• Food Science of Animal Resources
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• v.33 no.3
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• pp.403-410
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• 2013

This study was performed to evaluate the microbiological contamination level of raw beef from retail markets in Seoul, Korea. The sampling and laboratory test were performed according to the procedure of "Standard for processing and ingredients specification of livestock product" and "Korean food code". Enterotoxin of Staphylococcus aureus isolates were detected using VIDAS$^{(R)}$ and PCR-based methods. Listeria monocytogenes serotyping and genotyping were carried out using Listeria antisera and L. monocytogenes Fingerprinting kit, respectively. A total of 48 samples were collected from 16 retail markets (butcher's shop: 5, department store: 6, supermarket: 5) in 2011. The level of total bacteria counts in the butcher's shop, department store and supermarket were $4.4{\times}10^3$ CFU/g, $3.9{\times}10^5$ CFU/g and $1.0{\times}10^4$ CFU/g, respectively. The concentrations of Escherichia coli of these three retail markets were $6.4{\times}10$ CFU/g, 7.6 CFU/g and $2.0{\times}10$ CFU/g, respectively. Salmonella species was not detected on all samples. However, S. aureus was isolated in the 3 samples (6.25%) from each type of three retail markets. L. monocytogenes was isolated in the 4 samples (8.3%) from department stores. The level of contamination of these foodborne bacteria was less than 100 CFU/g. The enterotoxin-encoding genes of S. aureus isolates were sea, seh, sei and sep gene. The gene similarity of L. monocytogenes isolated from two retail markets by Rep-PCR showed 57.8-98.1% and 68.1-98.1%, respectively. These results suggest that the HACCP guideline for environmental control in slaughterhouse and retail markets should be provided to prevent cross contamination and manage foodborne pathogens such as L. monocytogenes and S. aureus.

• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.207-211
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• 2019

Mass mortality in commercially cultured Amur catfish (Silurus asotus), showing symptoms of dermal ulcerations, occurred on a private farm in Mar 2019 in Korea. β-hemolytic bacteria were isolated from the ulcers and kidneys of the fish and identified as Aeromonas veronii. The isolate was resistant to tetracycline and possessed cytotoxic heat-labile enterotoxin (aerolysin/hemolysin). We investigated the genetic determinants associated with tetracycline resistance, and the isolate has been confirmed to simultaneously possess tetA and tetE genes. This is the first report on the occurrence of tetracycline-resistant A. veronii infection related to mass mortality in commercially cultured Amur catfish in Korea.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.553-558
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• 1998

Using the previous established multiplex PCR (mPCR), the presence of six kinds of staphylococcal superantigen (SAg) genes was investigated for nineteen Staphylococcus aureus isolates from the commercialized meat sources. As a result, only one isolate from pork among 19 S aureus isolates (5.3%) was confirmed as a potential SAg producer and harbored sec gene. The results in this study suggest that meat may not be major contagion of staphylococcal food poisoning (SFP) in Korea and that staphylococcal enterotoxin type C may be associated with the disease. Also, the mPCR method in this study can be a useful genotypic method which can overcome the typical disadvantages of conventional antibody-based methods due to antigenic homology, and furthur survey on food-borne S aureus isolates can provide the important epidemiological data for SFP in Korea.

• Journal of Dairy Science and Biotechnology
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• v.32 no.2
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• pp.101-104
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• 2014

Food safety is a global health goal, and food-borne disease are a significant public health threat throughout the world. Dairy products are susceptible to contamination through a wide variety of physical, microbial, and chemical hazards. Risks of microbiological hazards are of immediate and serious concern to human health. Milk was inoculated with Bacillus cereus and stored at 10, 15, 20, and $30^{\circ}C$ for 7 days. We monitored the effect of the temperature on growth rate and variance of toxin production. The growth rate of B. cereus was suppressed in low temperature. We confirmed that the growth rate and the toxin production were accelerated when the storage temperature was increased. B. cereus began to produce toxins when the number of bacteria was higher than $10^7CFU/mL$. Therefore, managing the storage temperature of milk is important to inhibit the growth and the toxin production of B. cereus.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.125-130
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• 1987

The role of enteropathogenic Escherichia coli(EPEC) was evaluated in a group of children with endemic diarrhea admitted to Hanyang University Hospital in Seoul, Korea. EPEC was detected in fecal samples of 23% of 100 cases and 4.5% of 44 concurrent control children. The most commonly isolated EPBC strains were serogroups $O_{18a}O_{18c}:K_{77},\;O_{86a}:K_{61},\;O_{119}:K_{69},\;and\;O_{128}:K_{70}$. On testing for enterotoxin production, 6(26%) strains were isolated from 17% of the 100 diarrheal children and in 4.5% of the 44 well controls(P<0.05). Our study supports the concept that EPEC may be an important cause of endemic diarrheas in Korea.

• Korean Journal of Veterinary Research
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• v.26 no.1
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• pp.69-77
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• 1986

The purpose of this study was the examination for presence of K99 antigen (K99), enterotoxigenicity, 0-groups, colicin and antibiotic susceptibility among E. coil isolated from calves and cows. A total of 49(18.7%) among 262 strains, isolated from 30(26.5%) out of 113 calves and cows, possesed K99, and thirty three of 49 $K99^+$ strains produced ST. Of the strains of diarrheal calf origin which less than 15 days old, a high correlation was observed between enterotoxigenic ability and K99: 92.3% of the $K99^+$ strains produced heat stable enterotoxin(ST). In O group typing of 33 $ST^+$ strains, they belonged to O20(48.4%), O8(9.1%), O9(6.1%), O139(6.1%), O149(6.1%), O101(3.0%), O115(3.0%), except six which were untypable or autoagglutinable. Of 262 E. coil isolates, 30 strains(13.3%) produced colicin and K99 were detected in 6 strains. One hundred eighty eight strains(71.8%) of 262 E. coil isolates were resistance to ampicillin, chloramphenicol, gentamicin, kanamycin, streptomycin, tetracycline, alone or in combination thereof. One hundred and fourteen(60.6%) out of 188 drug resistance strains carried R factor($R^+$) which were transferable to the recipients by conjugation. Sixty five $R^+$ strains(57.0%) carried thermo-sensitive R plasmid.

• The Journal of Korean Society of Virology
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• v.30 no.1
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• pp.1-10
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• 2000

The nonstructural protein NSP4, encoded by gene 10 of rotavirus, has been shown to playa role in viral assembly and known to be an enterotoxin, causing diarrhea in mouse pups. NSP4 gene was cloned from CBNU-2 (virulent bovine rotavirus/diarrheic fecal sample) and CBNU-1 (cell-culture adapted bovine rotavirus/isolated from CBNU-2 and 75 times passaged on MA104 cells), respectively, by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequenced and compared. The sequence data indicated that the NSP4 genes of bovine rotavirus (BRV) were 751 bases in length and encoded one open reading frame of 175 amino acids beginning at base 42 and terminating at base 569. Differences in nucleotide sequence between CBNU-2 and CBNU-1 were observed at 6 positions (base 274, 296, 391, 394, 396 and 579). NSP4 gene of BRV exhibited a high degree of nucleotide (90% and 94%) and amino acid sequence (91% and 97%) homology with those of SA11 and UK but a low degree of nucleotide (77% and 79%) and amino acids sequence (81% and 85%) homology with those of Wa and OSU.

• Journal of Dairy Science and Biotechnology
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• v.32 no.2
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• pp.105-109
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• 2014

Food borne pathogens are a growing concern for human health and food safety throughout the world. Milk and dairy products are commonly associated with spoilage or contamination from a wide variety of physical, microbial, and chemical hazards. Milk was inoculated with Staphylococcus aureus and stored at 5, 10, 15, 25, and $35^{\circ}C$ for 7 days, and we monitored the growth change and the variance of toxin production. The growth rate of S. aureus was suppressed in low temperature. We confirmed that growth rate and toxin production were accelerated when the storage temperature was increased. S. aureus began to produce toxins when the number of bacteria was higher than $10^5CFU/mL$. Therefore, managing the storage temperature of milk is important to inhibit the growth and the toxin production of S. aureus.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.543-552
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• 2020

For efficient prevention and treatment of enteric colibacillosis, understanding about latest virulence factors and antimicrobial resistance of Escherichia coli is essentially needed. The aim of this study was to survey antimicrobial resistance and determine the prevalence of fimbriae and enterotoxin genes among 118 pathogenic E. coli isolates obtained from Korean pigs with diarrhea between 2016 and 2017. The genes for the toxins and adhesins were amplified by polymerase chain reaction (PCR). The susceptibility of the E. coli isolates to antimicrobials were tested using the standard Kirby-Bauer disk diffusion method. The most prevalent fimbrial antigen was F18 (40.7%), followed by F4 (16.9%), and the most prevalent combinations of toxin genes were Stx2e (21.2%), STb:EAST-1 (19.5%), and STa:STb (16.9%), respectively. Among the pathotypes, enterotoxigenic E. coli (ETEC) was the most predominant (67.8%), followed by Shiga-toxin producing E. coli (STEC, 23.7%). We confirmed high resistance rates to chloramphenicol (88.1%), tetracycline (86.4%), streptomycin (86.4%), and ampicillin (86.4%). And the majorities of isolates (90.7%) showed multi-drug resistance which means having resistance to 3 or more subclasses of antimicrobials. Results of this study can be a source of valuable data for investigating the epidemiology of and control measures for enteric colibacillosis in Korean piggeries.

• Journal of environmental and Sanitary engineering
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• v.20 no.1 s.55
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• pp.23-31
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• 2005

On the purpose of epidemiological survey relate to food poisoning, a total of 114 samples of different salads collected from fast food Restaurants in Gyeonggi-do were for the presence of pathogenic microorganisms. Microbial assessment of salads revealed that TPC($1.1\times10\;\~\;8.4\times10^{5}\;CFU/g$) and coliforms($0\~5.4\times10^{4}\;CFU/g$) exceeded the standards by Solberg et al. ($TPC:10^{5}\;CFU/g,\;coliforms:10^{2}\;CFU/g$). Two pathogenic bacteria were isolated from salad samples, and identified by biochemical methods, including API identification systems. Isolates from PALCAM agar and MYP agar media were in 98.6, $99.8\%$ agreements with Listeria monocytogenes, Bacillus cereus at the species level, respectively. All 7 strains of Bacillus cereus isolates produced enterotoxin as revealed with CRET-RPLA.