• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.13-17
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• 2003

The studies were carried out to identification of biochemical characteristics and serogroup of 55 Vibrio cholerae non-01 isolated from sea waters and shellfish from Apr., 1996 to Nov., 1996 in Korea coastal, and clinical sources from 1984 to 1996 in Korea hospitals. The results were as followed: V. cholerae non-O1 isolated 21 (10%) of 206 samples and the distribution in Kusan area was highest (16%) compared with those of other area, and its were not isolated during low water temperature of 13-18$^{\circ}C$. Of 55 strains, a strain was delayed sucrose utilization for 48hr in the biochemical characteristics. Fifty five V. cholerae non-O1 were differentiated 15 types by serogroup test and O14 of sea waters were 76% of highest followed by 14 clinical sources were O8.

• Korean Journal of Veterinary Research
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• v.36 no.1
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• pp.109-118
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• 1996

The Salmonella rfb gene encoding for the biosynthesis of the oligosaccharide-repeating units of the O-antigenic determinants was cloned and sequenced. A set of nucleotide primers(a forward and reverse) was selected to target a defined region of the guanosine diphospho-mannose(GDP-Man) pyrophosphorylase synthase gene : rfbM of Salmonella C serogroup. The primer set was used to develop a PCR-based rapid and specific detection system for Salmonella C1 serogroup. Amplification bands of predicted size(1,422bp) were generated from 11 different Salmonella C1 isolates. The bands were verified to be specific for the C1 serogroup by Southern blot analysis using reference homologous DNA specificity was further confirmed by the lack of reactivity with heterologous DNA derived from non-salmonella members of the family enterobacteriaeceae. A specificity of 100% was deduced along with a very high sensitivity shown by a detection limit of 1fg of a purified DNA template. The isolated DNA sequence was found to be 99.8% homologous to S montevideo but the related primers amplified with the predicted band sizes with all the Salmonella C1 serogroups tested. It is concluded that the PCR protocol based on the rfbM gene from S cholerasuis is optimal fast and specific for the detection of Salmonella C1 serogroup and also the corresponding probe is suitable for rapid detection of all Salmonella C1 serogroup DNA tested. This technology should facilitate the identification of contaminated pig products and for any other products contaminated with the Salmonalla C1 serogroup. The immediate impact of this developed method will be in the area of food safety of pig products with the potential prospect for adaptation to other food inspection technologies.

• 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.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2006.11a
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• pp.92-93
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• 2006

This study was conducted to investigate O group serotyping, antimicrobial drug resistance and distribution of extended spectrum ${\beta}$-lactamase of 203 Escherichia coli(E. coli) isolated from poultry in Korea during the period from April in 2003 to December 2005. The serogroup of 69.4% of isolates was determinated ; O 78(32.5%), O88(7.9%). O15(6.9%) and O141(6.4%) were the most common. These E. coli isolates showed resistance to nalidixic acid(92.6%), streptomycin(81.8%), ampicillin(77.3%), ciprofloxacin(70.9%), sulfisoxazole(66.5%) and trimethoprim(58.1%), respectively. The bla CTX$_{-M-3\;like}$(2 strains) and bla$\;_{CMY-2}$(2 strains) genes producing extended spectrum ${\beta}$ - lactamase(ESBL) were detected in four wild strains resistant to the third generation cephalosporin, respectively. The presence of the ESBL genes was confirmed in all transconjugants by PCR analysis with primers encoding CTX-M-3 like types or CMY-2.

• Journal of Veterinary Clinics
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• v.17 no.2
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• pp.316-320
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• 2000

The present study conducted to evaluate the isolation frequency of Salmonella sap., Escherichia O157:H7 and Listeria monocytogenes in fecal samples collected form 33 dairy cow feedlots in West Gyeong-nam province from tan. 179\ulcorner to Feb. 1999. Salmonella spp. were isolated from 8.7% of fecal samples and 57.5% of dairy cow feedlots participaiting in this study had at least one positive fecal 7ample. The isolation rates of Salmonella spp. in each herd size were 42.9% in ln less than 125 heads, 63.6% in 25% to 50 heads and 75% in more than 50 heads. Of the positive sample, the most common serogroup recovered was Bl(31.5%), followed by C1 and D(22.9%), C2(16.2%), A(4.2%) and E(2.1%), in order. However, E. coli O157:H7 and Listeria monocytogenes were net detected in the fecal samples collected from all feedlots.

• 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.

• Journal of Veterinary Science
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• v.23 no.1
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• pp.9.1-9.11
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• 2022

Background: Escherichia coli, which causes subclinical or clinical mastitis in cattle, is responsible for transmitting antimicrobial resistance via human consumption of raw milk or raw milk products. Objectives: The objective of this study was to investigate the molecular characteristics of 183 E. coli from bulk tank milk of five different dairy factories in Korea. Methods: The molecular characteristics of E. coli such as serogroup, virulence, antimicrobial resistance, and integron genes were detected using polymerase chain reaction and antimicrobial susceptibility were tested using the disk diffusion test. Results: In the distribution of phylogenetic groups, group D was the most prevalent (59.6%) and followed by group B1 (25.1%). The most predominant serogroup was O173 (15.3%), and a total of 46 different serotypes were detected. The virulence gene found most often was fimH (73.2%), and stx1, fimH, incC, fyuA, and iutA genes were significantly higher in isolates of phylogenetic group B1 compared to phylogenetic groups A, B2, and D (p < 0.05). Among 64 E. coli isolates that showed resistance to at least one antimicrobial, the highest resistance rate was observed for tetracyclines (37.5%). All 18 integron-positive E. coli carried the integron class I (int1) gene, and three different gene cassette arrangements, dfrA12+aadA2 (2 isolates), aac(6')-Ib3+aac(6')-Ib-cr+aadA4 (2 isolates), and dfrA17+aadA5 (1 isolate) were detected. Conclusions: These data suggest that the E. coli from bulk tank milk can be an indicator for dissemination of antimicrobial resistance and virulence factors via cross-contamination.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.4
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• pp.577-584
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• 2016

The objectives of this study were I) to compare the acid resistance (AR) of seven non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups, including O26, O45, O103, O111, O121, O145, and O157:H7 STEC isolated from various sources, in 400 mM acetic acid solution (AAS) at pH 3.2 and $30^{\circ}C$ for 25 min with or without glutamic acid and II) to determine strain survival upon exposure to simulated gastric fluid (SGF, pH 1.5) at $37^{\circ}C$ for 2 h after acid adaptation in apple, pineapple, orange, and strawberry juices at pH 3.8, $4^{\circ}C$ and $20^{\circ}C$. Results show that the O111 serogroup strains had the strongest AR (0.12 log reduction CFU/mL) which was very similar to that of O157:H7 STEC (P>0.05), compared to other serogroups in AAS without glutamic acid, whereas O26 serogroup strains showed the most sensitive AR. However, there was no significant (P>0.05) difference of AR among seven serogroups in AAS with glutamic acid. In the SGF study, 05-6545 (O45:H2), 08023 (O121:H19), and 03-4669 (O145:NM) strains adapted in fruit juices at $4^{\circ}C$ and $20^{\circ}C$ displayed enhanced survival with exposure to SGF for 60 min compared to 06E0218 (O157:H7) strains (P<0.05). In addition, 4 STEC strains adapted in pineapple juice at $4^{\circ}C$ showed enhanced survival with exposure to SGF for 60 min compared to those strains acid-adapted in the other fruit juices. Generally, adaptation at $4^{\circ}C$ in fruit juices resulted in significantly enhanced survival levels compared to acid-adapted at $20^{\circ}C$ and non-adapted conditions. The AR caused by adaptation in fruit juices at low temperature may thus increase survival of non-O157 STEC strain in acidic environments such as the gastrointestinal tract. These results suggest that more careful strategies should be provided to protect against risk of foodborne illness by non-O157 STEC.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2199-2205
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• 2016

Vibrio cholerae O1 serogroup Wave 3 El Tor strains are presently prevalent worldwide. The Wave 3 El Tor strains contain a TLC:RS1:CTX array on chromosome 1, and no element is integrated on chromosome 2. A multiplex PCR optimized to identify the TLC:RS1:CTX array of Wave 3 strains has been developed in this study. By using eight primers, the multiplex PCR can identify the characteristic CTX and RS1 array of Wave 3 strains from various arrays of strains belonging to other Waves. The four amplified DNA fragments of Wave 3 strains have been cloned in a vector, which could be used as a positive control for the multiplex PCR. This multiplex PCR and the positive control set could be useful tools for rapid recognition of Wave 3 El Tor strains.

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.725-731
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• 2014

The classical biotype strains of the Vibrio cholerae O1 serogroup harbor the biotype-specific cholera-toxin encoding phage (CTX) $CTX^{cla}$, and the El Tor biotype strains contain CTX-1. Although the classical biotype strains have become extinct, a remnant of classical CTX phage is transferred to the El Tor biotype strains. The prototype El Tor strains, which produce the biotype-specific cholera toxin, are now being replaced by atypical El Tor variant strains producing classical biotype cholera toxin. The genome sequences of the CTX phages in atypical El Tor strains indicate that the CTX phages in atypical El Tor strains are a mosaic of $CTX^{cla}$ and CTX-1. Before the emergence of atypical El Tor stains in the early 1990s, unusual pre-seventh pandemic strains were isolated in the US Gulf Coast between 1973 and 1986. These strains have characteristics of atypical El Tor strains since they are El Tor biotype strains containing $CTX^{cla}$, yet the genome sequence of this CTX phage indicates that it is different from $CTX^{cla}$ and is therefore classified separately as $CTX^{US\;Gulf}$.