Osong Public Health and Research Perspectives

Jung-Whan Chon

3 Articles

Characterization of Clostridium difficile Strains Isolated from Patients with C. difficile-associated Disease in Korea: Seung-Hak Cho, Jung-Whan Chon, Kun-Ho Seo, Young Kwon Kim, Jung-Beom Kim, Young-Seok Bak, Woon-Won Jung, Cheorl-Ho Kim, Jong Tae Choi; Osong Public Health Res Perspect. 2017;8(5):325-331. Published online October 31, 2017; DOI: https://doi.org/10.24171/j.phrp.2017.8.5.06

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Abstract PDF: Objectives
Studies on Clostridium difficile are rare in Korea. We investigated the epidemiological characteristics of C. difficile isolates from patients with C. difficile-associated disease (CDAD) in Korea.
Methods
Multiplex polymerase chain reaction was performed to detect the presence of tcdA and tcdB toxin genes. Antimicrobial susceptibility test was carried out by the disk-dilution method. C. difficile strains were subtyped by automated repetitive-element palindromic PCR (rep-PCR).
Results
Among patients with CDAD, 73 (25.8%), 32 (11.3%), 32 (11.3%), and 26 (9.2%) suffered from pneumonia, cancer or neoplasm, diabetes, and colitis, respectively. Of all stool samples, 43 samples (15.2%) were positive for C. difficile strains. We observed two expression patterns of toxin genes: tcdA+/tcdB+ (86% isolates) and tcdA−/tcdB+ (14% isolates), with all isolates expressing tcdB. Furthermore, some isolates were resistant to clindamycin (65%), ampicillin (56%), and cefazolin (40%), but all were susceptible to vancomycin and metronidazole. The tested samples were classified into diverse clusters using automated rep-PCR.
Conclusion
Our findings revealed the characteristics and antibiotic resistance of C. difficile isolates from patients in Korea. The epidemiological data may provide valuable insight into development of treatment strategies for C. difficile infections in Korea.

Corrigendum to “A Comparison of Subtyping Methods for Differentiating Salmonella enteric Serovar Enteritidis Isolates Obtained from Food and Human Sources” [Volume 4, Issue 1, February 2013, Pages 27–33]: Ji-Yeon Hyeon, Jung-Whan Chon, Jun-Ho Park, Moo-Sang Kim, Young-Hee Oh, In-Soo Choi, Kun-Ho Seo; Osong Public Health Res Perspect. 2013;4(3):176-176. Published online June 30, 2013; DOI: https://doi.org/10.1016/j.phrp.2013.05.002

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A Comparison of Subtyping Methods for Differentiating Salmonella enterica Serovar Enteritidis Isolates Obtained from Food and Human Sources: Ji-Yeon Hyeon, Jung-Whan Chon, Jun-Ho Park, Moo-Sang Kim, Young-Hee Oh, In-Soo Choi, Kun-Ho Seo; Osong Public Health Res Perspect. 2013;4(1):27-33. Published online February 28, 2013; DOI: https://doi.org/10.1016/j.phrp.2012.12.005

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Abstract PDF: Purpose: To evaluate the abilities of these subtyping methods, we distinguished Salmonella Enteritidis (S. Enteritidis) isolated from food products and human clinical samples between 2009 and 2010 in Seoul using five subtyping methods.
Methods
We determined the subtypes of 20 S. Enteritidis isolates from food and human sources using phage typing, antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR (rep-PCR), and multi-locus sequence typing (MLST).
Results
A total of 20 tested isolates were differentiated into six antimicrobial susceptibility patterns, three different phage types, four different PFGE profiles, seven rep-PCR patterns, and one MLST type. Food isolates were considerably more susceptible to antibiotics than human isolates. We were best able to discriminate among S. Enteritidis isolates using rep-PCR, and obtained the highest Simpson’s diversity index of 0.82, whereas other methods produced indices that were less than 0.71. PFGE pattern appeared to be more related to antimicrobial resistance and phage types of S. Enteritidis isolates than rep-PCR. MLST revealed identical alleles in all isolates at all seven loci examined, indicating no resolution.
Conclusion
The results of this study suggest that rep-PCR provided the best discriminatory power for phenotypically similar S. Enteritidis isolates of food and human origins, whereas the discriminatory ability of MLST may be problematic because of the high sequence conservation of the targeted genes.

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