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8 "Gyung Tae Chung"
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Original Articles
Genome Sequencing Analysis of Atypical Shigella flexneri Isolated in Korea
Nan-Ok Kim, Hae-young Na, Su-Mi Jung, Gyung Tae Chung, Hyo Sun Kawk, Sahyun Hong
Osong Public Health Res Perspect. 2017;8(1):78-85.   Published online February 28, 2017
DOI: https://doi.org/10.24171/j.phrp.2017.8.1.11
  • 2,264 View
  • 20 Download
AbstractAbstract PDFSupplementary Material
Objectives

An atypical Shigella flexneri strain with a plural agglutination pattern [i.e., reacting not only with serum samples containing type antigen II but also with serum samples containing group antigens (3)4 and 7(8)] was selected for genome sequencing, with the aim of obtaining additional comparative information about such strains.

Methods

The genomic DNA of atypical S. flexneri strain NCCP 15744 was sequenced using an Ion Torrent PGM sequencing machine (Life Technologies, USA). The raw sequence data were preprocessed and reference-assembled in the CLC Assembly Cell software (version 4.0.6; CLC bio, USA).

Results

Ion Torrent sequencing produced 1,450,025 single reads with an average length of 144 bp, totaling ~209 Mbp. The NCCP 15744 genome is composed of one chromosome and four plasmids and contains a gtrX gene. Among the published genome sequences of S. flexneri strains, including 2457T, Sf301, and 2002017, strain NCCP 15744 showed high similarity with strain 2002017. The differences between NCCP 15744 and 2002017 are as follows: i) NCCP 15744 carries four plasmids whereas 2002017 carries five; ii) 19 genes (including CI, CII, and cro) were lost in the SHI-O genomic island of NCCP 15744 and six genes were gained as compared with strain 2002017.

Conclusion

Strain NCCP 15744 is genetically similar to 2002017, but these two strains have different multilocus sequence types and serotypes. The exact reason is unclear, but the 19 lost genes may be responsible for the atypical seroconversion of strain NCCP 15744.

Surveillance of Bacillus cereus Isolates in Korea from 2012 to 2014
Su-Mi Jung, Nan-Ok Kim, Injun Cha, Hae-young Na, Gyung Tae Chung, Hyo Sun Kawk, Sahyun Hong
Osong Public Health Res Perspect. 2017;8(1):71-77.   Published online February 28, 2017
DOI: https://doi.org/10.24171/j.phrp.2017.8.1.10
  • 2,115 View
  • 31 Download
  • 2 Citations
AbstractAbstract PDF
Objectives

To investigate the prevalence and toxin production characteristics of non-emetic and emetic Bacillus cereus strains isolated via the laboratory surveillance system in Korea.

Methods

A total of 667 B. cereus strains were collected by the Korea National Research Institute of Health laboratory surveillance system from 2012 to 2014. The collected strains were analyzed by geographical region, season, patient age, and patient sex. Additionally, the prevalence rates of enterotoxin and emetic toxin genes were evaluated.

Results

The isolation rate of B. cereus strains increased during the summer, but the isolation rate was evenly distributed among patient age groups. Emetic toxin was produced by 20.2% of the isolated strains. The prevalence rates of five enterotoxin genes (entFM, nheA, cytK2, hblC, and bceT) were 85.0, 78.6, 44.5, 36.6, and 29.7%, respectively, among non-emetic strains and 77.8, 59.3, 17.8, 11.9 and 12.6%, respectively, among emetic strains. Thus, the prevalence rates of all five enterotoxin genes were lower in emetic B. cereus.

Conclusion

The prevalence of enterotoxin genes differed between non-emetic and emetic B. cereus strains. Among emetic B. cereus strains, the prevalence rates of two enterotoxin genes (cytK2 and hblC) were lower than those among the non-emetic strains. In both the emetic and non-emetic strains isolated in Korea, nheA and entFM were the most prevalent enterotoxin genes.

Brief Reports
Occurrence of Norovirus GII.4 Sydney Variant-related Outbreaks in Korea
Sunyoung Jung, Bo-Mi Hwang, Hyun Ju Jeong, Gyung Tae Chung, Cheon-Kwon Yoo, Yeon-Ho Kang, Deog-Yong Lee
Osong Public Health Res Perspect. 2015;6(5):322-326.   Published online October 31, 2015
DOI: https://doi.org/10.1016/j.phrp.2015.10.004
  • 1,403 View
  • 17 Download
  • 7 Citations
AbstractAbstract PDF
Human noroviruses are major causative agents of food and waterborne outbreaks of nonbacterial acute gastroenteritis. In this study, we report the epidemiological features of three outbreak cases of norovirus in Korea, and we describe the clinical symptoms and distribution of the causative genotypes. The incidence rates of the three outbreaks were 16.24% (326/2,007), 4.1% (27/656), and 16.8% (36/214), respectively. The patients in these three outbreaks were affected by acute gastroenteritis. These schools were provided unheated food from the same manufacturing company. Two genotypes (GII.3 and GII.4) of the norovirus were detected in these cases. Among them, major causative strains of GII.4 (Hu-jeju-47-2007KR-like) were identified in patients, food handlers, and groundwater from the manufacturing company of the unheated food. In the GII.4 (Hu-jeju-47-2007KR-like) strain of the norovirus, the nucleotide sequences were identical and identified as the GII.4 Sydney variant. Our data suggests that the combined epidemiological and laboratory results were closely related, and the causative pathogen was the GII.4 Sydney variant strain from contaminated groundwater.
Epidemics of Norovirus GII.4 Variant in Outbreak Cases in Korea, 2004–2012
Sunyoung Jung, Hyun Ju Jeong, Bo-Mi Hwang, Cheon-Kwon Yoo, Gyung Tae Chung, Hyesook Jeong, Yeon-Ho Kang, Deog-Yong Lee
Osong Public Health Res Perspect. 2015;6(5):318-321.   Published online October 31, 2015
DOI: https://doi.org/10.1016/j.phrp.2015.10.002
  • 1,515 View
  • 19 Download
  • 1 Citations
AbstractAbstract PDF
Norovirus GII.4 is recognized as a worldwide cause of nonbacterial outbreaks. In particular, the GII.4 variant occurs every 2–3 years according to antigenic variation. The aim of our study was to identify GII.4 variants in outbreaks in Korea during 2004–2012. Partial VP1 sequence of norovirus GII.4-related outbreaks during 2004–2012 was analyzed. The partial VP1 sequence was detected with reverse transcription-polymerase chain reaction, seminested polymerase chain reaction, and nucleotide sequence of 312-314 base pairs for phylogenetic comparison. Nine variants emerged in outbreaks, with the Sydney variant showing predominance recently. This predominance may persist for at least 3 years, although new variants may appear in Korea.
Original Article
Enteric Bacteria Isolated from Diarrheal Patients in Korea in 2014
Nan-Ok Kim, Su-Mi Jung, Hae-Young Na, Gyung Tae Chung, Cheon-Kwon Yoo, Won Keun Seong, Sahyun Hong
Osong Public Health Res Perspect. 2015;6(4):233-240.   Published online August 31, 2015
DOI: https://doi.org/10.1016/j.phrp.2015.07.005
  • 1,550 View
  • 18 Download
  • 10 Citations
AbstractAbstract PDFSupplementary Material
Objectives
The aim of this study was to characterize the pathogens responsible for causing diarrhea according to season, region of isolation, patient age, and sex as well as to provide useful data for the prevention of diarrheal disease.
Methods
Stool specimens from 14,886 patients with diarrhea were collected to identify pathogenic bacteria from January 2014 to December 2014 in Korea. A total of 3,526 pathogenic bacteria were isolated and analyzed according to season, region of isolation, and the age and sex of the patient.
Results
The breakdown of the isolated pathogenic bacteria were as follows: Salmonella spp. 476 (13.5%), pathogenic Escherichia coli 777 (22.0%), Vibrio parahaemolyticus 26 (0.74%), Shigella spp. 13 (0.37%), Campylobacter spp. 215 (6.10%), Clostridium perfringens 508 (14.4%), Staphylococcus aureus 1,144 (32.4%), Bacillus cereus 356 (10.1%), Listeria monocytogenes 1 (0.03%), and Yersinia enterocolitica 10 (0.3%). The isolation rate trend showed the highest ratio in the summer season from June to September for most of the pathogenic bacteria except the Gram-positive bacteria. The isolation rate of most of the pathogenic bacteria by patient age showed highest ratio in the 0–19 year age range. For isolation rate by region, 56.2% were isolated from cities and 43.8% were isolated from provinces.
Conclusion
Hygiene education should be addressed for diarrheal disease-susceptible groups, such as those younger than 10 years, aged 10–19 years, and older than 70 years, and monitoring for the pathogens is still required. In addition, an efficient laboratory surveillance system for infection control should be continued.
Corrigendum
Corrigendum to “Investigation of Biofilm Formation and its Association with the Molecular and Clinical Characteristics of Methicillin-resistant Staphylococcus aureus” [Volume 4, Issue 5, October 2013, Pages 225–232]
Jeong-Ok Cha, Jae Il Yoo, Jung Sik Yoo, Hae-Sun Chung, Sun-Hee Park, Hwa Su Kim, Yeong Seon Lee, Gyung Tae Chung
Osong Public Health Res Perspect. 2014;5(2):116-116.   Published online April 30, 2014
DOI: https://doi.org/10.1016/j.phrp.2014.04.002
  • 1,373 View
  • 19 Download
PDF
Original Article
Investigation of Biofilm Formation and its Association with the Molecular and Clinical Characteristics of Methicillin-resistant Staphylococcus aureus
Jeong-Ok Cha, Jae Il Yoo, Jung Sik Yoo, Hae-Sun Chung, Sun-Hee Park, Hwa Su Kim, Yeong Seon Lee, Gyung Tae Chung
Osong Public Health Res Perspect. 2013;4(5):225-232.   Published online October 31, 2013
DOI: https://doi.org/10.1016/j.phrp.2013.09.001
  • 1,692 View
  • 13 Download
  • 44 Citations
AbstractAbstract PDF
Objectives
To investigate the biofilm-forming related factors against MRSA bloodstream isolates and evaluates their clinical features and treatment outcomes by biofilm production.
Methods
We collected 126 consecutive methicillin-resistant Staphylococcus aureus (MRSA) causing blood stream infections (BSIs) at 10 tertiary hospitals from 2007 to 2009. We investigated biofilm-forming ability using a microtiter plate assay, and molecular characteristics including multilocus sequence typing, staphylococcal cassette chromosome mec and accessory gene regulator types. We compared the clinical characteristics and outcomes of patients infected with biofilm-forming and non-biofilm-forming MRSA isolates.
Results
Of the 126 samples, 86 (68.3%), including 5 strong level (OD570 ≥ 1.0) and 81 weak level (0.2 ≤ OD570 < 1.0), had biofilm-forming capacity. Detection of fibronectinbinding protein in biofilm-forming strains was significantly higher than biofilm non-forming ones (p = 0.001) and three enterotoxin genes (sec-seg-sei) islands had a high frequency regardless of biofilm production. However, biofilm-forming strains were more likely to be multidrug resistant (three or more non-β-lactam antibiotics) than biofilm non-forming ones [79.2% vs. 59.2%, p = 0.015, odds ratio (OR) 2.629, 95% confidence interval (CI) 1.92–5.81]. Clinical features of patients with BSIs caused by biofilm-forming MRSA strains were more likely to be hospital onset [77.9% vs. 60.0%, p = 0.024, OR 2.434, 95% CI 1.11–5.33) and more frequently occurred in patients with use of invasive devices [85.7% vs. 61.2%, p = 0.002, OR 3.879, 95% CI 1.61–8.97]. The other clinical features were compared with the clinical outcomes of the two groups and were not significant (p > 0.05).
Conclusion
Biofilm-forming MRSA strains showed higher frequency of fnbB gene than biofilm non-forming ones and more incidence rates on particular genotypes. And, their patient's features were not significantly different between two groups in this study, except for several clinical factors.
Articles
Alterations of gyrA, gyrB, and parC and Activity of Efflux Pump in Fluoroquinolone-resistant Acinetobacter baumannii
Sunok Park, Kyeong Min Lee, Yong Sun Yoo, Jung Sik Yoo, Jae Il Yoo, Hwa Su Kim, Yeong Seon Lee, Gyung Tae Chung
Osong Public Health Res Perspect. 2011;2(3):164-170.   Published online December 31, 2011
DOI: https://doi.org/10.1016/j.phrp.2011.11.040
  • 1,388 View
  • 14 Download
  • 25 Citations
AbstractAbstract PDF
Objectives
This study investigated the fluoroquinolone-resistant mechanism of 56 clinical cases of A baumannii infection from 23 non-tertiary hospitals, collected between 2004 and 2006.
Methods
Susceptibility testing was performed by broth microdilution and Epsilometer test. Analyses of quinolone resistance-determining region (QRDR) were done by sequencing. The activity of the efflux pump was measured using inhibitors.
Results
The sequences from selected 56 isolates were divided into seven groups (I-VII) on the basis of mutations in gyrA (S83L), parC (S80L, S80W and S84K) and gyrB (containing the novel mutations E679D, D644Y and A677V). The 27 isolates with triple mutations in gyrA, gyrB and parC (groups IV-VII) showed higher levels of resistance to ciprofloxacin (minimal inhibitory concentration [MIC] of 16-256 μg/mL) than the 26 isolates with double mutations in gyrA and parC (groups II and III, MIC of 8-64 μ g/mL; p < 0.05). Alterations in the efflux pump were observed in four isolates with the parC S80L mutation (group II) or E84K mutation (group VII), but no effect was observed in an isolate with the parC S80 W mutation (group III).
Conclusion
These results suggest that triple mutations in clinical isolates of A baumannii contribute to the development of high levels of resistance to fluoroquinolones and that mutations in parC S80L or E84K (groups II and VII) may contribute to alterations in efflux pump activity in A baumannii.

PHRP : Osong Public Health and Research Perspectives