살모넬라균은 가장 대표적인 수인성·식품매개질환 중 하 나이며 전 세계적으로 인간 위장염, 설사 질환의 가장 흔 한 원인이 되는 병원체이다. 식품 및 환경 검체, 식중독 또는 설사 환자로부터 분리한 살모넬라균의 혈청형, vitek2 를 이용한 항생제 내성검사, PFGE를 이용한 유전적 상관 관계를 조사하였다. 2020년부터 2023년까지 제주도의 식 품 또는 환경 검체에서 26주와 인체검체에서 313주로 총 339주가 분리되었다. 월별로 분리된 살모넬라균은 3월부 터 서서히 증가하여 8월에 가장 많이 살모넬라균을 분리 되었다. 환자로부터 분리된 살모넬라균은 성별에 따른 유 의미한 차이가 없었다. 그러나 살모넬라균은 70세 이상의 사람들에게서 가장 많이 분리되었고, 10-19세 사이의 사 람들에게서 가장 적게 분리되었다. 식품 및 환경 검체에 서 분리된 살모넬라균은 8개 혈청형이 있었으며, 주요 혈 청형은 S. Bareilly (26.9%), S. Rissen (23.1%), S. Thompson (19.3%) 순으로 확인되었다. 또한, 인체검체로 부터 분리된 살모넬라균은 27개 혈청형이 있었으며, 주요 혈청형은 S. Bareilly (31.0%), S. Typhimurium (24.6%), S. Enteritidis (11.5%) 순으로 확인되었다. 집단식중독의 원인이 되었던 살모넬라균 혈청형은 S. Bareilly, S. Enteritidis, S. Thompson이 있었다. 항생제 내성 검사 결과에서는 다양 한 항생제에 대한 내성이 나타났으며, 일부 살모넬라균에 서는 다제내성이 나타났다. 살모넬라균은 17개의 혈청형 에 따라 다양한 유전적 상관관계를 보여주었다. 이러한 결 과는 살모넬라균의 유행을 예측하고, 과학적 근거를 제공 함으로써 역학조사의 기초자료로 활용될 수 있을 것으로 사료된다.

Salmonella spp. 11 strains에 대해 저온 열처리(50oC) 3, 6, 9분 후 MIC값을 측정하여 항생제 내성을 알아보았다. Chloramphenicol에 대해 대조군과 열처리한 strains 대부분 에서 감수성(S)이 있는 것으로 나타났고, 열처리한 strains 의 MIC값은 대조군과 비교하였을 때 유지되거나 감소하 였다. Ciprofloxacin에 대해 대조군과 열처리한 strains는 대 부분 감수성(S)이 있거나 중간(I)을 나타냈다. Tetracycline 은 모든 strains에서 감수성(S)이 있는 것으로 나타났으며, S. Gaminara BAA 711에 대해 열처리 후 MIC값이 증가 하였다. Gentamicin에 대해 대조군 strains들에서 감수성을 나타낸 strains가 3 strains, 중간을 나타낸 strains 2 strains, 내성을 가진 strains가 6 strains였으며, 이 중 S. Heidelberg ATCC 8326는 MIC값을 측정했을 때 대조군에서 MIC값 이 8 μg/mL로 MIC break point가 중간이었으나, 3분과 9 분 열처리 후 MIC값이 16 μg/mL로 증가하여 break point 가 내성을 나타냈다. 본 실험결과 Salmonella spp. 11 strains 에 대해서 저온 열처리 후 열내성 효과에 의한 항생제 내성을 알아봤을 때 ciprofloxacin에서 S. Montevideo BAA 710을 3, 6분 열처리한 경우, gentamicin에서 S. Enteritidis 109 D1을 3분 처리한 경우와 S. Heidelberg ATCC 8326 을 3, 9분 처리한 경우, tetracycline에서 S. Gaminara BAA 711을 6, 9분 처리한 경우 MIC값이 증가하였다. 후속 연 구를 통해 Salmonella spp. strains에 대해 열처리 후 열내 성 효과를 나타내는 병원성 유전자의 특성에 대한 지속적 인 연구가 필요하다.

정부의 안전 농식품 안정 공급 정책에 따라 농식품 안전성 검사 수요가 증가하고 있으며, 현장에서 농식품의 안전성을 신속하게 검사할 수 있는 기술의 필요성이 커지고 있다. 대표적인 농식품 안전성 위해요소인 식중독균의 표준 검사 방법은 시간, 노력, 비용이 많이 소요되기 때문에 PCR이나 바이오센서와 같은 새로운 신속검사 기술에 대한 관심이 높아지고 있다. 많은 시료를 빠른 시간에 검사하는 광학기술은 농식품 품질 판정에 많이 활용되어 왔으나, 농식품 안전성을 검사하는 도구로서의 연구는 제한적으로 진행되어져 왔다. 본 연구는 초분광 영상기술을 이용하여 대표적인 식중독균인 살모넬라균의 분광특성을 조사하기 위하여 수행되었다. 연구에는 400~1000 nm 측정 파장대역을 지니는 초분광 영상시스템이 사용되었으며, 식품시료에서 살모넬라균 오염부위를 구분할 수 있는 특성 파장을 조사 및 선정하였다.

Salmonella는 전세계적으로 식중독을 유발하는 주요 원 인 균으로서, 식중독을 유발하는 Salmonella를 신속하게 검출하는 방법은 식품 안전을 위한 중요한 도구이다. Realtime PCR은 식중독균을 검출하기 위한 신속검사법으로 널 리 사용되어 왔다. 최근에는 NBS LabChip real-time PCR 이라는 새로운 시스템이 칩타입으로 조작이 간편하며 초 고속의 real-time PCR 시스템이라는 보고가 있었다. 본 연 구에서는 살모넬라의 신속한 검출을 위하여 NBS LabChip real-time PCR에 기반하여 real-time PCR 반응 시간이 20 분 이내인 검출법을 확인하고자 하였다. 프라이머와 프로 브 설계를 위해 두 개의 타겟 유전자(invA, stn)가 선택되 었으며, 특이도와 민감도(검출한계)를 평가함으로 개발된 검출법을 검증하고자 하였다. 본 연구에서는 특이도 검증을 위해 Salmonella 균주 42주와 Non-Salmonella 균주 21 주를 포함하였으며, 본 방법으로 Salmonella 42주에 대해 서만 정확하게 검출이 가능하였다. 검출한계는 살모넬라 genome DNA 기준으로 101 copies/μL 였으며, 소시지에서 는 4시간 증균 이후 접종균수로서 101CFU/g 에서 102 CFU/ g까지 검출이 가능하였다. 본 연구에서 개발된 검출법은 신속한 식중독 원인조사에 활용될 수 있을 것으로 기대된다.

담배거세미나방과 파밤나방의 유충이 식중독 세균의 일종인 살모넬라균(Salmonella enterica subsp. enterica)에 오염된 먹이를 섭취하였을 때, 살모넬라균을 매개할 수 있는 능력을 지니게 되는 지 평가해 보았다. 먼저 살모넬라균을 108 CFU/mL 이상의 농도로 펩톤수에 현탁하여 토마토 잎맥에 주입한 다음, 살모넬라균에 오염된 토마토 잎을 직경 2cm 크기의 원형으로 잘라서 담배거세미나방 (n=40)과 파밤나방 (n=30)의 2~3령 유충 개체별로 24시간 동안 먹이로 제공하였다. 이후에는 하루에 한 번씩 오염되지 않은 토마토 잎으로 먹이를 교체하면서 개체사육 하였으며, 1일 간격으로 담배거세미나방 (9일간)과 파밤나방 (7일간)의 분변을 채취하여 살모넬라균의 농도변화를 조사하였다. 10개체를 한 반복으로 하여 분변을 분석한 결과, 처음 3일간은 담배거세미나방과 파밤나방 모두 104~108 CFU•총분변량-1•개체-1•일-1에 해당하는 살모넬라균을 분변을 통하여 배출하는 것으로 조사되었다. 이후에 다소 감소하는 경향을 보였지만 살모넬라균이 실험기간 동안 지속적으로 검출되었다. 실험종료 후에 담배거세미나방 노숙유충을 분쇄하여 분석한 결과, 낮은 농도(평균 100.7CFU•개체-1)로 살모넬라균이 검출되었다.

Salmonellosis is a major bacterial zoonosis that causes self-limited enteritis to fatal infection in animals and food-borne infection and typhoid fever in humans. Multidrug-resistant strains of Salmonella spp. has increased over the last several decades and recently causes more serious problems in public health. The present study was investigated bacteriocidal effects of sodium chlorate, sodium azide, sodium cyanide, and sodium salts mixture containing sodium chlorate, sodium azide, and sodium cyanide on infection with S. typhimurium in macrophage RAW 264.7 cells, and antibacterial effects of sodium salts mixture for murine salmonellosis. In infection assay of S. typhimurium in RAW 264.7 cells, bacterial survival rates within macrophage in all treated groups was significantly reduced comparing to that of the control group with the passage of incubation time. Administration of sodium salts mixture showed a therapeutic effect for S. typhimurium infected ICR mice. The mortality of mice treated with sodium salts mixture was 70% until 12 days, while that of control mice was 100% until 9 days after S. typhimurium infection. The results of this study strongly indicate that sodium salts mixture has a potency treatment for murine salmonellosis.

Salmonellosis is the commonest zoonosis worldwide that generally causes enterocolitis and foodborne poisoning which represents a considerable public health burden. Salmonella spp. are potential enteric pathogens and intracellularly replicates in host cells resulting in chronic infections. The medical treatments for salmonellosis have been difficult yet and had a serious problem including the increasing emergence of antibiotic resistance. The present report was designated to investigate the antibacterial effects of Saururus chinensis Baill ethanol extract (SCEE) on pure culture and infection with Salmonella enterica serovar Typhimurium (S. typhimurium) in murine derived macrophage RAW 264.7 cells. In determination of antibacterial activity of SCEE against S. typhimurium, bacterial viability was markedly decreased compared to the control. Also, SCEE significantly induced morphological change (p<0.05) of RAW 264.7 cells. In infection assay of S. typhimurium in RAW 264.7 cells pretreated with 100㎍/㎖ of SCEE, which is a non-cytotoxic concentration, bacterial uptake ability of macrophage was increased corresponding with morphological change, whereas bacterial survival rates within macrophage were markedly reduced compared with untreated control. Furthermore, nitric oxide (NO) production in SCEE-treated cells was slightly increased until 2 h but showed a tendency of decrease after 4 h until 24 h post infection compared with untreated control with S. typhimurium infection. Taken together, these findings demonstrated that SCEE has the antibacterial activity for S. typhimurium and the protective effects against S. typhimurium infection through activating murine macrophage independent on NO, suggesting that SCEE may be beneficial on the disease caused by intracellularly replicating pathogens as a safe alternatives of conventional chemotherapies.

Biological organisms require iron for optimal metabolism. Intracellular pathogens also must secure iron especially during infection of animal hosts expressing NRAMP(natural resistance-associated macrophage protein), a transporter protein sequestering metal ions from pathogens. This study shows that extracytoplasmic function sigma factor σE is required for Salmonella virulence in NRAMP1-expressing mice, and further shows that iron deprivation turns on σE expression of Salmonella. The virulence of σE -deficient Salmonella is completely attenuated in C3H/HeN mice while wild type Salmonella kills all mice. Addition of an iron-chelator DTPA(Diethylene triamine pentaacetic acid) to culture media induces σE expression of Salmonella, but iron supplementation abrogates this induction. These findings suggest that iron limitation in host macrophages can trigger σE -dependent virulence system of Salmonella that may include bacterial iron homeostasis.

Intracellular pathogens must maintain redox homeostasis against the antimicrobial actions of reactive oxygen and nitrogen species produced by host cells. This study proves that glutathione is required to promote survival of an enteric pathogen Salmonella under the conditions producing reactive oxygen or nitrogen species. Glutathione is the non-protein thiol compound distributed in a variety of organisms and possesses strong electron-donating capability to reduce intracellular redox environment. To examine the role of glutathione on Salmonella redox homeostasis under oxidative and nitrosative stress conditions, gshB gene encoding glutathione synthetase was mutated by the one-step PCR inactivation method. The growth of gshB mutant Salmonella producing virtually no glutathione was greatly impaired in the culture media containing either hydrogen peroxide or nitric oxide donors. The results suggest that physiological levels of glutathione can provide a fundamental capability to maintain redox homeostasis for Salmonella in surviving oxidizing conditions of host cells.

In order to investigate the classification and antibiotic resistance of Salmonella species 718 isolates were isolated from patient in Seoul from 1996 to 2001. The two hundred and ninety eight isolates (41.5%) were identified as Sal. Enteritidis, followed by Sal. Typhi 218 isolates (30.4%), and Sal. Typhimurium 87 isolates (12.1%). The identified Salmonella species were most resistant to tetracycline (32.7%), followed by streptomycin (28.0%), ticarcillin (18.1%) and ampicillin (12.4%). Among isolates, 34.7% of Sal. Enteritidis were resistant to tetracycline, 32.3% to streptomycin, 23.2% to ticarcillin, 13.5% to ampicillin, respectively. 13.8% of Sal. Typhi were resistant to streptomycin, 10.6% to tetracycline, respectively. 66.7% of Sal. Typhimurium were resistant to tetracycline, 42.5% to streptomycin, 28.7% to ticarcillin, 26.4% to ampicillin and 17.2% to chloramphenicol, respectively. Of 718 isolates, 324 isolates (45.1%) were resistant to 1 or more drugs and 64 isolates (19.8%) were resistant to 1 drug, 132 isolates (40.7%) were resistant to 2 drugs, 50 isolates (15.4%) were resistant to 3 drugs, 27 isolates (8.3%) to 4 drugs, 27 isolates (8.3%) to 5 drugs, 22 isolates (6.8%) to 6 drugs. The most prevalent multiple resistant pattern was tetracycline-kanamycin (35.5%), followed by tetracycline-kanamycin-ticarcillin (8.3%), and tetracycline-kanamycin-ticarcillin-ampicillin (7.4%). Antibiotic resistant rate of Sal. Typhimurium was 73.6%, followed by Sal. Enteritidis 53.7% and Sal. Typhi 19.3%. Most Sal. Enteritidis was resistant to 1 drug or 2 drugs, whereas Sal. Typhi and Sal. Typhimurium were more resistant to 5 (16.7%) or 6 drugs (26.6%). The old generation antibiotics such as ampicillin, tetracycline, and streptomycin were annually more resistant than the new generation antibiotics such as ceftriaxone, ciprofloxacin or cefoxitin.

This study was carried out to isolate and identify Salmonella species from poultry slaughterhouses and pork meat processing plants during the period from January 1997 to August 1998, and analyze resistance of antimicrobial agents and plasmid profiles of isolated Salmonella strains. A total of 15 Salmonella strains was isolated from poultry carcasses, swine carcasses, pork meats and cutting boards. Identified Salmonella strains were S. typhimurium, S. heidelberg, S. hilingdon, S. mbandaka, and S. virginia. Ten (66.7%) of 15 Salmonella strains showed resistance to antimicrobial agents and five strains (33.3%) of them were resistant to two or more antimicrobial agents. Plasmids were isolated from three Salmonella isolates which had two or more plasmids.

This study was performed to investigate the changes of amount of S. typhimurium during cooking processes using pork and japchae (a Korean food which is made from meat, vegetables and noodles), and to support a practical application to develop a hazard analysis critical control point (HACCP) model. The pork was purchased in a retail shop, cut (0.5 cm × 10 cm × 10 cm, 25 g), tested for Salmonella contamination (results : negative), inoculated with S. typhimurium (10^7 CFU/g), then treated in various conditions related to cooking. After thawing for 24 hours in various conditions, the number of S. typhimurium was increased to 10^(10) CFU/g at a refrigerated temperature (4-10℃), and to 10^(21) CFU/g at room temperature (22-29℃). After thawing in a microwave oven for 40 seconds, the number of S. typhimurium increased to l0^8 CFU/g. During the thawing period, the number of S. typhimurium increased over time. At the refrigerated temperature, the number of the bacteria was 10^(10) CFU/g after 24 hours, 10^(13) CFU/g after 48 hours, and 10^(20) CFU/g after 72 hours. At room temperature the number of bacteria reached 10^(11) CFU/g in 2 hours, 10^(15) CFU/g in 4 hours, 10^(16) CFU/g in 8 hours, 10^(18) CFU/ g in 12 hours, and 10^(21) CFU/g in 24 hours. After cooking in a frying pan (150±7℃) for 3 minutes, the bacterial count was 10^6 CFU/g. After cooking in hot water for 20 minutes, the bacterial count was 10^7 CFU/g at 60℃, 10^6 CFU/g at 63℃, and 10⁴ CFU/g at 65℃. The fried pork was mi×ed with cooked vegetables, noodles, sesame oil, sesame seeds, and seasonings to make Korean japchae. This process took 10±2 minutes. The bacterial count in the japchae increased to 10^7 CFU/g from the count of 10^6 CFU/g of the fried pork before it was mixed with the other ingredients. These results indicate that the amount of S. typhimurium is effected by various different cooking processes. This study can suggest that pork should be cooked in water at over 65℃ for 20 minutes in order to prevent food poisoning, if the pork is contaminated with S. typhimurium. The presence of S. typhimurium in the raw pork is identified in an HA for japchae, and the primary CCP for japchae is inadequate cooking (cooking method and time/temperature). We need to standardize time-temperature-size and amount of pork in cooking japchae, because pork is usually cooked in ordinary frying pans when we make this food.

loom 1993 to 1996, 1,500 cases of foodborne disease was reported annually in Korea. Salmonellosis were 55.1% of the reported bacterial fordborne disease cases. However, in general, it is estimated that the reported incidence of salmonellosis represents less than the real incidence. This study showed that salmonellosis estimates 177,000 cases (about 150 times of reported cases) costing 5.9 billion won in Korea. Only medical costs and productivity losses were included in the estimate of costs of the 177,000 cases estimated to occur in 1996. This estimates were considerably difference to U.S.A. in cases and costs, but not significantly difference in cases/population (%), expense/GDP (%). Understanding the social economic costs of foodborne disease will be endorsed risk assessment as a necessary method for evaluation and improving food safety regulatory programs in Korea.