• 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.

• Journal of Food Hygiene and Safety
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• v.18 no.2
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• pp.79-86
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• 2003

Most of food poisoning is frequently raised from mass catering. Especially, staphylococci takes the large part of pathogenic agents which are related to the hygienic condition. Among total 98 samples, four staphylococci were isolated from food service environment such as drinking water (A), hands (D), refrigerator and apron (E) of 5 elementary school (A, B, C, D, E) in Gyeongnam Province. These isolated strains are characterized as 1 MRCNS (Methicilline Resistant Coagulase Negative Staphylococcus aureus) and 3 MSCPS (Methicilline Sensitive Coagulase positive Staphylococcus aureus). Also, production of enterotoxin B (sob gene) were examined by PCR which has known as a big problem because of their temperature resistance. Hence, PCR was performed on isolated 4 staphylococci. The all 4 isolated Staphylococcus aureus have 477 bp of seb gene. Antibiotics susceptibility test was completed on PCR detected strains. All strains were fully resistance to ampicillin and penicillin. The drinking water of A place has resistance to oxacilline, therefore this strain turned out to be MRSA (Methicilline Resistant Staphylococcus Aureus).

• The Journal of the Korean Society for Microbiology
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• v.19 no.1
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• pp.65-71
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• 1984

The author attempted serological typing with the slide agglutination and the production of heat-labile enterotoxin (LT) and heat-stable enterotoxin (ST) by the enterotoxingenic eschenchia coli 446 strains isolated from diarrheal patients. The enterotoxingenic E.coli, producing LT and/or St, were detected by use of assays in the reversed passive hemagglutination(RPHA) and the suckling mouse method. The results obstained were as follows: 1. Of 446 strains isolated, 88 strains(19.73%) produced LT, while 224 strains(50.22%) produced ST, 134(30.05%) produced both LT-ST simultaneously. Serological typing were typed into 06, 08, 020, 025, 027, 0126, 0148 and 0159. Serotype 06 had the highest incidence of 26.46% followed by 0148(18.16%), 027(14.57%); 025(10.99%), 0159(4.03%), 0126(3.59%), 020(1.12%) and 08(0.45%). 2. Serotype 06, 08 and 025 almost always produced both LT and ST, whereas serotypes 020, 027 and 0148 almost always produced only ST. And serotypes 06, 025, 0126 and 0159 almost always produced LT or ST. 3. Of 134 LT-ST positive strains, 115 strains were serotype 06, 3 strains were 025, 2 strains were 08, and 14 strains were 0 untypable. 4. Of 224 ST positive strains, 65 strains were serotype 027, 81 strains were 0148, 16 strains were 0159, and 42 strains were 0 untypable. 5. Of 88 LT positive strains, 45 strains were serotype 025, 5 strains were 0126, 2 strains were 0159, and 42 strains were 0 untypable.

• Korean Journal of Veterinary Service
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• v.19 no.2
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• pp.139-153
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• 1996

Porcine E coli infection is a disease caused by Enterotoxin produced by Enterotoxigenic Escherichia coli(ETEC). Enteric colibacillosis has become an economically important disease in pigs as a result of increasing intensification of farrowing management. The present study undertaken to obtain the antibiotic sensitivity and distribution of serogroups and pili producibility test of ETEC from E. coli isolates in Chonnam. The results obtained were as follows. 1. A total of 71 isolates identified as E, coli employing IMViC system from rectal specimens of 54 piglets with diarrhea. 2. In antibiotic sensitivity test, isolates showed high sensitivity to AN, CM, Fox, GM, but resistance to EM, NA TC. 3. The distribution of 25 Isolates of serogroups were 0141:K85(11.3%), 08:K87(8.5%), 064:K (5.6%), 0138:K8l (4.2%), 0139 :K82(2.8%), 0157:K88ac(1.4%) and 0149:K9l (1.4%). 4. MRHA of guinea pig erythrocytes was detected in 8 out of 25OK serotypes and 9 out of 46 unidentified serotypes. MRHA titers of serotypes showed from 64 to 128 in 0141: K85, 2 in 0138:K8l and no titers in 0139:K82. 5. The production of heat labile enterotoxin of ETEC was detect 39 out of 52 isolates showed $\beta$-hemolysin, 7 out of 52 isolates showed ${\gamma}$-hemolysin and 6 out of 52 isolates showed ${\gamma}$-hemolysin by $GM_1$ganglioside ELISA. The distribution of LT toxin were in 12 isolate showed $\beta$-hemolysin, 2 isolates showed ${\alpha}$-hemolysin and 3 isolates showed ${\gamma}$-hemolysin in 25 OK serotypes.

• Animal Bioscience
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• v.34 no.4
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• pp.734-742
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• 2021

Objective: The present study aimed to investigate the occurrence and species of coagulase-positive staphylococci (CoPS) and coagulase-negative staphylococci (CoNS) in retail pork meat samples collected during nationwide monitoring. The staphylococcal isolates were characterized for antimicrobial and zinc chloride resistance and enterotoxigenic potential. Methods: A total of 260 pre-packaged pork meat samples were collected from 35 retail markets in 8 provinces in Korea for isolation of staphylococci. Antimicrobial and zinc chloride resistance phenotypes, and genes associated with the resistance phenotypes were determined on the isolates. Furthermore, the presence and distribution of 19 staphylococcal enterotoxin (SE) genes and enterotoxin-like genes among the pork-associated staphylococci were determined by multiplex polymerase chain reaction-based assays using the specific primer sets. Results: A total of 29 staphylococcal strains (29/260, 11.1%) were isolated from samples of retail pork meat, 24 (83%) of which were CoNS. The four CoNS species identified were S. saprophyticus (n = 16, 55%), S. sciuri (n = 3, 10%), S. warneri (n = 3, 10%), and S. epidermidis (n = 2, 7%). Among the 29 isolates, four methicillin-resistant CoNS (MR-CoNS; three S. sciuri and one S. epidermidis) and one methicillin-resistant CoPS (MR-CoPS; one S. aureus) were identified. In addition, a relatively high level of tetracycline (TET) resistance (52%) was confirmed in CoNS, along with a predominant distribution of tet(K). The most prevalent SEs were sep (45%), and sen (28%), which were carried by 81% of S. saprophyticus. Conclusion: These findings suggest that CoNS, especially S. saprophyticus strains, in raw pork meat could be a potential risk factor for staphylococcal food poisoning (SFP), and therefore, requires further investigation to elucidate the role of SEls in SFP and virulence of the pathogen. Our results also suggest that CoNS from raw pork meat may act as a source for transmission of antimicrobial resistance genes such as staphylococcal cassette chromosome mec and tet(K).

• Korean Journal of Veterinary Research
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• v.41 no.2
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• pp.177-188
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• 2001

Mastitis is one of the most significant cause of economic loss to the dairy industry. Especially, Staphylococcus aureus is a major contagious mastitis-causing pathogen in dairy cattle. Because of its high transmission rate and resistance to antibiotic therapy, staphylococcal mastitis presents a constant threat to the dairy industry. Staphylococcal enterotoxin C(SEC) produced by S aureus has been known as one of superantigens which are able to stimulate a large proportion of T lymphocytes independently of their antigenic specificity. In this experiment, we have conducted preliminary studies with mice and lactating cows to evaluate the immunogenicity and safety of the experimental vaccine consists of SEC mutant antigen on controlling the bovine mastitis associated with S aureus infections. The average value of somatic cell counts in quarter milk, isolation rate of S aureus were consistently decreased in SEC-SER vaccinated groups, whereas antibody titers were highly increased in SEC-SER vaccinated groups. Peripheral blood were also collected from the lactating cows to determine the proportion of leukocyte subpopulation associated with humoral immunity(HI) and cell mediated immunity(CMI). Proportion of leukocyte subpopulation expressing $BoCD2^+$(total T lymphocyte), $BoCD4^+$(T helper cell), $BoCD8^+$(T cytotoxic/suppressor cell) and NonT/NonB lymphocyte which are involved in CMI in SEC-SER vaccinated groups were decreased for the initial stage after first vaccination and then increased from ten weeks after first vaccination maintaining elevated level till 14 weeks after vaccination. In contrast, proportion of monocyte, MHC class II and B lymphocyte which are associated with the production of primary immune response in SEC-SER vaccinated groups were increased for the initial period and then decreased from ten weeks after first vaccination. We present evidence that vaccination of SEC-SER mutant antigen in lactating cows induced a significant proliferation of bovine T lymphocytes. These results suggest that SEC-SER mutant antigen used in this experiment might be one of potential immunogen in developing innovative vaccine against bovine IMI associated with S aureus. Additional challenge trials should be carried out to evaluate substantial protection against S aureus under the commercial farm conditions.

• Journal of Life Science
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• v.21 no.2
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• pp.257-264
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• 2011

Seventy five methicillin- resistant Staphylococcus aureus (MRSA) strains and 24 methicillin- susceptible S. aureus (MSSA) were isolated from clinical specimens obtained from a hospital in Suncheon, Jeonnam province, Korea, from July to December, 2009. Antibiotic resistance was determined using the disc diffusion method. Genes encoding enterotoxin (SE), toxic shock syndrome toxin-1 (TSST-1), exfoliative toxin (ET) and Panton-Valentine leukocidin (PVL) were detected by multiplex PCR-mediated amplification using specific primers. Sixty (80%) MRSA isolates possessed either one or more toxin genes and the most common pattern that coexisted in MRSA was seb, sec, seg, sei and tst (22.7%) followed by coexistence of sec, seg, sei and tst genes (18.7%). Gene pvl encoding leukocidin was not found. Significant correlation between the production of sec, seg, sei and tst genes was found. MRSAs were resistant to erythromycin (89% of the isolates), gentamicin (70.7%), ciprofloxacin (69.3%), clindamycin (61.3%) and tetracycline (58.7%), while MSSAs were susceptible to the antibiotics with the exception of erythromycin. Toxin genes seb, sec and tst were related to the tetracycline resistance of MRSA.

• The Journal of the Korean Society for Microbiology
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• v.34 no.6
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• pp.573-582
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• 1999

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. The purpose of this study was to investigate the effect of lipopolysaccharide (LPS), Staphylococcus enterotoxin B (SEB), and Mycoplasma lysates on regulation of IL-6 and IL-8 production by human nasal fibroblasts. Primary cultured cells were incubated with LPS ($1.0\;{\mu}g/ml$) from E.coli, SEB ($1.0\;{\mu}g/ml$) from S.aureus, or Mycoplasma lysates (M.pneumoniae, Mp; M. fermentans, Mf; M. hominis, Mh, each $1.0\;{\mu}g/ml$). The culture supernatants were collected at 2, 6, and 24 hr and assessed for IL-6 and IL-8 production by enzyme-linked immunosorbent assay. The production of IL-6 in the culture supernatant was downregulated by LPS, SEB, or Mycoplasma lysates. But IL-6 was upregulated by mixed exposure with Mp+LPS (2 hr), Mp+LPS+SEB (24 hr), Mf+LPS (24 hr), Mf+LPS+SEB (2 hr), Mh+LPS (24 hr), Mh+SEB (24 hr), or Mh+LPS+SEB (24 hr). The production of IL-8 in the culture supernatant was similar to that of IL-6 by same stimulants. But IL-8 was upregulated by mixed exposure with Mf+LPS+SEB (2 hr), Mh+LPS (24 hr), Mh+ SEB (24 hr), or Mh+LPS+SEB (24 hr). These studies show that costimulation of LPS or SEB with Mycoplasma whole cell lysates upregulates the production of IL-6 and IL-8.

• Journal of Microbiology
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• v.38 no.1
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• pp.1-7
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• 2000

Eight strains of Aeromonas hydrophila isolated from diseased trout in Korea were characterized and compared with an American type strain by various methods including biochemical and physiological tests, PCR, randomly amplified polymorphic DNA (RAPD), plasmid profiling, and gel electrophoresis of total, membrane, and extracellular proteins. Virulence factors such as surface array proteins, cytotoxin, hemolysin, haemagglutinin, and protease were also investigated. The Korean strains showed heterogeneity in Iysine decarboxylase production, utilization of various carbon sources, and production of acetoin. Five strains had the same profiles of total and membrane proteins. Six strains haemagglutinated with trout red blood cells (RBCs) which was inhibited by fucose, galactose, and mannose, except for No. 1 where haemagglutination was inhibited by only galactose and mannose, but not by fucose. Four isolates haemagglutinated with human RBCs which was inhibited by fucose and mannose yet not by galactose. The type strain haemagglutinated only with trout RBCs which was inhibited by fucose, galactose, and mannose. Every isolate secreted protease, hemolysin, cytotoxin, and siderophore, but no enterotoxin. Results showed that the Korean isolates, except for No.7, had very different biochemical and molecular characteristics from those of the American type strain.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.4
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• pp.332-344
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• 1999

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. Interleukin-6 (IL-6) is involved in the final differentiation of B cells into antibody-producing cells. Interleukin-8 (IL-8) is a neutrophil chemotactic factor that plays an important role in the recruitment of neutrophil to inflammatory loci. Inflammatory mediators by cells in the gingiva have been implicated in the initiation and progression of periodontitis and oral infection. The purpose of this study was conducted to investigate the effect of lipopolysaccharide (LPS), staphylococcus enterotoxin B (SEB) on production of IL-6 and IL-8 by human gingival and facial dermal fibroblasts. Primary cultured human gingival and facial dermal fibroblasts were incubated with LPS (0.01, 0.1, $1.0{\mu}g/ml$), SEB (0.01, 0.1, $1.0{\mu}g/ml$) or LPS $(0.1{\mu}g/ml)$ plus SEB $(0.1{\mu}g/ml)$. Culture supernatants were collected at 24, 48, and 72 hrs and assessed for IL-6 and IL-8 production by enzyme-linked immunosorbent assay. IL-6 production in gingival fibroblasts stimulated with LPS was higher than that with SEB. IL-6 production by double exposure with LPS plus SEB was amplified in comparison with single exposure of LPS or SEB. IL-6 production in facial dermal fibroblasts was increased only by stimulation with a high concentration of LPS $(1.0{\mu}g/ml)$. Its production in facial dermal fibroblasts by exposure with SEB was decreased in comparison with control, nontreated cells. Therefore, gingival fibroblasts showed higher sensitivity than facial dermal fibroblasts in response to low concentration of LPS. Also, IL-6 production by double exposure with LPS plus SEB was amplified in comparison with single exposure of LPS or SEB. IL-8 production in gingival fibroblasts was enhanced greatly only by stimulation of high concentration of LPS $(1.0{\mu}g/ml)$. That by exposure with SEB was increased only in 24 hrs cultivation. IL-8 production by double exposure with LPS plus SEB was amplified in comparison with single exposure of LPS or SEB. IL-8 production in facial dermal fibroblasts was decreased by LPS and increased only in 48 hrs cultivation by SEB. IL-8 production by double exposure with LPS plus SEB was enhanced only in 48 hrs cultivation in comparison with single exposure of LPS or SEB. therefore, IL-6 and IL-8 production were released at various quantities according to bacterial toxin applied and site of fibroblast harvested. These results suggest that gingival fibroblasts may be concerned with IL-6 and IL-8 related inflammatory response more than facial dermal fibroblasts.