본 연구는 광주광역시에 유통·판매되고 있는 가금육을 대상으로 식중독 발생 가능성 높은 캠필로박터균의 검출 여부와 분리된 균주의 항생제 내성 및 유전적 특성을 조 사하였다. 전체 307건의 가금육(닭 223건, 오리84건) 중 111건에서 캠필로박터균이 검출(36.2%)되었고 116균주 (Campylobacter jejuni 102균주, Campylobacter coli 14균 주)를 분리하였다. 가금류별 캠필로박터균 검출률은 닭고 기 26.0%, 오리고기 63.1% 이었고, 5건(닭 1건, 오리 4 건)의 시료에서 Campylobacter jejuni, Campylobacter coli 가 동시에 검출되었다. 분리된 균주의 항생제 내성 시험 결과 99균주(85.3%)는 1가지 이상의 항생제에 대하여 내 성을 보였다. 그 중 ciprofloxacin, nalidixic acid에 내성 을 보이는 균주가 각각 98균주(84.5%), 96균주(82.8%)로 가장 많았고, 그 외에 tetracycline (44.0%), gentamicin (2.6%)에 내성을 나타냈다. 분리된 균주의 혈청형 확인 결과, HS2형 20균주, HS15형 11균주, HS19형 9균주, HS8 형 8균주 등이 확인 되었고, HS42형, HS6형, HS53형, HS4A형, HS5형, HS18형, HS12형, HS27형 그리고 HS37 형이 확인 되었다. 따라서 조리 가공 시 교차오염이 발 생하지 않도록 조리기구 등에 대한 위생적 관리와 충분 한 가열 조리 등의 식중독 예방을 위한 주의가 필요할 것으로 생각된다.

Rapid and accurate detection of pathogenic bacteria is crucial for various applications, including public health and food safety. However, existing bacteria detection techniques have several drawbacks as they are inconvenient and require time-consuming procedures and complex machinery. Recently, the precision and versatility of CRISPR/Cas system has been leveraged to design biosensors that offer a more efficient and accurate approach to bacterial detection compared to the existing techniques. Significant research has been focused on developing biosensors based on the CRISPR/Cas system which has shown promise in efficiently detecting pathogenic bacteria or virus. In this review, we present a biosensor based on the CRISPR/Cas system that has been specifically developed to overcome these limitations and detect different pathogenic bacteria effectively including Vibrio parahaemolyticus, Salmonella, E. coli O157:H7, and Listeria monocytogenes. This biosensor takes advantage of the CRISPR/Cas system's precision and versatility for more efficiently accurately detecting bacteria compared to the previous techniques. The biosensor has potential to enhance public health and ensure food safety as the biosensor’s design can revolutionize method of detecting pathogenic bacteria. It provides a rapid and reliable method for identifying harmful bacteria and it can aid in early intervention and preventive measures, mitigating the risk of bacterial outbreaks and their associated consequences. Further research and development in this area will lead to development of even more advanced biosensors capable of detecting an even broader range of bacterial pathogens, thereby significantly benefiting various industries and helping in safeguard human health

Bis(2-ethylhexyl) phthalate (DEHP) is one of the plasticizers used in the polyvinyl chloride (PVC) industry. It is known to be easily released into the environment. In this study, we investigated effects of DEHP on growth, metabolic pathway, and virulence gene expression in soil-borne bacterial plant pathogen, Pectobacterium carotovorum SCC1 using in vitro assays. As a result, DEHP at 20 μg mL-1 did not affect the growth, cell membrane permeability, or ATPase activity of P. carotovorum SCC1. However, it decreased succinyl-CoA synthase (SCS) activity in the tricarboxylic acid (TCA) cycle. Relative expression levels of virulence genes encoding pectate lyase and pectin were differentially influenced by DEHP treatment. These results suggest that biological characteristics of P. carotovorum might be influenced by DEHP in soil.

The epidemiological associations between poultry farm biosecurity measures and the 2016/18 highly pathogenic avian influenza (HPAI) epidemics were evaluated using a multivariate logistic model. In the model, 11 biosecurity measures were used as independent variables in the model: a security fence to keep wild birds out of the farm, a security gate on the farm, a farm signboard, number of footbaths for disinfecting footwear, number of anterooms, U-shaped disinfection farm gate, a tunnel-shaped disinfection farm gate, a high-pressure disinfectant fogging farm gate, disinfectant booth for farm workers and visitors, high-pressure disinfectant sprayer in the farm, and personnel disinfectant sprayer in the farm. Two hundred and eighty-eight poultry farms (144 HPAI-confirmed and 144 non-confirmed) were used as the dependent variable. The numbers of footbaths and anterooms were converted to a categorical measurement format using a general additive model. The likelihood of an HPAI outbreak in a poultry farm with a fence to prevent contact between wild birds and domestic fowl was less than that of farms without a fence (OR: 0.54, P value: 0.01). The Akaike information criterion score of the multivariate model (370.91) was less than that of the univariate logistic model for each biosecurity measure. From an HPAI control perspective, it is recommended for poultry farmers to construct a wild bird-proof fence to decrease the HPAI outbreak risk.

The mallard and spot-billed duck are representative migratory bird species wintering in the Republic of Korea. They can be a highly pathogenic avian influenza (HPAI) virus carrier during their wintering movement. From September 2014 to June 2015, 162 poultry farms were confirmed to have a HPAI infection. The current study estimated the home range of the mallard and spot-billed duck during the 2014/15 HPAI epidemics to explore the relationship between the wintering site of the migratory birds and the geographical locations of HPAI-infected farms. A Brownian bridge movement model was applied to estimate the home ranges of 13 mallards and three spot-billed ducks. As a result, 22 HPAI-infected poultry farms were located geographically in the 99% cumulative probability contour of the home range of the mallard, but no HPAI-infected poultry farm was found in spot-billed duck’s home range. In the case of one spot-billed duck, however, it has two wintering sites: Chungcheongnam-do and Jeollanam-do. Considering that migratory birds can be a major driven factor in HPAI virus transmission from wild birds to poultry farms, it is recommended for poultry farms located within the home range of migratory birds to increase their biosecurity level during wintering season of migratory birds.

본 연구는 광주광역시에 유통·판매되고 있는 소고기를 대상으로 식중독 발생 비율이 높은 병원성대장균의 검출 여부와 분리된 균주의 항생제 내성 및 유전적 특성을 조사 하였다. 전체 335건의 소고기 중 82건에서 병원성대장균이 검출(24.4%)되었고 102개의 다양한 균주를 분리하였다. 분리균주의 병원성 유전자를 토대로 분류한 결과, EHEC가 66 균주로 가장 많았고 EHEC와 EPEC 등 2가지 유전자가 동시에 검출된 균주도 11균주가 있었다. 분리된 균주의 항생제 내성 시험결과, 30균주는 1가지 이상의 항생제에 대하여 내성을 보였다. 그 중 tetracycline에 내성을 보이는 균주가 27균주로 가장 많았고 그 외에 ampicillin, trimethoprim/ sulfamethoxazole, chloramphenicol 등의 순으로 많았다. 분리 된 균주의 혈청형 검사 결과, 혈청형은 O26, O91, O103, O104, ,O111, O113, O121, O128 및 O145로 확인되었다. 따라서 소고기의 조리 가공 시 교차오염이 발생하지 않도록 조리기구 등에 대한 위생적 관리와 충분한 조리 등의 식중독 예방을 위한 주의가 필요할 것으로 생각된다.

The current study explored the epidemiological associations between the 2016/18 highly pathogenic avian influenza (HPAI) epidemics and spatial factors, including the distance from a poultry farm to the closest groundwater source, migratory bird habitat, eco-natural area, and poultry farm altitude. We included 14 spatial factors as independent variables. The variables were used in the original continuous measurement format. In total, 288 poultry farms (144 HPAI-confirmed and 144 non-confirmed) were used as the dependent variable. In addition, the variables’ continuous measurement was converted to a categorical measurement format by using a general additive model. For risk factor analysis based on the continuous measurements of spatial factors, the non-graded eco-natural area distance (odds ratio [OR]: 1.00) and the grade one eco-natural area distance (OR: 0.99) were statistically significant independent variables. However, in the risk factor analysis based on the categorical measurement format of the spatial factors, the non-graded eco-natural area distance (OR: 0.08) and poultry farm altitude (OR: 0.44) were statistically significant independent variables in both a univariate and multiple logistic regression model. In other words, when a poultry farm was located far from the non-graded eco-natural area or in a highland area, the likelihood of an HPAI epidemic would decrease. From an HPAI control perspective, it is recommended that the government apply increased levels of biosecurity measures, such as bird-nets, fences, intensive disinfection of equipment, and regular bird health monitoring, for poultry farms located near non-graded eco-natural areas or in a lowland area.

Since the first HPAI epidemics in 2003, there has been little epidemiological research on the association between HPAI epidemics and vehicle movements around poultry farms. This study examined the relationship between vehicle movements around poultry farms and the 2014/15 HPAI epidemics in the Republic of Korea using two methods: a boosted regression trees (BRT) model and logistic regression of a generalized linear model (GLM). The BRT model considers the non-linearity association between the frequency of vehicle movements around poultry farms and the HPAI outbreak status per province using a machine learning technique. In contrast, a GLM assesses the relationship based on the traditional frequentist method. Among the three types of vehicle movements (outbound, inbound, and within), only the outbound was found to be a risk factor of the 2014/15 HPAI epidemics according to both the BRT model and multivariate logistic regression of GLM. In the BRT model results, the median relative contribution of the log-transformed outbound variable was 53.68 (range: 39.99 – 67.58) in the 2014 epidemics and 49.79 (range: 33.90 – 56.38) in the 2015 epidemics. In the GLM results, the odds ratio of the log-transformed outbound variable was 1.22 for the 2014 HPAI epidemics (p < 0.001) and 2.48 for the 2015 HPAI epidemics (p < 0.001), respectively. The results indicated that intensive disinfection measures on outbound movement were needed to reduce the risk of HPAI spread. The current BRT models are suitable for risk analysis because the median area under the receiver operating characteristic curve was 0.83 (range: 0.74 – 0.91) and 0.85 (range: 0.73 – 0.87) for the 2014 and 2015 epidemics models, respectively. The Akaike information criterion scores for the multivariate logistic regression of GLM were 150.27 and 78.21 for the 2014 and 2015 epidemics models, respectively. These scores were relatively lower than those from the univariate logistic regression of GLM.

Whey is a major by-product of cheese manufacture and contains many valuable constituents, such as β-lactoglobulin, lactoferrin and immunoglobulin. The current study determined the anti-biofilm activity of bioconversion of whey by Lactobacillus plantarum (LP-W), L. rhamnosus GG (LR-W), L. brevis (LB-W) and Enterococcus faecium (EF-W) against foodborne pathogenic bacteria, Escherichia coli O157:H7 and Listeria monocytogenes. When the foodborne pathogenic bacteria were co-incubated with LP-W, LR-W, LB-W or EF-W, biofilms by E. coli O157:H7 and L. monocytogenes were significantly reduced by all bioconversion of whey. Moreover, LP-W, LR-W, LB-W and EF-W also dramatically reduced pre-formed biofilm by E. coli O157:H7 and L. monocytogenes, suggesting that the bioconversion of whey effectively suppress the development and disruption of biofilm by foodborne pathogenic bacteria. Furthermore, in order to determine the growth kinetics of E. coli O157 and L. monocytogenes planktonic cells in the presence the bioconversion of whey, LP-W, LR-W, LB-W and EF-W did not significantly inhibited the growth of foodborne pathogenic bacteria, implying that the bioconversion of whey reduces the biofilm without the decrease of bacterial growth. Taken together, these results suggest that bioconversion of whey by lactic acid bacteria could be a promising agent for the reduction of microbial biofilm.

Avian pathogenic Escherichia coli (APEC) is an agent associated with colibacillosis and an important primary pathogen with responsible for significant economic losses in chickens. This study investigated the molecular characteristics including virulence and antimicrobial resistance of serotype O78 APEC isolates, the predominant serotype, in Korea. Among 16 O78 APEC isolates, 13 isolates carried the genes conferring resistance to ß-lactam (blaTEM), aminoglycoside [aac(3)-II], plasmid-mediated quinolone (qnrA), tetracycline (tetA and tetB), sulfonamide (sul1 and sul2), or chloramphenicol (catA1). Three isolates showed resistance to gentamicin and carried aminoglycoside-modifying enzyme gene, aac(3)-II, simultaneously. Ten O78 APEC isolates showed resistance to nalidixic acid, but only qnrA gene among plasmid-mediated quinolone resistance genes was detected in one isolate. The tetA and tetB genes were also detected in nine and two isolates, respectively. In distribution of phylogenetic groups, four O78 APEC isolates only belonged to group D. But all isolates carried three to five essential virulence genes regardless of phylogenetic groups. Virulence factors and antimicrobial resistance of the most predominant serotype, O78, in chickens tested in this study can be significant role in persistence of APEC in Korea.

본 연구에서는 V. vulnificus와 V. cholerae를 중심으로 국내에서 유통되는 우렁쉥이에 대한 위해평가를 실시하였다. 위험성 확인 단계에서 병원성 비브리오균의 위험성에 대해 조사하였고, 노출평가 단계에서는 초기오염도를 산출 하기 위하여 네 권역에서 우렁쉥이의 병원성 비브리오균 오염실태를 조사하였다. 또한 대형할인마트, 시장 및 횟집 에서 관리자와의 면담을 통하여 유통 시간을 조사하였으며, 시료의 품온 및 진열대 온도를 직접 측정하여 유통 온도를 수집하였다. 예측모델 개발을 위하여 병원성 비브리오 균을 혼합하여 우렁쉥이에 접종 후 다양한 온도(7oC, 10oC, 15oC, 20oC)에 저장하면서 시간대별로 꺼내어 세균 의 생장 및 사멸을 확인하였다. 섭취자 비율 및 섭취량은 2016년 국민건강영양조사 원시자료를 활용하여 산출하였으며 용량-반응모델 선정을 위하여 문헌조사를 실시하였고, 최종적으로 수집된 데이터들을 활용하여 시나리오를 구성하였다. 오염실태 조사 결과 V. vulnificus는 검출되지 않았으며 V. cholerae는 101개의 시료 중 1개에서 양성으로 검출되었다. 유통환경조사 결과 우렁쉥이는 최소 1시간, 최대 48시간까지 진열되는 것으로 조사되었고 0-10oC 로 유통되는 것을 확인하였다. 예측모델 개발 결과 모든 온도(7oC, 10oC, 15oC, 20oC)에서 병원성 비브리오균은 점차 사멸하는 경향을 띄었으며 개발된 모델의 적합성 검증 결과 RMSE값이 0에 가까워 개발된 모델이 우렁쉥이에서 병원성 비브리오 균의 균주 변화를 묘사하기에 적합하다 고 판단되었다. 섭취자 비율 및 섭취량은 0.26% 및 65.13 g 으로 나타났으며 용량-반응 모델은 Beta-Poisson 모델을 사용하였다. 최종적으로 @RISK Fitting 프로그램을 활용하여 위해도를 추정한 결과, 우렁쉥이를 섭취하였을 경우 1일 1인에게서의 V. vulnificus로 인한 식중독 발생 확률은 평균 2.66×10-15, V. cholerae로 인한 식중독 발생 확률은 평균 1.02×10-12으로 추정되었다. 또한 민감도 분석결과 섭취자 비율이 위해도에 가장 큰 양의 상관관계를 나타내는 것으로 조사되었다. 해당 연구결과는 국내 우렁쉥이 유통 과정에서 병원성 비브리오균에 대한 안전한 수산물을 생산하는데에 기여할 수 있을 것으로 판단된다. 또한 위해 평가 결과는 국내 수산물에서 V. vulnificus와 V. cholerae 에 대한 기준·규격을 설정하는데 기초자료로 활용할 수 있을 것으로 사료된다.

The goal of the current study was to estimate the contribution of poultry farm vehicle movement frequency to the 2014 highly pathogenic avian influenza (HPAI) epidemic using both global and local regression models. On one hand, the global model did not consider the hypothesis that a relationship between predictors and the outcome variable might vary across the country (spatially homogeneous), while on the other hand, the local model considered that there was spatial heterogeneity within the country. The HPAI outbreak status in each province was used as a dependent variable and the number of poultry farm vehicle movements within each province (within variable), the number of poultry farm vehicle movement from one province to another province (outbound variable), the number of poultry farm vehicle movements from other provinces to one province (inbound variable), and the number of poultry farms in each province were included in the model as independent variables. The results of a global model were as follows: estimated coefficient of the log-transformed within variable was 0.73, that of the log-transformed outbound variable was 2.04, that of the log-transformed inbound variable was 0.74, and that of the number of poultry farms was 1.08. Only the number of poultry farms was a statistically significant variable (p-value < 0.001). The AIC score of the global model was 1397.5. The results of the local model were as follows: estimated median coefficient of the log-transformed within variable was 0.75, that of the log-transformed outbound variable was 2.54, that of the log-transformed inbound variable was 0.60, and that of the number of poultry farms was 0.07. The local model’s AIC score was 1382.2. The results of our study indicate that a local model would provide a better understanding of the relationship between HPAI outbreak status and poultry farm vehicle movements than that provided by a global model.

The goal of the current study was to explore the relationship between vehicle movement frequency and a disease outbreak by using the example of the highly pathogenic avian influenza (HPAI) outbreak in 2014 in the Republic of Korea. To explore the relationship between the HPAI outbreak status of Korean provinces and vehicle movements, both an ordinary least square model (OLS) and a maximum entropy model (MaxEnt) were built. The HPAI outbreak status of each province was used as a dependent variable. The number of poultry farm vehicle movements within the province (within variable), the number of poultry farm vehicle movements from one province to another province (outbound variable), the number of poultry farm vehicle movements from other provinces to one province (inbound variable), and the number of poultry farms in each province were included in the models as independent variables. Results of the OLS model were as follows: the estimated coefficient of the log-transformed within variable was -0.30, that of the log-transformed outbound variable was 0.71, that of the log-transformed inbound variable was -0.30, and that of the number of poultry farms was 0.07; however, only the number of poultry farms per province was statistically significant. Results of the MaxEnt model were as follows: the median relative contribution of the log-transformed outbound variable was 52.0 (range: 12.2–83.9), that of the log-transformed inbound variable was 34.4 (range: 8.8–83.4), that of the log-transformed within variable was 3.7 (range: 1.8–7.3), and that of the number of poultry farms per province was 0.7 (range: 0.0–11.7). The area under the receiver operating characteristics curve was 0.683. The results of current study should be helpful for planning a national HPAI surveillance program to locate surveillance resources with the consideration of risk level of provinces.