• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.183-188
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• 1999

The incidence of Yersinia enterocolitica in raw meat was determined over 10 month period. Y. enterocolitica was isolated from 8.5% of beef, 17.0% of pork and 25.6% of chicken. Overall prevalence of Y. enterocolitica in raw meat was 17.5%. Seasonal difference was observed in isolation rate in which pork and chicken samples collected in the second half of the year twice was more than that of the first half of the year. Serotypes of Y. enterocolitica isolates were O:5 (17.3%), O:8 (8.6%), O:3 (6.2%), O:1,2 (1.2%), and others. The antibiotics susceptibility tests showed Y. enterocolitica isolates were resistant to carbenicillin, ampicillin, erythromycin, penicillin and bacitracin. In contrast it showed sensitivity to polymyxin B, kanamycin, ciprofloxacin, gentamicin, trimethoprim/sulfamethoxazole, nalidixic acid, and tetracycline. PCR with specific primers derived from ail gene of Y. enterocolitica was applied to detect and confirm pathogenic Y. enterocolitica. About 10% of the isolated Y. enterocolitica proved to be pathogenic and most of them were found in pork. However, proper cooking and meat process can kill and remove all Y. enterocolitica in meat, because the organism is very sensitive to heat.

• Biomedical Science Letters
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• v.8 no.3
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• pp.107-113
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• 2002

Enterohemorrhagic Escherichia coli (EHEC) strains of serotype O157:H7 have been shown to colonize the intestinal epithelial cell by the attaching and effacing (AE) mechanism. The AE lesion is mediated by an intimin, of which production and expression are controlled by a 3-Kb eaeA gene located EHEC chromosomal DNA. If the eaeA gene is mutated, EHEC O157:H7 strains lose capacity of adhesion to intestinal epithelial cells. In this study, a 891 bp of the 3'-end region of a gamma intimin was amplified by polymerase chain reaction (PCR). The PCR product was inserted into pSTBlue-1 cloning vector and transformed into DE3 (BL21) competent cell. After plasmid mini-preparation and restriction enzyme digestion of eaeA/891-pSTBlue-1 vector, target eaeA gene was re-inserted into pET-28a expression vector and was transformed. Then the expression of recombinant eaeA/891 (891 bp) gene was induced by isopropyl-$\beta$-D-thiogalactopyranoside (IPTG). The expression of the 40-KDa recombinant protein was identified in SDS-PAGE and confirmed by immunoblotting using the His.Tag$^{\circledR}$ and T$_{7}$.Tag$^{\circledR}$ monoclonal antibody. This recombinant protein expressed by eaeA gene could be applied in further studies on the mechanisms of E. coli O157:H7 infection and the development of recombinant vaccine.

• Journal of Microbiology and Biotechnology
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• v.23 no.5
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• pp.731-737
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• 2013

Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.

• Biomedical Science Letters
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• v.28 no.2
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• pp.127-136
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• 2022

Uropathogenic Escherichia coli (UPEC) is main causative agent of urinary tract infections. They are classified based on various types of O antigen. UPEC strains commonly possess many genes encoding virulece-associated factors. E. coli strains are generally divided into four main phylogenetic groups. The virulence factor (VF) profiles of UPEC are related with their O-serogroups in each strains. A total of 681 strains of UPEC clinical isolates were collected from Korean healthcare facility (1989: 123 strains and 2010-2014: 558 strains). The UPEC clinical isolates were analyzed by polymerase chain reaction (PCR) methods. A total of 14 O-serotypes (O1, O2, O4, O6, O7, O8, O15, O16, O18, O21, O22, O25, O75 and O83), 6 virulence factors (papC, fimG/H, sfaD/E, hly1, cnf1 and usp) and phylogenetic groups were identified. The most prevalent O-serogroups were O6 (11.1%) in 1989 UPEC strains and O25 (21.0%) in 2010-2014 UPEC strains. The identified VFs, phylogenetic groups in 1989 UPEC strains and 2010-2014 UPEC strains were fimG/H and B2 group. In this study, O6 serotype was revealed the close relationships with VFs. Also, the distribution of prevalence O-serogroups of UPEC has been changed from O6 to O25 and virulence of UPEC strains was increased during past twenty-one years.

• Korean journal of food and cookery science
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• v.27 no.4
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• pp.17-26
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• 2011

This study was performed to analyze the antibacterial activity against food hazardous microorganisms and antimutagenic effects of Sanguisorba officinalis L. ethanol extracts on Salmonella Typhimurium TA100. The antibacterial activity was evaluated by paper disc diffusion assay, minimum inhibition concentration (MIC), and optical density of the culture with the ethanol extract for 24 hr. Antibacterial activity was tested with seven microorganisms including Escherichia coli, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella Typhimurium, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. The paper disc diffusion assay showed distinct clear inhibition zones around the discs treated with the extract for five microorganisms, except Escherichia coli and Escherichia coli O157:H7. MIC values were 0.625-2.5 mg/mL for these five strains that showed clear zones. The time-kill assay was consistent with the results from the paper disc diffusion assay and MIC test. Additionally, antimutagenicity of the extract was determined using the Ames test. The ethanol extract at 5 mg/plate inhibited 72.42% and 89.85% of mutagenicity induced by 4-nitroquinoline 1-oxide and sodium azide, respectively. These results demonstrate that the ethanol extract from S. officinalis L. has remarkable antibacterial activity and antimutagenicity.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.334-341
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• 2003

This study was carried out to investigate the cause of cholera outbreak in Gyeongbuk province in 2001.90 strains of Vibrio cholerae O1 El Tor serotype Inaba were isolated from diarrheal patients. By multiplex-PCR, all of the isolated strains revealed positive for detection ctxA, hlyA and tcpA genes. There were DNA sequence difference of the cholera-toxin subunit A gene and subunit B gene between isolated V. cholerae O1 and the strain of GenBank. In analysis of PFGE patterns, all of the isolated strains were showed the same DNA fragments. We also collected plankton samples in the east coast of Gyeongbuk to isolate V. cholerae O1 and V. cholerae O139 from August to October 2002. The samples were examined to detect the rfb gene and cholera-toxin gene by multiplex-PCR. The cholera-toxin gene was detected and then we tried to isolate V. cholerae O1 and V. cholerae O139, but they were not isolated.

• 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.

• Journal of Food Hygiene and Safety
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• v.12 no.4
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• pp.354-360
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• 1997

This study was intended that the biochemical patterns, bioserological characteristics, resistance of antibiotics, and transferable resistance patterns of 35 Dscherichia coli strains from 79 fish and shellfish samples in marine markets from August to October, 1995. The Standard plate count, coliforms and fecal coliforms were also counted in the 79 cases and analysed the correlationship each other. Geometric means of Standard plate count in seawater fish, shellfish, mollusca and crustacean were 1.4$\times$105 CFU/g, 4.0$\times$105 CFU/g, 2.4$\times$105 CFU/g, 4.7$\times$105 CFU/g, and those of coliforms were 1.3$\times$103 CFU/g, 4.8$\times$103 CFU/g, 8.9$\times$102 CFU/g, 5.8$\times$103 CFU/g. There were no fecal coliforms in the fish and mollusc. However, the geometric means of coliforms in the shellfish and crustacean (1.1$\times$101 CFU/100g, 10 CFU/100 g) were less than those of fish and mollusca. The important biochemical characteristics of E. coli distinguished from the shellfish and crustacean were motility, ornithine decarboxylase, mucate, esculin. The fermentative properties of E. coli were also sucrose, salicin, sorbitol, and raffinose. Of 35 isolates of E. coli, 13 strains (37.1%) showed the pathogenic O antisera, which were O:27 3 strains (23.1%), ):159 2 strains (15.4%) and ):148, O:119, O:142, O:158, O:136, O:18, O:128, and O:168 1 strain (7.7%),respectively.

• Korean Journal of Veterinary Service
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• v.20 no.4
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• pp.359-370
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• 1997

This study was carried out to Investigate the biochemical characteristics, antibiotic susceptibility, serogroups and pili producibility test of enterotoxigenic Escherichia coli(ETEC) isolated from piglets with diarrhea in Kangwon province from March to October 1996. 1. Sixty eight E coli strains were isolated from 72 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. 2. The serogroups of 26 isolates were classified as 08 : K87 6(8.8%), O20 : K1O1 4(5.9%), O141 : K85 4(5.9%), 09 : K103 : P987 3(4.4%), O45 : K 2(2.9%) 0139 : K82 2(2.9%), O64 : $K^{-}$2(2.9%), O149 : K91 1(1.5%), O157 : K88ac 1(1.5%) and O115 : $K^{-}$1(1.5%), respectively. 3. In antibiotic susceptibility test, the isolates showed high susceptible to Ak, Eno, Na, Gm, Am and Km, whereas resistance to Tc, Sm and Cf. 4. Sixty one strains(89.7%) of 68 I coli Isolates were resistant to one or more drugs. The isolates resistant to 2 and 3 or more drugs were 60.3% and 19.1%, respectively. Amog the 16 multiple resistant patterns, Sm Tc(11.5% ), Cf Sm Tc(11.5% ), Cf Cp Sm Su Tc(9.8% ) and Cf Cp Sm Su Tc(8.2%) patterns were frequently observed. 5. MRHA of guinea pig erythrocytes was detected in 9 out of 26 OK serotype and 9 out of 42 unidentified serotypes. MRHA titers of serotypes showed from 16 to 32 in O141 : K85 and no titers in O139 : K82. 6. By the GM1 ganglioside ELISA, $\beta$-, $\alpha$-, and $\gamma$-hemolysin producing strains was detected as 36, 6, and 5 from heat labile enterotoxin(LT) of 47 ETEC, respectively. The distribution of LT toxin from 112 isolates was showed $\beta$- hemolysin, 2 isolates $\alpha$-hemolysin and 3 isolates $\gamma$-hemol-ysin from 26 OK serotypes.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.509-516
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• 2003

A model system for the immnunochemical detection of Escherichia coli O157:H7 using a combined immunomagnetic separation (IMS) and test-strip liposome immunoassay (LIA) procedure was developed. Immunomagnetic beads coated with anti-E. coli O157 IgG antibodies were used to separate the E. coli O157 (including the H7 serotype) from culture. Immunoliposomes, whose surface was conjugated to goat anti-E. coli O157:H7 IgG and which encapsulated the marker dye, sulforhodamine B, were used as a detection label. The test strip, onto which antibodies to goat IgG were immobilized, was the immunosensor capturing immunoliposomes that did not bind to E. coli O157:H7 on the immunomagnetic bead-E. coli O157:H7 complexes. In experiments, pure cell culture suspensions of $10^5 E.$ coli O157:H7 organisms per ml produced a measurable signal inhibition, whereas a weak yet detectable signal inhibition occurred with $10^3CFU/ml$. The inhibition signals increased, when the incubation time for IMS was extended to 90 min and higher IgG-tag density (0.4mol%) was used on the liposomes. With 0.2 and 0.4mol% IgG-tagged liposomes, the IMS-LIA procedure showed more improved signal inhibitions than those of a direct (no IMS) LIA. The combined assay, which measures the instantaneous signal from immunoliposomes, can be completed within 90 min, making it significantly faster than conventional plating methods and enzyme-linked immunosorbent assay (ELISA). Accordingly, it is quite feasible to use the combined immunoassay format of IMS and dye-loaded immunoliposomes for the detection of E. coli O157:H7.