte and effacement (LEE)-positive strains STEC are predominant among raw meats or meat products from slaughterhouses or retail markets in Korea.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.710-716
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• 2021

A risk analysis of Shiga toxin (Stx)-encoding bacteriophage was carried out by confirming the transduction phage to non-Stx-producing Escherichia coli (STEC) and subsequent expression of the Shiga toxin genes. The virulence factor stx1 was identified in five phages, and both stx1 and stx2 were found in four phages from a total of 19 phage isolates with seven non-O157 STEC strains. The four phages, designated as ϕNOEC41, ϕNOEC46, ϕNOEC47, and ϕNOEC49, belonged morphologically to the Myoviridae family. The stabilities of these phages to temperature, pH, ethanol, and NaClO were high with some variabilities among the phages. The infection of five non-STEC strains by nine Stx-encoding phages occurred at a rate of approximately 40%. Non-STEC strains were transduced by Stx-encoding phage to become lysogenic strains, and seven convertant strains had stx1 and/or stx2 genes. Only the stx1 gene was transferred to the receptor strains without any deletion. Gene expression of a convertant having both stx1 and stx2 genes was confirmed to be up to 32 times higher for Stx1 in 6% NaCl osmotic media and twice for Stx2 in 4% NaCl media, compared with expression in low-salt environments. Therefore, a new risk might arise from the transfer of pathogenic genes from Stx-encoding phages to otherwise harmless hosts. Without adequate sterilization of food exposed to various environments, there is a possibility that the toxicity of the phages might increase.

• Korean Journal of Veterinary Service
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• v.46 no.4
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• pp.325-334
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• 2023

Edema disease (ED) in pigs is enterotoxemia caused by Shiga toxin type 2e (Stx2e)-producing Escherichia coli (STEC) and frequently occurs in young piglets. Therefore, ED causes enormous economic losses in pig farms. In this study, a modified Stx2e (mStx2e) antigen was expressed and purified using commercial E. coli expression system. Monoclonal antibody was serviced by Ynto Ab Inc., using Phage Display Technique. Anti-Stx2e antibodies in piglets were measured by indirect ELISA using mStx2e antigens. Naive Stx2e in piglets were detected by Sandwich ELISA using Stx2e-monoclonal antibodies and commercial Stx2e-polyclonal antibodies. Among 3,480 piglets, anti-Stx2e antibodies were observed in 2,573 piglets. The 49.4% among 830 piglet serum samples possessed 0.625 ㎍/mL or more of Stx2e proteins. The 18.3% of 830 sera had 0.313 ㎍/mL of Stx2e proteins. The 32.3% of 830 samples held 0.156 ㎍/mL or less of Stx2e proteins. These results show that indirect ELISA using mStx2e antigen and Sandwich ELISA using Stx2e-monoclonal and polyclonal antibodies can be useful to detect ED in piglets.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.551-559
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• 2004

Shiga toxin-producing Escherichia coli (STEC) causes various clinical signs in human and animals, and has been indicated as a global enteropathogen with zoonotic importance. In this study, the feces of healthy pigs were collected from the slaughtered pigs of Daejon abattoir during the period from December 2001 to October 2002. Of 326 specimens, 13 STEC were confirmed by culture, PCR and colony hybridization. The isolates were further studied for toxin types, pathogenic factors, plasmid profiles, and antimicrobial resistance to characterize the genetic and toxigenic properties. In PCR, all of 13 isolates were evident to have shiga toxin gene (stx). Of 13 isolates stx1 gene was detected in 4 and stx2 gene in 9. The genes of eaeA, hlyA and rfbE were not present in any isolates. In colony hybridization using shiga toxin common primer (STXc), 2 to 9 per 100 colonies subcultured from 13 isolates showed the positive reaction. In the examination for plasmid profiles of the isolates, one to eleven plasmids with varying sizes of 1.0 Kb to 100 Kb were detected, and the 13 STEC could be classified into four groups by the plasmid patterns. The antimicrobial resistance patterns of the isolates were comparably corresponded with the plasmid profile patterns.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.121-128
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• 2020

Diarrhea is a major public health concern associated with pathogenic Escherichia coli infections. Food-borne pathogenic E. coli can lead to large diarrheal outbreaks and hence, there is a need to estimate the frequency of pathogenic E. coli load in the various types of meat available in markets. In the present study, we classified and characterized diarrheagenic E. coli isolates collected from 399 raw meat samples from retail sources in Korea. Shiga toxin-producing E. coli (STEC) were detected in 11 (9.7%) samples, including nine strains (8.0%) in beef and two strains (1.8%) in chicken. The frequency of the detected virulence markers were as follows: astA, 28.3%; escV,18.6%; eaeA,17.7%; ent, 7.0%; EHEC-hly, 4.4%; stx1, 3.5%; and stx2, 3.5%. We did not observe any typical EPEC, EIEC, or ETEC virulence determinants in any of the samples. The STEC serotype O26 was detected in one sample, but no other serogroups (O91, O103, O128, O157, O145, O111, and O121) were found. Further research is needed to better understand the virulence mechanism of STEC serotypes, their ecology, and prevalence in animals, food, and the environment. These results will help improve risk assessment and predict the sources of food poisoning outbreaks.

• Journal of Animal Science and Technology
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• v.63 no.2
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• pp.461-464
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• 2021

Escherichia coli normally colonizes the lower intestine of animals and humans, but some serotypes are foodborne pathogens. The Escherichia coli K_EC180 was isolated from swine feces that were collected from a weaner pig. In this genome announcement, E. coli K_EC180 was sequenced using PacBio RS II and Illumina NextSeq 500 platforms. The complete chromosome of E. coli K_EC180 is composed of one circular chromosome (5,017,281 bp) with 50.4% of guanine + cytosine (G + C) content, 4,935 of coding sequence (CDS), 88 of tRNA, and 22 of rRNA genes. The complete genome of E. coli K_EC180 contains the toxin genes such as shiga-like toxins (stxA and stxB).

• Journal of Food Hygiene and Safety
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• v.32 no.2
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• pp.129-134
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• 2017

Diarrheagenic Escherichia coli is now recognized as an important cause of diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome (HUS) worldwide. E. coli were isolated from 80 of 356 (22.5%) chicken and chilled chicken products in Korea. Fifteen virulence genes specific for pathogenic E. coli, including Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC), were examined by multiplex PCR. STEC virulence markers were detected for eaeA (20.0%), escV (21.3%), stx1 (3.8%), ent (2.5%), EHEC-hly (1.3%), stx2 (1.3%), EAEC virulence marker (astA) was detected in 32.5%. ETEC and EIEC were not detected. STEC serotypes O152, O1, O116, O26, O25, O119 and O153 were found in chicken samples. This suggests the importance of diarrheagenic Escherichia coli control in raw chicken and chilled chicken food for food safety.