• Journal of Microbiology
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• v.42 no.2
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• pp.80-86
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• 2004

Pulsed-field gel electrophoresis (PFGE) typing was applied to the epidemiological investigation of 21 Candida tropicalis isolates collected from urine specimens of 11 patients and one healthcare worker, in an intensive care unit (ICU) over a 4-month period. Seventeen epidemiologically unrelated strains from 14 patients were also tested to determine the discriminatory power of PFGE. PFGE typing consisted of electrophoretic karyotyping (EK) and restriction endonuclease analysis of genomic DNA (REAG), using two restriction enzymes (BssHII and SfiI). The EK pattern was the same in all 38 isolates, while REAG using SfiI separated the isolates into nine types. However, 16 different PFGE types were iden-tified by REAG with BssHII, and the same results were obtained when the results of both REAG tests were combined. In serial urinary isolates from 10 patients, all strains from each patient had the same PFGE pattern. While the epidemiologically unrelated strains from 14 patients consisted of 13 different PFGE types, the 20 isolates from the 11 ICU patients fell into only two PFGE types (types Cl and C2), and these apparently originated from the two different outbreaks. All strains of type Cl (n = 12) were isolated from six patients, between November 1999 and January 2000, and all of the type C2 strains (n=8) were isolated from five patients, during January and February 2000. This study shows two con-secutive clusters of C. tropicalis candiduria in an ICU, defined by PFGE typing, and also demonstrates that a PFGE typing method using BssHII is perhaps the most useful method for investigating C. tropi-calis candiduria.

• Korean Journal of Veterinary Research
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• v.46 no.2
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• pp.107-117
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• 2006

This paper described the epidemiological characteristics of 2002 outbreak of classical swine fever (CSF) in Korea. A total of thirteen CSF-infected farms could be classified into two clusters according to the location and time of outbreak. Two farms located in the same county of Gangwon province and 11 farms located in several different districts of Incheon metropolitan/Gyeonggi province were identified as CSF-infected from April 16 to 30 and from October 7 to December 21 in 2002, respectively. As the result of epidemiological analysis, the two clusters of outbreaks were turned out to be independent epidemics which had different sources of virus introduction. Three farms were found to have been infected primarily; one located in Cheolwon county of Gangwon province and two located in Kangwha county of Incheon metropolitan area. The most likely factors of virus introduction into these primary infected farms were considered to be direct or indirect contact by foreign workers and/or owners of the infected farms who had come back from traveling in China before outbreaks. This was supported by the genetic typing of CSF viruses isolated from the pigs of infected farms. All the virus isolates of 2002 outbreak were found to be genetic type 2, whereas the viruses isolated before 2000 were type 3 and the reference strains, such as attenuated live vaccine virus (LOM strain) and high virulent challenge virus (ALD strain), were type 1. Accordingly, we concluded that the 2002 CSF outbreak must have been caused by a newly introduced virus from overseas and the type 3 virus must have been eradicated after the last outbreak of 1999 by the national CSF eradication campaign which were implemented since 1996. Based on the combined analysis of epidemiological data and genetic typing, the transmission routes of classical swine fever virus were found to be the movement of vehicles (60%) and persons (10%), neighbourhood spread (20%) and unknown (10%). It is expected that the analyzed data and findings of classical swine fever outbreak epidemic could be very useful to establish the disease control and eradication program for the country in the future.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1467-1470
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• 2012

We compared rapid fingerprinting using repetitive sequencebased PCR (rep-PCR) for subtyping Campylobacter jejuni isolates to the widely used multilocus sequence typing (MLST). Representative C. jejuni isolates (n = 16) from broilers were analyzed using MLST and rep-PCR. Both techniques demonstrated an equal discriminatory power of 0.8917, and 9 subgroups were identified. Clonal identification of all 16 isolates was identical for both techniques. The rep-PCR as described in this study may be used as a rapid and cost-effective alternative for subtyping of C. jejuni isolates, or as an effective screening tool in large epidemiological studies.

• Korean Journal of Veterinary Service
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• v.40 no.1
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• pp.1-6
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• 2017

Molecular typing of pathogenic microorganisms is important for epidemiological investigation of infectious disease outbreaks. In this study, we applied Universal Rice Primers (URP) that were originated from repetitive sequences in rice chromosomal DNA to random amplified polymorphic DNA (RAPD) analysis of pathogenic bacteria such as Escherichia coli, Listeria monocytogenes, and Salmonella sp. Of the twelve URP primers examined to date, seven primers (URP-2, -3, -4, -5, -6, -8, and -9) generated reproducible and polymorphic PCR products ranging from 1 to 13 bands. One of them, URP-6 was very effective in differentiating seven E. coli serotypes, seven L. monocytogenes clinical isolates, and eight Salmonella subspecies (ssp.) serovars. The results thus indicate that RAPD analysis using URP primers might be useful in typing bacterial pathogens including E. coli, L. monocytogenes, and Salmonella strains.

• Journal of Korean Biological Nursing Science
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• v.10 no.2
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• pp.147-153
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• 2008

Purpose: Methicillin Resistant Staphylococcus aureus (MRSA) has become a major clinical problem and one of the major nosocomial pathogen worldwide. The aim of the study was to investigate the epidemiological characteristics of genotypes of MRSA isolated in the A-hospital ICU. Methods: In the period between December 2007 and May 2008, MRSA was isolated from ICU patients and its surrounding environment. Polymerase Chain Reaction (PCR) was conducted for the detection of MRSA gene. The incidence of MRSA in the clinical isolates of Staphylococcus aureus was examined by using a multiplex PCR. The spa gene of Staphylococcus aureus encodes protein A and is used for typing of MRSA. We used sequence typing of the spa gene repeat region to study the epidemiology of MRSA at a hospital. Results: Two different genotypes of MRSA were identified with 90 isolated from the patients and its surrounding environments in the ICU. Conclusion: This study may contribute to the development of effective strategies for preventing nosocomial infections. Genotyping may have more general application for the study of MRSA epidemic outbreak in hospital and community infection.

• Biomedical Science Letters
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• v.5 no.2
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• pp.135-145
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• 1999

A total of 45 Staphylococcus aureus strains from clinical samples were tested for the biochemical test and antibiotic susceptibility test. Forty-five S. aureus strains were subjected to the molecular epidemiological study by susceptiblity test, antibiogram, bacteriophage typing, polymerase chain reaction and mec-associated hypervariable region gene in order to detect of mecA gene which was one of the structural gene related to antibiotic resistant expression factors. Three of 15 mecA-negative S. aureus isolates were classified as oxacillin resistant despite borderline minimal inhibitory concentration values. Methicillin susceptiblities were completely consistent with PCR results for these strains. On the other hand, 4 of 30 mecA-positive isolates yielded results in the oxacillin and methicillin susceptibility tests which were discrepant from those of PCR analysis. Except for SA6, the methicillin resistant S. aureus strains tested were highly resistant to penicillin, oxacillin, gentamicin, and chloramphenicol. In the phage typing, 27 strains were typable. The Iytic group III was as many as 12 strains, and 7 of 12 were 75/83A/84 type. In the PCR of specific mecA gene probe with chromosomal DNA of 30 methicillin resistant S. aureus, the amplified DNA band of 533 bp was confirmed in 30 strains and not in methicillin sensitive S. aureus. The single amplified band of hypervariable region related to mec was investigated in all of 30 methicillin resistant S. aureus, but in methicillin sensitive S. aureus it was amplified. The size of PCR products was between 200 bp and 600 Up. Four units was directly repeated.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.4
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• pp.265-272
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• 2022

The emergence and dissemination of carbapenemase-producing Enterobacteriaceae (CPE), particularly the Klebsiella pneumoniae carbapenemase-2 (KPC-2) producing Klebsiella pneumoniae, has been rapidly increasing worldwide and is becoming a serious public health threat. Since the epidemiology and characteristics of these KPC-2-producing K. pneumoniae vary according to the region and period under consideration, this study investigated the prevalence of carbapenemases and the epidemiological relationship of 78 carbapenem-resistant K. pneumoniae (CRKP) isolated from a tertiary hospital in Daejeon, from March 2017 to December 2020. The antimicrobial susceptibility tests were identified using the disk-diffusion method. PCR and DNA sequencing were used to determine the carbapenemase genes. In addition, molecular epidemiology was performed by multilocus sequence typing (MLST). Among the 78 CRKP isolates, 35 isolates (44.9%) were carbapenemase-producing K. pneumoniae (CPKP) and the major carbapenemase type was KPC-2 (30 isolates, 85.7%). The New Delhi metallo-enzyme-1 (NDM-1) and NDM-5 were identified in 4 isolates (11.4%) and 1 isolate (2.9%), respectively. Multilocus sequence typing (MLST) analysis showed 10 sequence types (STs) and the most prevalent ST was ST307 (51.4%, 18/35). All the ST307 isolates were KPC-2-producing K. pneumoniae and were multidrug-resistant (MDR). In addition, ST307 has gradually emerged during a four-year period. These findings indicate that continuous monitoring and proper infection control are needed to prevent the spread of KPC-2-producing K. pneumoniae ST307.

• Korean Journal of Veterinary Research
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• v.58 no.1
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• pp.51-55
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• 2018

Bovine mastitis (BM) has resulted in enormous economic loss in the dairy industry and coagulase-negative staphylococci (CNS) have caused subclinical BM. Although VITEK 2 GP ID card (VITEK 2) has been used for CNS identification, the probability of identification varies. The rpoB sequence typing (RSTing) method has been used for molecular diagnosis and epidemiology of bacterial infections. In this study, we undertook RSTing of CNS and compared the results with those of VITEK2 and 16S rRNA gene sequencing. As compared VITEK2, the molecular-based methods were more reliable for species identification; moreover, RSTing provided more molecular epidemiological information than that from 16S rRNA gene sequencing.

• Korean Journal of Veterinary Service
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• v.34 no.3
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• pp.217-226
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• 2011

Salmonella spp. is of increasing public health concern as causative pathogens of food poisoning. The aim of this study was to investigate the serotypes and antimicrobial resistance pattern of Salmonella spp. isolated from duck farms in Daegu-Gyeongbuk province. Also, S. Enteritidis and S. Typhimurium isolates were further examined for plasmid analysis, phage typing and pulsed-field gel electrophoresis (PFGE). A total of 34 Salmonella spp. (16.4%) were isolated from duck farms and ten serotypes were identified. The predominant serotypes were S. Typhimurium (23.5%) S. Fyris (17.6%) and S. Haardt (11.8%), S. Agona and S. Enteritidis (respectively 8.8%). Of 34 Salmonella isolates, 15 (44.1%) isolates were resistant to at least one antimicrobial agent and multiple resistance (resistance to more than 4 drugs) was observed in 9 strains (26.5%). The high resistance was found to streptomycin (32.4%), tetracycline (29.4%), ampicillin, kanamycin and nalidixic acid (respectively, 26.5%), all Salmonella isolates were susceptible to cefoxitin, cefotaxime, gentamicin, amikacin and ciprofloxacin. All S. Enteritidis and S. Typhimurium isolates were found to contain only one plasmid (ca. 54 or 55kb, respectively). Among the S. Enteritidis isolates, two phage types were found, PT32a and PT1c, respectively, one isolates did not react with any of the phages used. Whereas, all S. Typhimurium isolates were RDNC (reacts but does not conform). PFGE showed to be a useful typing method better than plasmid analysis and phage typing for discrimination of isolates especially, S. Typhimurium isolates. Our results indicated that the serotypes of Salmonella isolates are widely distributed in duck farms, further epidemiological studies should be carried out.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.106-113
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• 2002

One-hundred and twenty-four trimethoprim-resistant Shigella sonnei isolates extracted in Korea during the last two decades were investigated for their epidemiological relationship and mechanisms of resistance to trimethoprim. The S. sonnei isolates were distributed into two groups by three different epidemiological tools: biotyping, antibiogram, and pulsed-field gel electrophoresis. One group contained the isolates from the 1980s and the other group included the isolates from the 1990s. The geometric mean MICs of trimethoprim in S. sonnei isolates from the 1980s and 1990s were found to be $672.9{\mu}g/ml\;and\;>2,048{\mu}g/ml$, respectively. Trimethoprim resistance was associated with dfrA5, dfrA12, and dfrA13 genes in the isolates from the 1980s, dfrA1, dfrA5, and dfrA12 in the isolates from 1991, and dfrA1 and dfrA12 in the isolates from 1992 to 1999. The dfrA1 gene was located downstream of the intI2 gene in Tn7, which was located on chromosome. Some dfrA12 genes were found as gene cassettes in the class 1 integron. The dfrA5 and dfrA13 genes were located on conjugative plasmids. These results suggested that a clonal change occurred in S. sonnei isolates in Korea during the last two decades and that dfr genes located on different transposable genetic elements had gradually changed.