| Nan-Ok Kim | 4 Articles |
<sec><b>Objectives</b><p>An atypical <italic>Shigella flexneri</italic> 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.</p></sec><sec><b>Methods</b><p>The genomic DNA of atypical <italic>S. flexneri</italic> 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).</p></sec><sec><b>Results</b><p>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 <italic>gtrX</italic> gene. Among the published genome sequences of <italic>S. flexneri</italic> 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 <italic>CI</italic>, <italic>CII</italic>, and <italic>cro</italic>) were lost in the <italic>SHI-O</italic> genomic island of NCCP 15744 and six genes were gained as compared with strain 2002017.</p></sec><sec><b>Conclusion</b><p>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.</p></sec>
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<sec><b>Objectives</b><p>To investigate the prevalence and toxin production characteristics of non-emetic and emetic <italic>Bacillus cereus</italic> strains isolated via the laboratory surveillance system in Korea.</p></sec><sec><b>Methods</b><p>A total of 667 <italic>B. cereus</italic> 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.</p></sec><sec><b>Results</b><p>The isolation rate of <italic>B. cereus</italic> 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 (<italic>entFM</italic>, <italic>nheA</italic>, <italic>cytK2</italic>, <italic>hblC</italic>, and <italic>bceT</italic>) 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 <italic>B. cereus</italic>.</p></sec><sec><b>Conclusion</b><p>The prevalence of enterotoxin genes differed between non-emetic and emetic <italic>B. cereus</italic> strains. Among emetic <italic>B. cereus</italic> strains, the prevalence rates of two enterotoxin genes (<italic>cytK2</italic> and <italic>hblC</italic>) were lower than those among the non-emetic strains. In both the emetic and non-emetic strains isolated in Korea, <italic>nheA</italic> and <italic>entFM</italic> were the most prevalent enterotoxin genes.</p></sec>
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<b>Objectives</b><br/>
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.<br/><b>Methods</b><br/>
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.<br/><b>Results</b><br/>
The breakdown of the isolated pathogenic bacteria were as follows: <i>Salmonella</i> spp. 476 (13.5%), pathogenic <i>Escherichia coli</i> 777 (22.0%), <i>Vibrio parahaemolyticus</i> 26 (0.74%), <i>Shigella</i> spp. 13 (0.37%), <i>Campylobacter</i> spp. 215 (6.10%), <i>Clostridium perfringens</i> 508 (14.4%), <i>Staphylococcus aureus</i> 1,144 (32.4%), <i>Bacillus cereus</i> 356 (10.1%), <i>Listeria monocytogenes</i> 1 (0.03%), and <i>Yersinia enterocolitica</i> 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.<br/><b>Conclusion</b><br/>
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.
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<b>Objectives</b><br/>
We aimed at evaluating the virulence of atypical <i>Shigella flexneri</i> II:(3)4,7(8) by DNA microarray and invasion assay.<br/><b>Methods</b><br/>
We used a customized <i>S. flexneri</i> DNA microarray to analyze an atypical <i>S. flexneri</i> II:(3)4,7(8) gene expression profile and compared it with that of the <i>S. flexneri</i> 2b strain.<br/><b>Results</b><br/>
Approximately one-quarter of the atypical <i>S. flexneri</i> II:(3)4,7(8) strain genes showed significantly altered expression profiles; 344 genes were more than two-fold upregulated, and 442 genes were more than 0.5-fold downregulated. The upregulated genes were divided into the category of 21 clusters of orthologous groups (COGs), and the “not in COGs” category included 170 genes. This category had virulence plasmid genes, including the <i>ipa-mxi-spa</i> genes required for invasion of colorectal epithelium (type III secretion system). Quantitative reverse-transcription polymerase chain reaction results also showed the same pattern in two more atypical <i>S. flexneri</i> II:(3)4,7(8) strains. Atypical <i>S. flexneri</i> II:(3)4,7(8) showed four times increased invasion activity in Caco-2 cells than that of typical strains.<br/><b>Conclusion</b><br/>
Our results provide the intracellularly regulated genes that may be important for adaptation and growth strategies of this atypical <i>S. flexneri</i>.
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