Kun-Ho Seo

Konkuk University, Sŏul, Seoul, South Korea

Are you Kun-Ho Seo?

Claim your profile

Publications (74)95.58 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Although cefoperazone is the most commonly used antibiotic in Campylobacter-selective media, the distribution of cefoperazone-resistant bacteria such as extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is increasing. Here we evaluated the potential of cephamycins for use as supplements to improve modified charcoal-cefoperazone-deoxycholate agar (mCCDA) by replacing cefoperazone with the same concentrations (32 mg/L) of cefotetan (modified charcoal-cefotetan-deoxycholate agar, mCCtDA) and cefoxitin (modified charcoal-cefoxitin-deoxycholate agar, mCCxDA). In chicken carcass rinse samples, the number of mCCDA plates detecting for Campylobacter (18/70, 26%) was significantly lower than that of mCCtDA (42/70, 60%) or mCCxDA plates (40/70, 57%). The number of mCCDA plates (70/70, 100%) that were contaminated with non-Campylobacter species was significantly higher than that of mCCtDA (20/70, 29%) or mCCxDA plates (21/70, 30%). The most common competing species identified using mCCDA were ESBL-producing E. coli, while Pseudomonas species frequently appeared on mCCtDA and mCCxDA.
    No preview · Article · Jan 2016
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, changes in the prevalence of Salmonella during the processing of broiler chicken carcasses were investigated. A total of 1040 fecal swabs and chicken carcasses samples were collected from 2 processing plants at the 4 stages of broiler processing, which included live birds in slaughter line, postevisceration/prewashing, postwashing/prechilling, and postchilling, respectively. The intraspecific biodiversity of the Salmonella isolates was determined using a DiversiLab automated repetitive sequence-based PCR (rep-PCR) system. In both plants, the prevalence of Salmonella increased considerably after evisceration (from 4.6% to 30.8%, P < 0.05) and decreased after washing (from 30.8% to 25.4%, P < 0.05). However, the chilling step had little effect on Salmonella prevalence (from 25.4% to 22.7%, P > 0.05). The most frequent Salmonella serovar in plant A was Infantis (35.8%), followed by Enteritidis (26.2%) and Montevideo (15.0%), while Montevideo (43.6%) and Enteritidis (35.9%) were most prevalent in plant B. A difference in the rep-PCR banding pattern was found to be related to the processing plant origin and serovar rather than sampling point or sampling day, although there were some exceptional strains.
    No preview · Article · Nov 2015 · Journal of Food Science
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study was undertaken to determine the prevalence of Salmonella in 100 chicken carcass samples from five integrated broiler operation brands in Korea. Serotypes, antibiotic resistance patterns, extended-spectrum β-lactamase (ESBL) genotype, and clonal divergence using multilocus sequence typing of the isolated strains were analyzed. A total of 42 chicken samples were contaminated with nontyphoidal Salmonella (NTS) isolates: 16 isolates (38%) were Salmonella Virchow, 9 (21%) were Salmonella Bareilly, and 8 (19%) were Salmonella Infantis. A multidrug resistance (MDR; resistant to more than three classes of antibiotics) phenotype was observed in 29% of the isolates, which were resistant to five or more classes of antibiotics. The dominant MDR type was resistance to classes of penicillin, cephalosporins, aminoglycosides, quinolones, and tetracyclines. All the MDR isolates were positive for ESBL producers, and all but one (with the CTX-M-1 genotype) had the CTX-M-15 genotype. Multilocus sequence typing of the isolates revealed ST16 as the dominant sequence type; Salmonella Virchow, Salmonella Infantis, and Salmonella Richmond were all ST16, indicating a close genetic relationship between these serovars. This is the first study in Korea showing the CTX-M-1 type of NTS and the prevalence of ESBL-producing strains among NTS isolated from retail chicken meat. Our findings suggest that MDR Salmonella contamination is widely prevalent in retail chicken meat, and consumption of inadequately cooked products could lead to dissemination of NTS, which is hazardous to human health.
    No preview · Article · Nov 2015 · Journal of food protection
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ready-to-eat (RTE) foods such as prepared vegetables are becoming an increasingly popular food choice. Since RTE vegetables are not commonly sterilized by heat treatment, contamination with foodborne pathogens such as Bacillus cereus (B. cereus) is a major concern. The objective of this study was to assess the quantitative prevalence and toxin gene profiles of B. cereus strains isolated from RTE vegetables. We found that 70 of the 145 (48%) tested retail vegetable salad and sprout samples were positive for B. cereus. The B. cereus isolates harbored at least one enterotoxin gene. The detection rates of nheABC, hblCDA, cytK, and entFM enterotoxin genes among all isolates were 97.1%, 100%, 81.4%, and 98.6%, respectively. No strain carried the emetic toxin genes. Only 4 strains (5.7%) from the 70 isolates were psychrotrophic and were able to grow at 7°C. All of the psychrotrophic isolates possessed at least 1 enterotoxin gene.
    No preview · Article · Sep 2015 · Foodborne Pathogens and Disease
  • [Show abstract] [Hide abstract]
    ABSTRACT: Kefir is a type of fermented milk containing lactic and acetic acid bacteria and yeast. In this study, we evaluated the antimicrobial activity of kefir supernatant against Cronobacter sakazakii in powdered infant formula (PIF). In a spot-on-lawn test, the growth of 20 C. sakazakii strains, including 10 clinical and 10 food isolates, was completely inhibited in the presence of kefir supernatant. Significant differences in the diameters of inhibition zones were observed upon treatment with kefir compared with the results for Lactobacillus kefiri and Candida kefyr culture supernatants or solutions of lactic and acetic acid and ethyl alcohol in the agar well diffusion test (P < 0.05). The addition of 100 μl of kefir supernatant to 1 ml of nutrient broth completely inhibited the growth of C. sakazakii, as evaluated by spectrophotometry. The antimicrobial activity of kefir supernatant in experimentally contaminated PIF was also tested; we found no viable C. sakazakii cells remaining in PIF rehydrated with 30% kefir supernatant solution for 1 h, demonstrating that the antimicrobial activity of kefir supernatant against C. sakazakii could be applied in real food samples.
    No preview · Article · Sep 2015 · Journal of food protection
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacillus cereus causing emetic and diarrheal type of food poisoning is widely distributed in nature and is therefore considered a major foodborne pathogen. There is a growing demand for fast, accurate, reliable and economic detection of potentially toxigenic B. cereus. To improve differential diagnosis of toxigenic B. cereus, a highly sensitive pentaplex RT-PCR high resolution melt curve assay was developed for simultaneous detection of 4 major enterotoxim genes (cytK, entFM, hblD, nheA) and emetic toxin gene (ces). The average melting temperatures (Tm) of PCR products were 72.2 �C(ces), 74.23 �C(cytK), 76.55 �C (nheA), 78.42 �C(entFM) and 81.90 (hblD). The multiplex assay was evaluated using 71 bacterial strains including 17 emetic B. cereus reference strains, 9 enterotoxic B. cereus reference strains, 4 B. cereus group members, 23 wild B. cereus strains, 18 non-target strains, and was further tested on artificially inoculated foods. The detection limit in food samples was approximately 103 CFU/g without enrichment and 101 CFU/g was observed following 7 h enrichment. The DNA intercalating dye SYTO9 used in this study generated high resolution melt curve peaks for the target strains and genes in which the peaks were sharp and easily distinguishable from each other. Thus, the developed multiplex real-time (RT) PCR approach can be a reliable tool for the identification of emetic and enterotoxic strains of B. cereus present in food and food-related samples.
    Full-text · Article · Aug 2015 · Food Control
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of flavonoid-rich wine grape seed flour, a byproduct of winemaking, on global adipose tissue gene expression and obesity-induced insulin resistance was assessed in high fat (HF) diet-induced obese (DIO) mice. DIO mice were fed HF diet supplemented with either partially defatted Chardonnay grape seed flour (ChrSd) or microcrystalline cellulose (MCC, control) for 5 weeks. ChrSd diet suppressed the HF diet-induced increase in total body, liver, and adipose tissue weights with a significant decrease in feed efficiency. ChrSd intake significantly lowered the 2-h insulin and glucose areas under the curve suggesting that ChrSd improves insulin sensitivity and glucose metabolism. Gene expression profiling analysis of adipose tissue from mice fed a ChrSd diet, by exon microarray and RT-PCR, revealed a down-regulation of genes related to oxidative stress, inflammation, immune response, protein carbonylation, and fatty acid synthesis. Conversely, genes related to the scavenging of free radicals, antioxidants, insulin sensitivity, and fatty acid oxidation, were up-regulated. Pathway analysis of microarray data identified genes related to innate immune response, inflammatory response, and infectious disease as being differentially regulated by the ChrSd diet. Thus, ChrSd ameliorates HF-induced obesity, insulin resistance, and glucose intolerance in DIO mice by modulating expression of genes in adipose tissue.
    No preview · Article · Aug 2015 · Journal of Functional Foods
  • [Show abstract] [Hide abstract]
    ABSTRACT: In South Korea, few reports have indicated the occurrence and characteristics of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in food-producing animals, particularly in poultry slaughterhouses. In this study, we investigated the occurrence and antibiotic resistance of ESBL-producing E. coli from whole chicken carcasses (n=156) and fecal samples (n=39) of chickens obtained from 2 slaughterhouses. Each sample enriched in buffered peptone water was cultured on MacConkey agar with 2 mg/L cefotaxime and ESBL agar. ESBL production and antibiotic susceptibility were determined using the Trek Diagnostics system. The ESBL genotypes were determined by polymerase chain reaction (PCR) using the blaSHV, blaTEM, and blaCTX-M gene sequences. Subtyping using a repetitive sequence-based PCR system (DiversiLab™) and multilocus sequence typing (MLST) were used to assess the interspecific biodiversity of isolates. Sixty-two ESBL-producing E. coli isolates were obtained from 156 samples (39.7%). No blaSHV genes were detected in any of the isolates, whereas all contained the blaTEM gene. Twenty-five strains (40.3%) harbored the CTX-M group 1 gene. The most prevalent MLST sequence type (ST) was ST 93 (14.5%), followed by ST 117 (9.7%) and ST 2303 (8.1%). This study reveals a high occurrence and β-lactams resistance rate of E. coli in fecal samples and whole chickens collected from slaughterhouses in South Korea.
    No preview · Article · Jul 2015 · Foodborne Pathogens and Disease
  • [Show abstract] [Hide abstract]
    ABSTRACT: Korean fermented soybean products, such as doenjang, kochujang, ssamjang, and cho-kochujang, can harbor foodborne pathogens such as Bacillus cereus sensu lato (B. cereus sensu lato). The aim of this study was to characterize the toxin gene profiles, biochemical characteristics, and antibiotic resistance patterns of B. cereus sensu lato strains isolated from Korean fermented soybean products. Eighty-eight samples of Korean fermented soybean products purchased from retails in Seoul were tested. Thirteen of 26 doenjang samples, 13 of 23 kochujang samples, 16 of 30 ssamjang samples, and 5 of 9 cho-kochujang samples were positive for B. cereus sensu lato strains. The contamination level of all positive samples did not exceed 4 log CFU/g of food (maximum levels of Korea Food Code). Eighty-seven B. cereus sensu lato strains were isolated from 47 positive samples, and all isolates carried at least one enterotoxin gene. The detection rates of hblCDA, nheABC, cytK, and entFM enterotoxin genes among all isolates were 34.5%, 98.9%, 57.5%, and 100%, respectively. Fifteen strains (17.2%) harbored the emetic toxin gene. Most strains tested positive for salicin fermentation (62.1%), starch hydrolysis (66.7%), hemolysis (98.9%), motility test (100%), and lecithinase production (96.6%). The B. cereus sensu lato strains were highly resistant to β-lactam antibiotics such as ampicillin, penicillin, cefepime, imipenem, and oxacillin. Although B. cereus sensu lato levels in Korean fermented soybean products did not exceed the maximum levels permitted in South Korea (<10(4) CFU/g), these results indicate that the bacterial isolates have the potential to cause diarrheal or emetic gastrointestinal diseases. © 2015 Institute of Food Technologists®
    No preview · Article · May 2015 · Journal of Food Science
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this investigation was to determine the prevalence and characteristics of extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae in ready-to-eat (RTE) vegetables. A total of 189 RTE vegetable samples (91 sprouts and 98 mixed salads) were collected in a retail market in South Korea from October 2012 to February 2013. The prevalence of ESBL-producing E. coli and K. pneumoniae was 10.1%. Of these, 94.7% were from the sprout samples. All isolates were resistant to cefotaxime, and many of the ESBL producers were also resistant to non-β-lactam antibiotics, including gentamicin, trimethoprim/sulfamethoxazole, and ciprofloxacin (73.7%, 63.2%, and 26.3% respectively). TEM-1, SHV-1, -2, -11, -12, -27, -28 and -61, and CTX-M-14, -15 and -55 β-lactamases were detected alone or in combination. The genetic platforms of all CTX-M producing isolates were ISEcp1-blaCTX-M-orf477 and ISEcp1-blaCTX-M-IS903 in CTX-M groups 1 and 9, respectively. To our knowledge, this is the first report of the prevalence and characterization of ESBL-producing E. coli and K. pneumoniae isolated from RTE vegetables. The results of this study indicate that RTE vegetables, sprouts, in particular, may play a role in spreading antimicrobial resistant bacteria and ESBL genes to humans. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · May 2015 · International journal of food microbiology

  • No preview · Article · Apr 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lactobacillus kefiranofaciens is an indicator microorganism for kefir and a key factor in kefir grain formation and kefiran production. We designed a novel real-time PCR primer and probe set, LKF_KU504, for the rapid detection of L. kefiranofaciens. In inclusivity and exclusivity tests, only 14 L. kefiranofaciens strains were positive among 61 microorganisms, indicating 100 % sensitivity and specificity. The LKF_KU504 set also differentiated kefir milk from 30 commercial nonkefir yogurts. The levels of L. kefiranofaciens in kefir grain and kefir milk were significantly different, indicating L. kefiranofaciens was more concentrated in kefir grain than in kefir milk.
    No preview · Article · Apr 2015 · Journal of food protection
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacillus cereus can cause emetic and diarrheal food poisoning. It is widespread in nature and therefore, considered a major foodborne pathogen. To develop a sensitive and reliable assay for detecting enterotoxin genes (nheA, entFM, hblD, cytK) and emetic toxin (ces), specific primers each targeting one individual gene were designed. Propidium monoazide (PMA) was coupled with the developed multiplex PCR (mPCR) for the detection of viable B. cereus. The inclusivity and exclusivity of the PMA-mPCR was confirmed using a panel of 44 strains including 17 emetic and 9 enterotoxic B. cereus reference strains and 18 non-target strains. The limit of detection (LOD) without PMA treatment in pure DNA was 2 pg/ reaction tube. The LOD of mPCR assay in pure heat-killed dead bacteria was 4.0 � 102 CFU/mL. Also, the LOD on the viable bacteria with or without PMA treatment was similar (3.8 � 102 CFU/mL) showing that the PMA treatment did not significantly decrease sensitivity. Finally, the newly developed PMA-mPCR successfully detected 4.8 � 103 and 3.6 � 103 CFU/g of viable B. cereus F4810/72 (emetic) and B. cereus ATCC 12480 (enterotoxic) reference strains, respectively, in food samples. Hence, this study combines PMA and mPCR to detect viable B. cereus with a wide range of toxin detection (5 toxins). Thus, the novel PMA-mPCR assay developed in this study is a rapid and efficient diagnostic tool for the monitoring of viable B. cereus in food samples and potentially other samples via appropriate DNA extraction.
    Full-text · Article · Mar 2015 · Food Control
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The emergence of antibiotic-resistant foodborne Salmonella has become a major public health problem. Consumption of undercooked poultry contaminated with Salmonella can induce food poisoning in humans. In this study, we investigated the occurrence and antibiotic resistance patterns of Salmonella spp. isolated from 120 chicken carcasses produced in 6 poultry slaughterhouses in South Korea. A total of 11 samples (9.2%) were found contaminated with Salmonella: 5 isolates were serotyped as Salmonella Bellevue strain (slaughterhouse C) and 6 isolates were serotyped as Salmonella Enteritidis strain (slaughterhouse E). Salmonella Bellevue isolates were resistant to five antibiotics (ampicillin, chloramphenicol, nalidixic acid, tetracycline, and trimethoprim/sulfamethoxazole), while Salmonella Enteritidis isolates were resistant to nine antibiotics (ampicillin, cefotaxime, ceftazidime, cefazolin, cephalothin, amikacin, nalidixic acid, streptomycin, and tetracycline). All cephalosporin-resistant Salmonella Enteritidis isolates exhibited the extended-spectrum β-lactamase (ESBL) phenotype and carried the gene encoding CTX-M-15, the most prevalent ESBL enzyme worldwide. Based on molecular subtyping performed using the automated rep-polymerase chain reaction (PCR) system (DiversiLab), the isolates showing ≥95 similarity in their rep-PCR banding patterns were classified into 5 pulsotypes. Given that cephalosporins are the drugs of choice for invasive Salmonella infections, the high incidence of ESBL-producing strains in chicken should emphasize the necessity of regular monitoring of the occurrence of antibiotic-resistant ESBL-positive Salmonella strains in poultry meat.
    Preview · Article · Feb 2015 · Foodborne Pathogens and Disease
  • [Show abstract] [Hide abstract]
    ABSTRACT: The relationship between the intestinal microbiota and the hypocholesterolemic and anti-obesity effects of whole grape seed flour from white and red winemaking was evaluated. Male Golden Syrian hamsters were fed a high-fat (HF) control diet, or HF diet supplemented with 10% partially defatted grape seed flours from either Chardonnay (ChrSd) or Cabernet Sauvignon (CabSd) grapes for three weeks. The numbers of total bacteria and relative abundances of Bifidobacterium spp., Lactobacillus spp., and Firmicutes in feces were significantly lower while the relative abundance of Bacteroides fragilis was greater than the control from feeding the ChrSd diet. The ratio of Firmicutes/Bacteroidetes (F/B) was lower in ChrSd diet. There were significantly positive correlations between Lactobacillus spp., ratio of F/B and plasma total- and LDL-cholesterol and liver weight. The reduction of Lactobacillus spp. by the ChrSd diet was accompanied by inhibition of Farnesoid X receptor (FXR) signaling in the intestine as expression of intestinal fibrablast growth factor (FGF)15, positively regulated by FXR, was decreased. Expression of CYP7A1, negatively regulated by FGF15, was up-regulated in the liver, indicating that alteration of the intestinal microbiota may regulate bile acid and lipid metabolism. These findings suggest that beneficial health effects of Chardonnay grape seed flour on HF-induced metabolic disease relate in part to modulation of intestinal microbiota and their metabolic processes.
    No preview · Article · Jan 2015 · Journal of Agricultural and Food Chemistry
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The identity of 45 Hanwo and 47 imported beef (non-Hanwoo) samples from USA and Australia were verified using the microsatellite (MS) marker and single nucleotide polymorphism (SNP) methods. Samples were collected from 19 supermarkets located in the city of Seoul and Gyeonggi province, South Korea, from 2009 to 2011. As a result, we obtained a 100% concordance rate between the MS and SNP methods for identifying Hanwoo and non-Hanwoo beef. The MS method presented a 95% higher individual discriminating value for Hanwoo (97.8%) than for non-Hanwoo (61.7%) beef. For further comparison of the MS and SNP methods, blood samples were collected and tested from 54 Hanwoo x Holstein crossbred cattle (first, second, and third generations). By using the SNP and MS methods, we correctly identified all of the first-generation crossbred cattle as non-Hanwoo; in addition, among the second and third generation crossbreds, the ratio identified as Hanwoo was 20% and 10%, respectively. The MS method used in our study provides more information, but requires sophisticated techniques during each experimental process. By contrast, the SNP method is simple and has a lower error rate. Our results suggest that the MS and SNP methods are useful for discriminating Hanwoo from non-Hanwoo breeds.
    Full-text · Article · Dec 2014 · Hangug chugsan sigpum haghoeji = Korean journal for food science of animal resources

  • No preview · Article · Dec 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Virus-like particles (VLPs) composed of the truncated capsid protein of swine hepatitis E virus (HEV) were developed and immune responses of mice immunized with the VLPs were evaluated. IgG titers specific for the capsid protein of swine HEV were significantly higher for all groups of mice immunized with the VLPs than those of the negative control mice. Splenocytes from mice immunized with the VLPs also produced significantly greater quantities of interferon (IFN)-γ than interleukin (IL)-4 and IL-10. These newly developed swine HEV VLPs have the capacity to induce antigen-specific antibody and IFN-γ production in immunized mice.
    Preview · Article · Dec 2014 · Journal of Veterinary Science
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chlorine bactericidal effects on Cronobacter vegetative cells and biofilms on conveyor belt chips were evaluated. Cronobacter vegetative cell isolates were inactivated after 10 min chlorine exposure (10 ppm). No efficacy difference was observed between pH-adjusted and pHunadjusted sodium hypochlorite solutions. The pH-adjusted solution was more effective at reducing the bacterial population in a biofilm. The number of cells in the biofilm on a Buna-N chip decreased by 3 log after exposure to 100 ppm of pH-adjusted chlorine and for PVC by 2.21 log after exposure to 400 ppm of pH-adjusted solution. The rate of biofilm reduction is dependent on the composition of the conveyor belt, concentration of chlorine, and pH of the chlorine solution.
    No preview · Article · Dec 2014 · Food science and biotechnology
  • Source
    Fereidoun Forghani · Kun-Ho Seo · Deog-Hwan Oh
    [Show abstract] [Hide abstract]
    ABSTRACT: A multiplex PCR assay for the rapid detection of B. cereus group, enterotoxic and emetic strains was developed. A panel of emetic and enterotoxic reference strains, B. cereus group members and non-target strains were used for the evaluation of the assay. Verification of PCR results on pure culture and inoculated foods successfully confirmed the specificity of approach for detection of target genes for B. cereus group (groEL), diarrheal (cytK, nheA, hblC, entFM) and emetic strains (CER). The sensitivity of approach was satisfying in pure culture as 20 pg of DNA per reaction tube. Artificial contamination of seven different food matrices with distinct bacterial counts revealed a minimum detection limit of 103 cfu/g in food samples. The detection limits were improved to approximately 101 cfu/g after 7 h enrichment. Natural contamination in rice and kimbab as well as environmental samples (soil, cow feces) was studied. The incidence of B. cereus was 63.88 and 38.88% in rice and kimbab, and 84.61 and 69.23% in soil and feces, respectively. To the best of our knowledge, this is the first time that an assay for simultaneous detection of B. cereus group, emetic and enterotoxic strains with such a wide range of detection target genes in food and environmental samples has been described.
    Full-text · Article · Nov 2014 · African journal of microbiology research