• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.173-181
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• 1998

Esherichia coli O157 : H7의 slt I, slt II, uid A 및 eaeA 4종 유전자를 동시에 검출하기 위한 multiplex PCR 기법을 확립하고 쇠고기중 직접 E coli O157 : H7 검출시험을 실시하였다. 4 set의 primers를 이용한 multiplex PCR 기법으로 31종의 장내세균에 대한 특이성을 조사한 결과 E coli O157 : H7 에서 1,087bp (eae A), 584bp (slt II), 348bp (slt I) 또는 252bp (uid A)크기의 DNA를 동시에 특이적으로 검출할 수 있었다. E coli O157 : H7 15주는 모두 uid A 및 eae A 유전자가 동시에 검출되었고, 다른 장내세균에서는 검출되지 않았다. slt I 또는 slt II 유전자를 가지고 있는 E coli 표준균주 24종을 이용하여 multiplex PCR 기법과 Vero cell cytotoxicity assay을 비교검사한 결과 베로톡신 산생능과 PCR법의 결과는 일치하였다. mutiplex PCR 기법의 쇠고기중 검출한계는 modified EC(mEC)에서 증균없이는 E coli O157 : H7균 $10^4cells/g$ 이상에서 검출이 가능하였으나 mEC에 1차 증균후 modified TSB 증균하였을 경우에는 10cells/g이하까지도 검출이 가능하였다. 개발된 multiplex PCR 기법을 쇠고기 40종에 직접 적용한 결과 E coli O157 : H7은 검출되지 않았으나 slt I 및 slt II유전자를 가지고 있는 E coli 4종이 검출되었으며, 이들의 혈청형은 O6, O112, O115 및 O139 였다. 이 연구에서 개발된 multiplex PCR은 쇠고기중 E coli O157 : H7을 신속하고 특이적으로 검출하는데 사용할 수 있을 것으로 사료된다.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1181-1184
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• 2011

Total aerobic bacteria, Esherichia coli O157:H7, and Salmonella spp. were examined in commercial liquid pig manures. Commercial liquid pig manures (n=33) were collected from muck joint resource recovery plant at April, June, August, October 2009, Korea. Total aerobic bacteria were incubated at $37^{\circ}C$ for 24-48 hrs, and quantified as a colony-forming unit (CFU) $mL^{-1}$. Analysis of Esherichia coli O157:H7 and Salmonella spp. were followed by Korean Food Standards Codex method. Colony of Salmonella spp. was confirmed by API kit and real time polymerase chain reaction (PCR). Total aerobic bacteria isolated from fermented commercial liquid pig manures ranged from 2.8 to $24.3{\times}10^4\;CFU\;mL^{-1}$. Esherichia coli O157:H7 was not detected, and Salmonella spp. showed the low detection frequency at only 1 sample. This study suggests that continuous monitoring in commercial liquid pig manures is required to improve the agricultural food through management of agricultural land contaminated with liquid pig manures.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.819-822
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• 2021

To enhance phage endolysin-mediated cell wall disruption of Escherichia coli O157:H7, the cells were co-treated with aromatic compounds, namely thymol or eugenol, found in essential oils and endolysin LysECP26. Interestingly, the minimal inhibitory concentrations of LysECP26 was four times lower when used in combination with either of the two compounds than when it was used alone. This synergistic activity was also confirmed by viable cell counting. Within 1 h of LysECP26 and eugenol or thymol co-treatment to the cells, there was a 2.3 or 3.8 log CFU/mL reductions, respectively. Additionally, field emission scanning electron microscopy showed cell wall disruption and severe morphological alterations of the cells in case of the combination treatments. Therefore, endolysin and thymol or eugenol co-treatment can help in developing efficient bio-control strategies against gram-negative pathogen E. coli O157:H7.

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.168-173
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• 2013

This study was carried out to develop and validate predictive models of E. coli O157:H7 growth. Growth data of E. coli O157:H7 in Paprika were collected at 12, 24, 30 and $36^{\circ}C$. The population increased into 3.0 to 3.8 log10 CFU/g within 4 days, then continued to increase at a slower rate through 10 days of storage at $12^{\circ}C$. The lag time (LT) and maximum specific growth rate (SGR) obtained from each primary model was then modeled as a function of temperature using Davey and square root equations, respectively. For interpolation of performance evaluation, growth data for a mixture of E. coli O157:H7 were collected at time intervals in paprika incubated at the different temperatures, which was not used in model development. Results of model performance for interpolation data demonstrated that induced secondary models showed acceptable goodness of fit. Relative errors in the LT and SGR model for interpolation data (18 and $27^{\circ}C$) was 100%, which show acceptable goodness of fit and validated for interpolation. The primary and secondary models developed in this study can be used to establish tertiary models to quantify the effects of temperature on the growth of E. coli O157:H7 in paprika.

• Clinical and Experimental Pediatrics
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• v.46 no.2
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• pp.143-153
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• 2003

Purpose : Infection with Shiga-like toxin (SLT)-producing Escherichia coli, an emerging human pathogen found particularly in young children under 5 years of age, causes a spectrum of illnesses with high morbidity and mortality, ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome. Host mediators play an important role in the pathogenesis of SLT-I toxicity. The experiments described here were designed to investigate the effect of SLT-I on TNF-${\alpha}$ production and to understand the effect of TNF-${\alpha}$ on GB3 expression. We also further examine the relationship between the Gb3 level and the differential susceptibility of cells to the cytotoxic action of SLT-I. Methods : The effect of purified SLT-1 from E. coli O157 : H7 (ATCC 43890) on tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) production in Raw264.7 cells was investigated. Many mediators regulate endothelial cell membrane expression of the glycolipid globotriaosyleramide (Gb3), which serves as the toxin receptor, suggesting that the host response to the toxin or other bacterial products may contribute to pathogenesis by regulating target cell sensitivity to the toxins. Therefore, the relationships between Gb3 expression and cytotoxicity against SLT-I on three types of cells were evaluated. Results : Detectable levels of TNF-${\alpha}$ were produced as early as six hours after induction and continued to increase during 48 hours by SLT-I. It was also found that Vero cells and dendritic cells (DC2.4 cells) expressed high levels of Gb3, 83% and 68%, respectively, and that Raw264.7 cells had a low level of Gb3 (29%) and appeared refractory to cytotoxicity against SLT-I. Vero cells and DC2.4 cells expressing high levels of Gb3 were highly susceptible to SLT-I. Furthermore, macrophages showed a resistance to SLT-I cytotoxicity, despite the fact that Gb3 expression was enhanced. Conclusion : These results strongly suggest that the expression of Gb3 is necessary but not sufficient to confer sensitivity of macrophages to SLT-I and further underpin the important role of SLT-I and its Gb3 receptors in the pathogenesis of E. coli O157 infection.

• Journal of Life Science
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• v.17 no.4 s.84
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• pp.482-492
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• 2007

Infection with Shiga-like toxin (SLT)-producing Escherichia coli causes a spectrum of illnesses with high morbidity and mortality. Host mediators play an important role in the pathogenesis of SLT-I toxicity. We here investigated the effect of SLT-I on tumor necrosis $factor-{\alpha}\;(TNF-{\alpha})$ production, effect of $TNF-{\alpha}$ on glycolipid globotriaosyleramide (Gb3) expression, and relationship between Gb3 level and differential susceptibility of cells to SLT-I. In this study, we observed that detectable levels of $TNF-{\alpha}$ are produced 6 hrs after induction and continued to increase during 48 hrs by SLT-I. It was also found that Vero cells and dendritic cells expressed high levels of Gb3, 83% and 68%, respectively, and that macrophages had a low level of Gb3 (29%) and showed refractory to cytotoxicity against SLT-I. Vero cells and dendritic cells expressing high levels of Gb3 were highly susceptible to SLT-I. furthermore, macrophages showed a resistance to SLT-I cytotoxicity, despite the fact that Gb3 expression was enhanced. These results suggest that the expression of Gb3 is necessary, but not sufficient to confer sensitivity of macrophages to SLT-I and further underpin the important role of SLT-I and its receptor, Gb3, in the pathogenesis of E. coli O157 infection.