• Food Science and Biotechnology
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• 제15권2호
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• pp.232-237
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• 2006

Bacillus cereus group comprising B. cereus, B. thuringiensis, and B. mycoides was differentiated by polymerase chain reaction (PCR) and colony morphology. Prevalence of B. cereus group in rice and distribution of enterotoxin genes were determined as possible food poisoning agents. PCR using primers targeted for gyrB and cry genes could distinguish B. thuringiensis from B. cereus, and B. mycoides was differentiated by rhizoid morphological characteristics on nutrient agar. Among 136 rice and their processed products, prevalence of B. cereus group was 40%. B. cereus group consisted of 54 B. cereus, 11 B. thuringiensis, and 1 B. mycoides. Major isolates were B. cereus, with B. thuringiensis detected up to 10% among edible rice tested. Five enterotoxin genes, hbl, nhe, bceT, entFM, and cytK, were broadly distributed among B. cereus group, especially in B. cereus and B. thuringiensis. Prevalence of B. cereus group in rice and enterotoxin distribution suggest B. thuringiensis and B. cereus are toxigenic strain that should be controlled in rice and its products.

• 대한미생물학회지
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• 제18권1호
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• pp.53-58
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• 1983

Enterotoxigenic E. coli is one of causative agents of the infantile diarrhea and traveler's diarrhea. A modified infant mouse assay(IMA) was developed for the detection of heat stable enterotoxin (ST) of E. coli isolated from diarrheal and control infants and assay system was established with using enterotoxin producing reference strains. The supernatant of the 24 hour-shaking culture of E. coli in Casamino Acid Yeast Extract Salt Broth(CYES-2) was ingested orally into the 2-4 day old ICR mice. After the mice were kept at $25^{\circ}C$ for 4 hours, they were sacrificed and the gut weight body weight ratio(GW/BW) was taken as the index of fluid accumulation induced by heat stable enterotoxin of E. coli. The results obtained were as follows; 1. The GW/BW responses of IMA tested with enterotoxin reference strains of E. coli(E. coli O148H28:$ST^+LT^+$, E. coli $O78H^-:ST^+LT^+$, E. coli O15H11:$ST^-LT^+$, E. coli O1H7:$ST^-LT^-$) appeared ta be ST dose-dependent, and not LT-dependent. From the dose-response curve, $25{\mu}l$ of culture supernatant was determined as test amount of the IMA. 2. Frequency distribution of IMA result from 643 strain of E. coli showed normal distribution at low GW/BW ratio and dispersed pattern at high GW/BW ratio. The GW/BW ratios of $0.056{\pm}0.004(mean{\pm}SD)$ of normal distribution which distributed from 0.044 to 0.068(P<0.01) was considered as ST negative. Thus the GW/BW ratio above 0.069 could be regarded as ST positive.

• 한국축산식품학회지
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• 제35권4호
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• pp.502-506
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• 2015

The aim of this study was to investigate the antimicrobial resistance profiles of and the enterotoxin gene distribution in 4 strains of Staphylococcus aureus (S10-2, S10-3, S12-2, and S13-2) isolated from 90 bulgogi samples. The S. aureus enterotoxin H gene (seh) was found in all the strains, while the S. aureus enterotoxin A gene (sea) was found only in 3 of the 4 strains. The S10-2 strain expressed a combination of enterotoxin genes - seg, seh, sei, sej, selm, and seln. The strains S10-2 and S13-2 were resistant to ampicillin and penicillin G, and all the isolated strains were resistant to tetracycline. The S10-2 strain was the only mecA-positive strain; it was also resistant to β-lactam antibiotics. Thus, genes encoding enterotoxin as well as those conferring antibiotic resistance were identified in the S. aureus strains isolated from pork bulgogi. These results represents the potential occurrence of MRSA in pork bulgogi, and the need for a monitoring system for pork bulgogi in order to prevent an outbreak of staphylococcal food poisoning.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2043-2048
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• 2015

Bacillus thuringiensis microbial insecticide products have been applied worldwide. Although a few cases of B. thuringiensis foodborne illness have been reported, little is known about the toxigenic properties of B. thuringiensis isolates. The aims of this study were to estimate the pathogenic potential of B. thuringiensis selected from microbial insecticide products, based on its possession of toxin genes and production of enterotoxins. Fifty-two B. thuringiensis strains selected from four kinds of microbial insecticide products were analyzed. PCR assay for detection of toxin genes and immunoassay for detection of enterotoxins were performed. The hemolysin BL complex as a major enterotoxin was produced by 17 (32.7%), whereas the non-hemolytic enterotoxin complex was detected in 1 (1.9%) of 52 B. thuringiensis strains. However, cytK, entFM, and ces genes were not detected in any of the tested B. thuringiensis strains. The potential risk of food poisoning by B. thuringiensis along with concerns over B. thuringiensis microbial insecticide products has gained attention recently. Thus, microbial insecticide products based on B. thuringiensis should be carefully controlled.

• 한국동물위생학회지
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• 제19권2호
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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.

• 대한수의학회지
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• 제53권4호
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• pp.199-205
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• 2013

Avian pathogenic Escherichia coli (APEC) is a causative agent for a number of extra intestinal diseases and account for significant losses to the poultry industry. Since protective immunity against APEC is largely directed to virulence antigens, we have individually expressed four different viulence antigens, papA, papG, IutA, and CS31A, using an attenuated Salmonella Typhimurium and a plasmid pBB244. Following oral immunization of mice with combination of two or four of these strains, serum IgG and mucosal IgA responses were elicited against each antigen represented in the mixture. The antigen-specific mucosal IgA responses were significantly higher in the group of mice immunized with the heat-labile Escherichia coli enterotoxin B subunit (LTB) strain than those in the group of mice immunized without the LTB strain. While, there was no significant difference between these two groups in antigen-specific serum IgG responses. The results showed that LTB could act as mucosal immune adjuvant. To assess the nature of immunity, the distribution of antigen-specific IgG isotypes was analyzed. All groups promoted Th1-type immunity as determined by the IgG2a/IgG1 ratio. Thus, our findings provided evidence that immunization with a combination of several vaccine strains is one of the strategies of developing effective vaccines against APEC.

• 한국식품위생안전성학회지
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• 제35권3호
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• pp.219-224
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• 2020

본 연구는 2018년 10월에서 2019년 9월까지 부산지역 유통 판매되고 있는 872건의 다양한 식품을 대상으로 B. cereus 오염도를 분석하였다. 총 872건 중 78건(8.9%)에서 B. cereus 검출되었으며 식품별 B. cereus 검출률은 김치·절임·조림·젓갈류에서 23.9%, 조미식품 19.4%, 바로 섭취가능한 농산물 10.5%, 조리식품 7.3%, 즉석섭취식품 5.6%, 신선편의식품 5.0%, 즉석조리식품 0.0% 순으로 분포하였으며 통계적으로 유의한 차이가 있었다. B. cereus 오염 수준은 불검출에서 최대 20,000 CFU/g로 평균 48 CFU/g였으며, 식품별 B.cereus 오염도에는 차이가 없었다. 78건의 검체에서 분리된 113주의 B. cereus의 독소 유전자 확인 시험을 수행하였다. 식품에서 분리된 113주를 대상으로 B. cereus 독소유전자 확인 결과 최소 1종류에서 최대 5종류의 독소 유전자가 검출되었으며 총 18개 profile로 분류되었다. 장독소 5종(Cytk-nheA-entFM-bceT-hblC)을 모두 보유한 경우가 34주(30.1%)로 가장 많았다.

• Animal Bioscience
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• 제34권4호
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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).

• 한국식품위생안전성학회지
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• 제14권4호
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• pp.327-332
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• 1999

1996년 3월부터 1998년 10월간에 경남지방 시판 냉장육 888건, 냉동포장육 222건 및 수입 냉동육 117건의 시료로부터 식중독관련 병원균의 분포와 혈청형을 조사하였다. 식중독균의 분리률은 Staphylocorcus aureus. Campylobarter jejuni/coli, Listeria monocytogenes 및 Salmonella spp 순으로 높았고, Escherichia coli O157:H7은 전시료를 통해서 분리되지 않았다. C. jejuni /coli는 냉장육에서 높은 오염률을 나타내고, 냉동포장육에서는 거의 분리되지 않는데 반해서 L. monocytogenes는 냉장육에 이해서 냉동포장 계육에서 높은 분리율을 나타낸 것은 매우 흥미로운 일이다. 분리균의 혈청형 분포는 Sta. aureus의 경우 대부분이 enterotoxin type C와 D였고, Salmonella spp는 돈육유래균에서 모두 A group이었으며, 계육유래균은 대부분 B와 D group이었다. L. monocytogenes는 계육유래균의 대부분이 type 1 이었고, type 4는 소수로 분리되었다.

• 대한미생물학회지
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• 제21권1호
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• pp.73-95
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• 1986

A total of 5,462 isolates suspicious of Salmonella, Shigella and E. coli which were isolated during 1983 to 1985 by 12 City Hygine Laboratories and General Hospital Laboratories were received and identified at the National Salmonella Center, Seoul, Korea. The result of identification of these strains were summarized as follows: 1. It was confirmed that the total organisms broke down into 2,014 strains of Salmonella 1,294 of which were S. typhi, 887 strains of Shigella and 2,561 strains of E. coli. 2. For seasonal distribution of enteric pathogens, July was the month with the highest out breaks of salmonellosis, May was the month of Shigellosis, and April was of the highest month it in the case of E. coli. 3. Salmonella typhi with the highest incidence of isolation was shown to belong to various phage types, especially with the strains detected in Seoul. M1 type was widely distributed all over the country, but the majority was E1 type in 1983. 4. For age distribution of patients, the 20-29 age group had the highest incidence of salmonellosis whileas the 1 to 9 age group had the highest incidence of Shigellosis. 5. For sexuly distribution of Salmonella and Shigella infections seemed to be relatively higher in the female than in the male. However, E. coli. had no relationship to both sex. 6. The antibiotic sensitivity patterns of S. typhi cultures showed a tendancy to be resistant to colistin, gentamycin, neomycin, tetracycline and streptomycin. 7. The isolates of S. paratyphi-A, S. typhimurium and S. enteritidis seemed to have a tendency of multiple drug resistance. 8. 93.9 percent of 1,568 E. coli strains showed negative reactions to the antisera of enteropathogenic E. coli and 15.6 percent of them produced a heat-labile enterotoxin, but positive reaction to the antisera was 6.1 percent and 11.6 percent of them producled the enterotoxin.