| Yeon-Ho Kang | 6 Articles |
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.
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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.
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<b>Objectives</b><br/>
To investigated whether the CTX-M-14 gene could be transferred from a clinical <i>Shigella sonnei</i> strain to commensal <i>Escherichia coli</i> strain in the gastroenteritis microbiome.<br/><b>Methods</b><br/>
<i>E. coli</i> strains were isolated from 30 stool samples of <i>S. sonnei</i> infected students in a gastroenteritis outbreak in 2004 and were characterized by antibiotic resistance analysis, <i>in vitro</i> conjugation and <i>in vivo</i> transfer of CTX-M-14 gene and molecular assays.<br/><b>Results</b><br/>
One strain of <i>Escherichia coli</i> that had high levels of resistance to cefotaxime was isolated from a patient infected with <i>S. sonnei</i>. Isoelectric focusing showed that the <i>E. coli</i> and <i>S. sonnei</i> strains produced a β-lactamase with an isoelectric point of 8.1. Moreover, polymerase chain reaction analysis indicated that both strains possessed the same DNA sequences for CTX-M-14. The results of <i>in vitro</i> and <i>in vivo</i> conjugation showed that the efficiency of CTX-M-14 transfer from <i>S. sonnei</i> to <i>E. coli</i> was similar to CTX-M-14 transfer between <i>E. coli</i> strains.<br/><b>Conclusion</b><br/>
The data suggest that the acquisition of the extended-spectrum β-lactamases gene by pathogenic bacteria in the human intestinal tract to commensal microbiome bacteria can cause serious infectious diseases.
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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>.
<b>Objectives</b><br/>
The aim of this study is to compare the antibiotic resistance of <i>Escherichia coli</i> isolates from faecal samples of workers who often use antibiotics.<br/><b>Methods</b><br/>
A total of 163<i>E coli</i> strains isolated from faecal samples of livestock workers (poultry and swine farm workers) and restaurant workers in the same regions as a control group were analyzed by agar disc diffusion to determine their susceptibility patterns to 16 antimicrobial agents.<br/><b>Results</b><br/>
Most of the tested isolates showed high antimicrobial resistance to ampicillin and tetracycline. The isolates showed higher resistance to cephalothin than other antibiotics among the cephems. Among the aminoglycosides, the resistance to gentamicin and tobramycin occurred at higher frequencies compared with resistance to amikacin and netilmicin. Our data indicated that faecal <i>E coli</i> isolates of livestock workers showed higher antibiotic resistances than nonlivestock workers (restaurant workers), especially cephalothin, gentamicin, and tobramycin (<i>p</i> < 0.05). Moreover, the rates of the livestock workers in the association of multidrug resistance were also higher than the rates of the restaurant workers.<br/><b>Conclusion</b><br/>
This study implies that usage of antibiotics may contribute to the prevalence of antibiotic resistance in commensal <i>E coli</i> strains of humans.
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<b>Objectives</b><br/>
This study aimed to investigate the prevalence of antibiotic resistance in fecal <i>Escherichia coli</i> isolates from healthy persons and patients with diarrhea.<br/><b>Methods</b><br/>
<i>E. coli</i> isolates (<i>n</i> = 428) were obtained from fecal samples of apparently healthy volunteers and hospitalized patients with diarrhea. Susceptibility patterns of isolates to 16 antimicrobial agents were determined by agar disc diffusion.<br/><b>Results</b><br/>
Most <i>E. coli</i> isolates exhibited less than 10% resistance against imipenem, cefotetan, aztreonam, cefepime, cefoxitin, amikacin and netilamicin, although greater than 65% were resistant to ampicillin and tetracycline. No significant difference in resistance rates for all tested antibiotics was found between isolates from the healthy-and diarrheal-patient groups, including for multi-drug resistance (<i>p</i> = 0.22). The highest number of resistant antibiotics was 12 antibiotics. No significant differences in antibiotic resistance were found among the sex and age strata for isolates from healthy individuals. However, antibiotic resistance rates to cefoxitin, cefotaxime, amikacin, and netilamicin were significantly higher in the isolates of men than those of women (<i>p</i> < 0.05) in isolates from patients with diarrhea. Furthermore, isolates from patients with diarrhea older than 40-years of age showed higher resistance to cefepime and aztreonam (<i>p</i> < 0.05).<br/><b>Conclusion</b><br/>
High resistance to the antibiotics most frequently prescribed for diarrhea was found in isolates from patients with diarrhea and apparently healthy individuals without any significant difference.
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