Detection of waterborne norovirus genogroup I strains using an improved real time RT-PCR assay.

Noroviruses (NoVs) are the major global source of acute gastroenteritis (AGE) outbreaks. To detect NoVs, real-time reverse transcription-quantitative PCR (RT-qPCR) assays have been widely employed since the first decade of the 21st century. We developed a redesigned probe, JJV1PM, for RT-qPCR assay detection of NoV genogroup (G) I strains. The new RT-qPCR assay using the JJV1PM-probe showed broader strain reactivity for 10 NoV GI genotypes, while the old method, using the JJV1PT-probe assay, detected only 7 NoV GI genotypes in a validation panel using human fecal specimens. The improved RT-qPCR assay was also successfully applied to water samples. The JJV1PM-probe assay identified 7 NoV GI genotypes, whereas the JJV1PT-probe assay detected only 2 NoV GI genotypes from water samples. Notably, groundwater-borne NoV GI strains detected by the improved JJV1PM-probe assay were associated with groundwater-borne AGE outbreaks in South Korea. The results of this study underscore the importance of the evaluation of RT-qPCR assays using recently circulating NoV strains prior to field application.

High prevalence of amantadine-resistant influenza A virus isolated in Gyeonggi Province, South Korea, during 2005-2010.

Amantadine resistance among influenza A viruses was investigated in South Korea in 2005-2010. Of 308 influenza A viruses examined, 229 had the S31N substitution in the M2 protein. The frequency of amantadine resistance was 30 %, 100 %, and 76 % in influenza A/H1N1, pandemic A/H1N1 2009(A/H1N1pdm), and A/H3N2 subtypes, respectively. The amantadine-resistant influenza A/H1N1pdm and A/H3N2 viruses were circulating continuously from 2008 to 2009 and from 2005 to 2006, respectively. Amantadine resistance among influenza A viruses increased dramatically during the 5-year study period, and this has diminished the usefulness of this class of drugs.

Evaluation of various PCR assays for the detection of emetic toxin producing Bacillus cereus.

Because conventional methods for detecting emetic-toxin-producing B. cereus are laborious and costly, various PCR assays, which are easy and cheap, have recently been reported. Therefore, this study estimated and compared the ability of various PCR assays to detect emetic-toxin-producing B. cereus strains isolated in Korea. The PCR assays were performed on 160 B. cereus strains, including 40 emetic-toxin-producing strains. Although the species-specific PCR assays were all shown to be highly specific, the sensitivities varied greatly. The accuracies of the primers were 97.5% (CER), 95.6% (EM1), 96.3% (RE234), 89.4% (CES), and 83.1% (Ces3R/CESR2). Moreover, the CER primer had a higher sensitivity (100%) than all the other primers tested, and a specificity of 96.7%. Thus, the CER primer was shown to be the most effective for screening the emetic-toxin-producing B. cereus strains tested in this study. However, the ability of these PCR assays to identify emetic-toxin-producing B. cereus should also be confirmed using other methods.

Draft Genome Sequence of Raphidiopsis raciborskii Strain GIHE 2018, Isolated from a Shallow Freshwater Pond in South Korea.

The draft genome sequence of Raphidiopsis (Cylindrospermopsis) raciborskii strain GIHE 2018, a filamentous nitrogen-fixing and potentially harmful cyanobacterium, is reported here. This is the first strain isolated from a shallow freshwater pond in South Korea. This information is expected to improve our understanding of the phylogeography of this species.

Draft Genome Sequence of Putative 2-Methylisoborneol-Producing Pseudanabaena yagii Strain GIHE-NHR1, Isolated from the North Han River in South Korea.

The draft genome sequence of Pseudanabaena yagii GIHE-NHR1, a filamentous cyanobacterium, is reported here. Comparative genome analysis suggests that this strain can produce an odor-causing compound (2-methylisoborneol) in water. The genome information is expected to improve the understanding of the putative 2-methylisoborneol production by the bacterium.

Genotypic distribution of rotavirus strains causing severe gastroenteritis in Gyeonggi province, South Korea, from 2003 to 2005.

Rotavirus was present in 1,367 of 7,060 stool samples (19.4%) collected in Gyeonggi province of South Korea from 2003 through 2005. The predominant genotypes were confirmed as G4/P2A[6] (19.0%) followed by G3/P1A[8] (15.6%), G2/P1B[4] (9.3%), and G1/P1A[8] (6.5%). The predominant types of rotavirus by year were G3/P[8] in 2003, G4/P[6] in 2004, and G1/P[8] in 2005. The prevalent rotavirus genotypes changed constantly from 2003 to 2005.

Investigation of Ginsenosides and Antioxidant Activities in the Roots, Leaves, and Stems of Hydroponic-Cultured Ginseng (Panax ginseng Meyer).

There has been very little reported on ginsenoside composition and antioxidant activity of hydroponic-cultured ginseng roots (HCR), leaves (HCL), and stems (HCS). We profiled 6 ginsenoside compounds in HCR, HCL, and HCS using high-performance liquid chromatography. Antioxidative activity of HCR, HCL, and HCS were evaluated using total phenolic content (TPC) and total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical-scavenging activity assays, and ferric reducing antioxidant power (FRAP) assays. Total ginsenoside contents of HCL and HCS were significantly higher than that of HCR (P<0.05). Rb1 was detected in HCR (23.02 mg/g) but was detected at very low levels in HCL and HCS (2.07~7.30 mg/g). Rg1 was the most abundant ingredient in HCL, followed by Rd; this was different than for HCR and HCS. The TPC and TFC ranged from 52.82~155.31 mg gallic acid equivalent/100 g and 194.71~256.52 mg quercetin equivalent/100 g, respectively, of which HCL contained the highest levels. Moreover, HCL was the most effective in both DPPH and FRAP activities. In this study, we also evaluated the inhibitory effect of HCR, HCL, and HCS on the activities of mushroom tyrosinase through whitening activity test. The inhibitory effect of HCL on tyrosinase activity was higher than that of HCR and HCS. This study provides information about ginsenoside contents and the antioxidative activity of hydroponic-cultured ginseng, and suggests that the whole ginseng plant (including roots, leaves, and stems) may be a beneficial functional vegetables.

Contents of chlorogenic acids and caffeine in various coffee-related products.

Coffee is the most popular beverage in the Republic of Korea, other than Korea's traditional green tea. Coffee contains many physiologically active substances, such as chlorogenic acids (CGAs) and caffeine. Previous studies have focused on the content of CGAs and caffeine in brewed coffee. This study quantified the total amounts of CGAs and caffeine using high-performance liquid chromatography coupled with a diode array detector in 83 various coffee-related products, such as instant coffee, roasted and ground coffee sold in supermarkets, ready-to-drink coffee, and Americano coffee sold in franchise restaurants in the Republic of Korea. According to the results of this study, the coffee with the highest content of CGAs was unblended roasted and ground coffee sold in supermarkets, with a mean value of 194.1 ±â€¯67.7 mg/serving, and the most caffeine-rich coffee was Americano coffee from coffee shops, with a mean value of 166.1 ±â€¯37.5 mg/serving. The caffeine/CGA ratios were determined in various coffee beverages because they are useful parameters for estimating the human health. The lowest mean caffeine/CGAs ratio of 0.5 ±â€¯0.1 was found in unblended ground coffee sold in supermarkets, and the highest mean ratio of 2.5 ±â€¯1.4 was found in milk-added ready-to-drink coffee. Adult caffeine tolerance is defined as 400 mg a day in the Republic of Korea. However, this value highlights the importance of medicines, carbohydrate beverages, tea, chocolate, cocoa products, energy drinks and other sources of caffeine that can contribute to the total intake of caffeine.

High incidence of group A rotaviruses G4P[6] strains among children in Gyeonggi province of South Korea, from 2009 to 2012.

The genotype distribution of group A rotaviruses (RVAs) circulating in Gyeonggi province, South Korea between 2009 and 2012 was investigated. A total of 2619 stool specimens from sporadic acute gastroenteritis cases and 117 acute gastroenteritis outbreaks were analyzed. Among them, RVAs were detected from 263 (10.0%) sporadic cases and 3 (2.6%) outbreaks. The G4P[6] strains predominated (29.7%), followed by G1P[8] (19.4%), G2P[4] (15.6%), G3P[8] (13.3%) and G9P[8] (6.5%) strain. Especially 96.2% of the genotype G4P[6] strains were isolated from children<1year of age. Phylogenetic analysis revealed that genotype G4P[6] strains were members of sub-lineage Ie(G4) and Ia(P[6]). Intensified monitoring of RVAs, especially G4P[6] strains among young children, is essential to control RVA infections.

Prevalence, genetic diversity, and antibiotic resistance of Bacillus cereus isolated from Korean fermented soybean products.

Bacillus cereus contamination is a major food safety problem for Korean fermented soybean products, but few studies have assessed its potential to cause foodborne illness. The objectives of this study were to investigate the prevalence and characteristics of B. cereus isolated from Korean fermented soybean products. B. cereus was detected in 110 of 162 (67.9%) samples. The highest B. cereus frequency was observed in deonjang (68 of 93 samples, 73.1%) and cheonggukjang (18 of 25, 72.0%); however, nonhemolytic enterotoxin was detected only in 22 of 162 samples (13.6%). Although the tested B. cereus isolates showed diverse pulsotypes according to repetitive sequence-PCR banding patterns, they displayed similar antibiotic sensitivity spectra. The low frequency of enterotoxin detection suggests that the potential risk of B. cereus foodborne illness associated with Korean fermented soybean products is lower than generally presumed. However, considering the prevalence of B. cereus and the high content of fermented soybean products in the Korean diet, it is necessary to constantly monitor the level of contamination with B. cereus and its toxins in such Korean food products.

Emergence of Norovirus GII.4 variants in acute gastroenteritis outbreaks in South Korea between 2006 and 2013.

BACKGROUND: New emerging strains of noroviruses (NoVs) often increase acute gastroenteritis (AGE) outbreaks worldwide. OBJECTIVE: We analyzed the epidemiological features and genotypic patterns of NoVs in AGE outbreaks. STUDY DESIGN: To elucidate the public health impact of NoVs during AGE outbreaks in South Korea, a molecular and epidemiological investigation was performed with 318 AGE outbreaks reported from the Gyeonggi province of South Korea during the period from 2006 to 2013. RESULTS: NoVs were associated with 102 (32.1%) of the AGE outbreaks. Epidemiological data revealed that the majority of NoV outbreaks were in the student group (47.1%), and the majority of AGE patients were identified in schools (68.8%). NoV genogroup (G) II strains were associated with 94 (92.2%) of the NoV outbreaks, and GII.4 strains were predominantly associated with 57.6% (n=49) of NoV GII outbreaks. Four GII.4 variants (2006b, 2007, 2009 and 2012 variants) emerged and showed different contributions to NoV outbreak activity. The 2006b variant was predominantly associated with NoV outbreaks during the early years of the study period, and was subsequently displaced by the New Orleans 2009 variant, and most recently by the Sydney 2012 variant. In addition, the GII.2, GII.14, and GII.17 strains have recently been often associated with NoV AGE outbreaks. CONCLUSIONS: The emergence of new NoV GII.4 variants significantly affected the NoV outbreak activity in South Korea during the period from 2006 to 2013. The surveillance for new emerging strains affecting NoV outbreak activity should be intensified to develop an adequate policy to prevent further NoV outbreaks.

Molecular epidemiology of norovirus GII.4 variants in children under 5 years with sporadic acute gastroenteritis in South Korea during 2006-2013.

BACKGROUND: The global emergence of norovirus (NoV) GII.4 variants has raised public concerns in the world including South Korea since 1996. OBJECTIVE: We analyzed seasonality and genotypic pattern for sporadic cases by norovirus GII-4 variants. STUDY DESIGN: To determine the epidemic status of GII.4 variants in South Korea during 2006-2013, 7301 fecal specimens were collected from children who were younger than 5 years and had sporadic acute gastroenteritis (AGE). RESULTS: During the study period, NoVs were the most prevalent viral agent, detected in 877 (12.0%) of the 7301 fecal specimens from children with sporadic AGE. NoV GII strains predominantly accounted for 97.6% of all sporadic NoV infections. NoV GII.4 was the most prevalent genotype and comprised 67.6% of the NoV GII strains. However, seasonal prevalence of GII.4 strains varied depending on the spread of GII.4 variants. GII.4-2006b variant most predominantly circulated from 2006-2007 to 2009-2010 and persisted during other seasons. GII.4-2009 variant was first detected in January 2010 and predominant in 2011-2012. However, it was rapidly displaced by GII.4-2012 variant, which emerged in May 2012 and substantially circulated in 2012-2013. CONCLUSIONS: The frequent emergence and rapid spread of GII.4 variants significantly affect the magnitude of sporadic NoV infections in children. Hence, to minimize the disease burden of NoV infections, GII.4 strains should be considered as a primary target for vaccine development against NoVs.

Simultaneous determination of nine UV filters and four preservatives in suncare products by high-performance liquid chromatography.

HPLC method for quantitative determination of four preservatives and nine UV filters worldwide authorized in commercial suncare product was developed and validated, and then 101 samples of commercial suncare products were analyzed for the UV filters and preservatives using the proposed method. The mobile phase was acetonitrile-water containing 0.5% acetic acid using a gradient elution at a flow rate of 0.9 mL/min and UV measurements were carried out at 320 nm for UV filters and 254 nm for preservatives. The correlation coefficients of each calibration curves were mostly higher than 0.999. The percent relative standard deviations (%RSD) ranged from 0.97% to 6.1% for five sample aliquots. The recoveries from the spiked solutions were 98-102%. 2-ethylhexyl-p-methoxycinnamate (EHMC) was detected in 96 of 101 commercial suncare products and the concentration was in the range of 3.08-8.16% and 18 samples were found to exceed the 7.5% which has been defined as the maximum allowed concentration in Korea. Methyl paraben was detected in 81 of 101 samples and the next-most often detected preservatives were propyl paraben (25), ethyl paraben (18), and butyl paraben (4). Three samples of 101 suncare products exceeded the maximum allowed concentration (i.e., 0.58-0.79%). The proposed HPLC method allows efficient and simultaneous analysis of preservatives and UV filters suitable for quality control assays of commercial suncare products.