• 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 the Korean Applied Science and Technology
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• v.39 no.6
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• pp.916-923
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• 2022

Water samples were collected from three spots(Namcheon, Changwoncheon and Cheongwoonji) in Changwon and genomic DNA was isolated from them. Quantitative PCR was performed with the isolated DNA as template and primers targeting five different class A extended-spectrum beta-lactamase(ESBL) genes(bla_OXA-1, bla_SHV, bla_TEM, bla_CTX-M-1, bla_CTX-M-9). The number of total ESBL genes from each sample showed large variations between each sample. Thirty nanograms of DNA from Namcheon contained 1.93×10⁶ copies of ESBL genes whereas the same amount of DNA from Changwoncheon contained 1.47×10⁵ copies of ESBL genes. However, the same amount of DNA from Cheongwoonji pond contained only 9.5×10³ copies of ESBL genes. The ratio of each ESBL genes showed little difference between Namcheon river and Changwoncheon river, but DNA from Cheongwoonji pond showed a large difference from the rest. bla_OXA-1 gene was present at 65.3%, and bla_CTX-M-1 gene 33.6% for Namcheon comprising together almost 99%. bla_OXA-1 gene was present at 64.1%, and bla_CTX-M-1 gene 19.1% for Changwoncheon comprising together over 83%. bla_CTX-M-1 gene was present at 87.5% and bla_CTX-M-9 genes 9.8% for Cheongwoonji, a pond which is a closed and isolated environment.

• Journal of Veterinary Science
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• v.23 no.3
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• pp.37.1-37.8
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• 2022

Background: Avian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry. Objectives: In this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates. Methods: The molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing. Results: The two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates. Conclusions: This study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.

• Korean Journal of Microbiology
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• v.35 no.3
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• pp.205-210
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• 1999

16brio cholerne is an important pathogenic organism that causes dimhea in human beings. V ciaoleroe KNIH002 was isolated from patients suffering with dian.heal disease in Korea. From Southern hybridization using the amplified PCR product of 307 bp as a probe. which was obtained from PCR reaction using primer detecting cholera toxin gene, we have found that the c b gene located in 4.5-kb fragmenl double digested with Pstl and BgllI of the chromosome. Therefore, we made mini-libraries of the isolate using PstI and Bgm restriction endonuclease and pBluescript SKU(+) vector. As a result. we cloned 4.5-kb PstI-BglII fragment containing the c a gene encoding a cholera toxin from the constructed mini-libraries of V olzolerae KNlH002 by colony hybridization using the same probes. This recombinant plasmid was named pCTX75. E. coii XL1- Blue harboring pCTX75 showed the cytotoxicity on Chinese Hamster Ovary cells. From the sequencing of he cloned recombinant plasmid, we confinned that it has virulence gene cassette consisting of ace, zot, ctx.4 and cf"~B gene. The ace and zot genes were composed of 291 hp and 1.200 bp with ATG initiation codon and TGA lennination codon, respectively. Nucleotide sequence of the ace gene exhibited 100% identity with that of V cholera E7946 El Tor Ogawa strains. But, nucleolide and amino acid sequence comparison of the zot gene exhibited 99% and 98.8% identity with that of V cholerae 395 Classical Ogawa stram, respectively. Specially. the Ala-100, Ala-272 and Ala-281 sites of Zoi polypeptide presented in V choleme 395 Classical Ogawa strain are replaced by Val in V cholerae KNIH002.

• Microbiology and Biotechnology Letters
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• v.34 no.4
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• pp.342-351
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• 2006

The aim of this study was to survey susceptibilities of Escherichia coli and Klebsiella pneumoniae isolates against cefotaxime and to determine the prevalences of CTX-M type extended-spectrum $\beta$-lactamases (ESBLs) producing E. coli and K. pneumoniae in Korea. During the period of February to July, 2005, 153 E. coli and 52 K. neumoniae isolates were collected from 2 hospitals in Busan. Antimicrobial susceptibilities to cefotaxime were tested by the disk diffusion method. ESBL production of E. coli and K. pneumoniae was determined by the double disk synergy test. MICs of $\beta$-lactam antibiotics were determined by the agar dilution method. Blac$_{CTX-M}$ genes of the organism were detected by PCR. Among 153 isolates of E. coli and 52 isolates of K. neumoniae, 27 (17.6%) and 25 (48.0%) were intermediate or resistant to cefotaxime, respectively. Twenty-three (15.0%) isolates out of 153 E. coli and 13 (25.0%) out of 52 K. neumoniae isolates showed positive results for ESBL by the double disk synergy test. Twenty isolates out of 23 ESBL producing E. coli and 12 out of 13 ESBL producing K. neumoniae isolates harbored biacTx-M gene,11 of ESBL producing E. coli and 12 of ESBL producing K. neuinoniae isolates harbored bla$_{CTX-M}$ gene, 11 of the ESBL producing E. coli and 2 of ESBL producing K. neumoniae isolates harbored bla$_{TEM}$ gene, and 1 of the ESBL producing E. coli and 12 of ESBL producing K. neumoniae isolates harbored bla$_{SHV}$ gene. E. coli and K. neumoniae isolates producing CTX-M-type ESBLs were not uncommon in Korea. It is thought that continuous survey are necessary for inspecting the spread and novel variants of CTX-M-type ESBL genes. Further me]'e investigation and research on ESBL producing strains are needed in order to prevent the spread of resistant bacteria.

• Journal of Life Science
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• v.23 no.5
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• pp.703-709
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• 2013

The aim of this study was to investigate the prevalence of Extended-spectrum ${\beta}$-lactamase (ESBL) gene and quinolone resistance determinant (qnr) and the pattern of antibiotic resistance in the ESBL-producing Escherichia coli clinical isolates. The 42 ESBL-producing strains from total 274 isolates were detected using a double disk synergy test. They were isolated from various specimens, such as urine (28 strains), sputum (6 strains), pus (3 strains), wound (2 strains), blood (2 strains), and tissue (1 strain). Using the PCR with the specific primers ESBL, ESBL and qnr gene types were determined. Thirty-five strains possessed one or two ESBL genes. CTX-M-1 type was the most abundant followed by CTX-M-9 type and TEM, but SHV, CTX-M-2, and CTX-M-8 gene types were not detected. qnr gene types were detected from ten isolates in the order of qnrB4, qnrB1, and qnrS. Coexistence of ESBL and qnr genes was found. ESBL-producing isolates showed high resistance against some antibiotics, such as cefotaxmie (80.0%), levofloxacin (82.9%), and ampicillin (100%). Neither a synergy effect from the coexistence of ESBL and qnr genes on antibiotic resistance nor a correlation between the production of qnr gene and quinolone resistance were found.

• Proceedings of the Microbiological Society of Korea Conference
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• 2000.05a
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• pp.58-65
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• 2000

Diarrheal diseases are a major cause of both illness and death in developing countries and are caused by rotavirus, Shigella spp., Salmonella spp., enterotoxigenic Escherichia coli (ETEC), and Vibrio spp. In this study, for the development of vaccine against diarrheal diseases caused by Shigella sonei, Salmonella typhimurium, E. coli O157, and Vibrio cholerae, cloning and nucleotide sequence analysis of genes and characteristics of their gene products in E. coli were performed. For construction of attenuated strain of S. sonnei KNIH104 and Salmonella typhimurium KNIH100, the aroA genes were cloned, respectively. The recombinant plasmid $_pJP{\Delta}A45$ containing aroA deleted region and suicide vector $(_pJP5603)$ was constructed. The aroA gene deleted mutants were constructed using this recombinant plasmid. For cloning gene encoding antigenic region of E. coli O157 KNIH317, the O-antigen synthesis gene cluster and sit gene was cloned. The E. coli XL1-Blue cells harboring this recombinant plasmid showed cytotoxicity in Vero cells. The ctx gene was cloned for tile purpose of antigenic region against V. cholerae KNIH002. Sequence analysis confirmed that the virulence gene cassette was consisted of ace, zot, ctxA and ctxB genes.

• The Journal of the Korean Society for Microbiology
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• v.34 no.6
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• pp.513-518
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• 1999

A total of 113 Vibrio sp. strains were examined for plasmid content which were subjected to digestion with restriction enzymes. About the 55% Vibrio spp. have the plasmid more than one. Most of these plasmid various derivatives ranged from $2.4\;kb{\sim}23\;kb$, especially two strains of V. mimicus and one strain of V. furnissii carried one high-molecular weight plasmid (molecular weight ranging between $70\;kb{\sim}100\;kb$). Results of restriction analysis for plasmid of this three strains were by no means the rule. For detection of tdh and ctx gene, the virulence factor involved in the pathogenesis, we carried out the TDH and CT assay, PCR amplification, and hybridization. A total 11 strains were produced TDH, involved in 9 strains of V. parahaemolyticus and 1 strain of V. alginolyticus from clinical isolates and 1 strains of V. mimicus from environmental isolates. In the experiments of tdh gene detection, in all, 3 strains of V. parahaemolyticus from clinical isolates and 2 strains from environmental isolates could be successfully amplified in 400 bp by PCR. The PCR results were consistent with DNA hybridization tests. In the experiments of CT assay, in all, 3 strains of V. cholerae from clinical isolate and 1 strain of V. cholerae from environmental isolates were observed CT-producing. These CT-producing strains amplified in 302 bp by PCR for the detection of ctx gene. All CT-producing strains hybridized with digoxigenin-labeled DNA probe, while CT-negative strains did not hybridize. Also hybridization tests results for detection of ctx gene consistent with PCR.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2224-2227
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• 2016

Shigella sonnei harboring $bla_{CTX-M-55}$ was isolated outside of Asia for the first time. The $bla_{CTX-M-55}$ gene was found to be downstream of ISEcp-1 and located in a ~130 kb conjugative plasmid belonging to the I1 incompatibility group. The strain was recovered from a 7-year-old Ecuadorian girl with watery diarrhea who had not travelled abroad. Recent local data describe the emergence of $bla_{CTX-M-55}$ and other variants typically found in Asia in the Andean Region, suggesting that increased travel of humans and trade relationships with Asian countries are influencing the current Ecuadorian bacterial resistance situation.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1643-1649
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• 2016

The aims of this study were to characterize the molecular epidemiological profiles of CTX-M-producing uropathogenic Escherichia coli isolates from a tertiary hospital in Daejeon, Korea, and to investigate the genetic diversity and compare the prevalence of sequence types (STs) in different areas. Extended spectrum β-lactamase-producing E. coli strains isolated from urine were analyzed for CTX-M, integrons, and insertion sequence common regions (ISCRs) by PCR and sequencing. Multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), phylogenetic analysis, and rep-PCR were also used for molecular typing of the isolates. Of 80 CTX-M producers, 31 and 46 expressed CTX-M-15 and CTX-M-14, respectively. MLST analysis indicated that the most prevalent ST was ST131 (n = 34, 42.5%), followed by ST38 (n = 22, 27.5%), ST405 (n = 8, 10.0%), and ST69 (n = 6, 7.5%). Most CTX-M producers harbored class 1 integrons. ST131 strains belonged to phylogenetic group B2 and showed identical rep-PCR patterns, whereas ST69, ST38, and ST405 strains belonged to phylogenetic group D; the ST38 and ST405 strains displayed the same rep-PCR pattern, respectively. ST131 and ST38 isolates showed 21 and 19 distinct types, respectively, by PFGE. In Daejeon, D-ST38 CTX-M-14 producers were relatively more prevalent than in other countries and Korean cities. Our results indicate that CTX-M-producing E. coli isolates belonged mostly to ST131 or ST38 and were more related to hospital-onset than to community-onset infections and that the bla_CTX-M gene may vary according to the ST.