• Journal of Food Hygiene and Safety
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• v.18 no.3
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• pp.118-124
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• 2003

For the rapid detection of various pathogenic microorganisms from food sample, various kinds of kits have been developed and commercially available in the markets. With the advantages of speed, accuracy and easiness, the market of these kits has gradually increased for the QC and QA field of food company as well as testing facilities or laboratories. In this study, the characteristics such as the detection limit and the sensitivity of immunochromatographic type of rapid detection kit (Donga Co, Korea, D-kit) for E. coli 0157:H7 developed by monoclonal antibody were examined and also the possibility of application of the kit to food samples was evaluated. The reference kits used for comparison study were Reveal E. coli 0157:H7 (Neogen Co., USA, R-kit) and VIP EHEC kit (Biocontrol Inc., USA, V-kit) occupying major market share. In the detection limit test with the E. coli 0157:H7 reference, both R-kit and D-kit showed a distinct positive reaction in $10^4$/ml and weak positive reaction in $10^3$/ml, whereas V-kit showed a same reaction in 105/ml. Also, it was identified that the culture treated with heat showed more sensitivity than no heat treated culture. The sensitivity test was conducted against 22 isolates of E. coli 0157:H7, 7 strains of non-O157:H7 verotoxin-producing E. coli, 40 strains of E. coli with different O and H antigen type, and 38 strains of non-E. coli Enterobacteriaceae, and all of the test strains except three were showed exactly three were showed exactly the same reaction against three kinds of the tested kits. All the three kinds of kits showed a positive reaction against E. coli O157:H19, E. coli O148:H18 and Salmonella galinarium. We suppose that there might be a similarity in serological property between these three strains and O157:H7. From the test results, it can be concluded that there is (was) no difference between the D-kit developed in this study and R-kit or V-kit based on the detection limit and sensitivity.

• Korean journal of food and cookery science
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• v.13 no.2
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• pp.106-112
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• 1997

The effect of low concentrations of allspice (Pimenta dioica L.) in culture broth as an antibacterial agent against Escherichia coli 0157:H7 and Staphylococcus aureus 196E was tested at 35,5 and -20$^{\circ}C$. Tryptic soy broth (TSB) containing 0∼2% (w/v) of allspice was inoculated with 10$\^$5/∼10$\^$6/ cells/$m\ell$ of E. coli and S. aureus and incubated at each temperature. The growth of E. coli was not inhibited at 0.1∼1.0% allspice and growth occured at 2％ allspice but only after a prolonged lag period. Growth of S. aureus was inhibited with increasing concentration of allspice at 35$^{\circ}C$. Growth of S. aureus occured at the presence of 0.1∼0.3% allspice but the viability of S. aureus at 0.5∼2.0% allspice was decreased during storage at 35$^{\circ}C$. During refrigerated storage at 5$^{\circ}C$, inhibition of E. coli and S. aureus was increased with the progress of time and increasing spice concentration. During frozen storage at -20$^{\circ}C$, antibacterial activity of allspice against E. coli was increased with increasing storage time and spice concentration while that activity against S. aureus was effective during early period of storage. There was no major changes in population of S. aureus in TSB with different concentration of spice frozen at -20$^{\circ}C$. Viable counts of E. coli and S. aureus at 0.l％ of allspice was less than that of control during frozen storage.

• Food Science of Animal Resources
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• v.23 no.3
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• pp.278-283
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• 2003

Feasibility tests on using liposomes for detecting food-borne pathogenic bacteria were studied with E. coli 0157:H7 as a model analyte. lmmunoliposomes, whose surface was conjugated with anti-E. coli 0157:H7 IgG and which encapsulated the marker dye, sulforhodamine B, were used for the detection label. Among the feasibility tests, the first test was to use a test-strip on which antibodies to anti-E. coli O157:H7 IgG were immobilized. In this format, immunoliposomes that did not bind to E. coli O157:H7 in sample were captured and then exhibited a visible signal which was inversely related with the number of E. coli O157:H7 in sample. The second test was a direct liposome assay followed by immunomagnetic separation. In this format, immunoliposomes which were bound to E. coli O157:H7 were lysed with detergent and produced a signal which was proportionally related with the number of E. coli O157:H7 in sample. The results from both formats indicate that liposomes can be utilized as a detection label.

• Journal of Food Hygiene and Safety
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• v.13 no.2
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• pp.112-120
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• 1998

This study was performed to investigate the synergistic effect of chitosan and sorbic acid as a new food preservative. So it was performed to investigate inhibitory effect on growh of E. coli 0157:H7, gram negative pathogenic food borne disease bacteria and of S. aureus, gram positive food borne disease bacteria in chitosan, sorbic acid and combination of chitosan and sorbic acid. Minimun Inhibitory Concentration (MIC) of chitosan in E. coli 0157:H7 was 500 ppm at pH 5.0, 250 ppm at pH 5.5, 500 ppm at pH 6.0, and 2000 ppm at pH 6.5, while in Staph. aureus 31.25 ppm at pH 5.0 and 62. 5 ppm at more than pH 5.5. also, MIC of sorbic acid in E. coli 0157:H7 was 500 ppm at pH 5.0, 1500 ppm at pH 5.5, and 2000 ppm at more than pH 6.0, while in Staph. aureus 1500 ppm at pH 5.0 and more than 2000 ppm at more than pH 5.5. Due to the effect of pH in E. coli 0157:H7, MIC of combined chitosan and sorbic acid was 500 ppm of chitosan with 500 ppm of sorbic acid at pH 6.5, but 250 ppm of chitosan with 31.3 ppm of sorbic acid at pH 5.0. In Staph. aureus, there was great effect of chitosan, but neither effect of pH nor sorbic acid. When E. coli 0157:H7 were treated with 500 ppm of chitosan with 500 ppm of sorbic acid and 250 ppm of chitosan with 250 ppm of sorbic acid at pH 6.5, they were inhibited. But, they were increased at the initial concentration of bacteria at 1000 ppm of chitosan in 18 hours, at 500 ppm of chitosan in 36 hours. There was no effect of growth inhibition with sorbic acid but great effect with chitosan on Staph. aureus. The correl~tions between MICs of chitosan and sorbic acid in E. coli 0157:H7 accoding to pH were higher than those in Staph. aureus. R values in E. coli 0157:H7 were 0.95 (p<0.01), 0.99 (p<0.01), 0.97 (p<0.01), and 0.99 (p<0.01) at pH 6.5, 6.0, 5.5, and 5.0 respectively. The synergistic effect of chitosan and sorbic acid in E. coli 0157:H7 could be confirmed from the result of this experiment. Therefore, it was expected that the food preservation would increase or maintain by using sorble acid together with chitosan, natural food additive that did no harm to human body.

• Korean journal of food and cookery science
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• v.14 no.1
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• pp.9-15
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• 1998

The inhibitory effect of clove (Eugenia caryophyllata Thumb) on the growth of Escherichia coli 0157:H7 was determined. Tryptic soy broth (TSB) containing 0∼0.5% (w/v) of clove was inoculated with 10/sup/5∼10/sup/7 CFU/ml of E. coli and incubated at 5 different temperature (35, 5, -20, 50 and $55^{\circ}C$). The growth of E. coli was not inhibited at 0.1% clove and growth occured at 0.3% after a prolonged lag period while viable cells of E. coli decreased at 0.5% clove during storage at $35^{\circ}C$. During 32 days of refrigerated storage at $5^{\circ}C$, survivors of E. coli were decreased with the progress of time and increasing clove concentration. At the presence of 0.3 or 0.4% clove, bacterial cells were dead at the end of refrigerated storage. During frozen storage at -$20^{\circ}C$, survivors of E. coli at the presence of 0∼0.4% clove were decreased 2.9∼4.07 log cycles for 4 days of early period and then decreased 1.0∼2.1 log cycles through the frozen storage. There were small changes in populations of E. coli in TSB between different concentrations of clove during frozen storage. The D-values for E. coli at $50^{\circ}C$ were 105.26, 22.47, 13.76, 11.14 and 10.17 min at clove 0, 0.1, 0.2, 0.3, 0.4%, respectively. The D-values for E. coli at $55^{\circ}C$ were 10.75, 8.95, 7.40, 5.96 and 4.96 min at clove 0, 0.1, 0.2, 0.3, 0.4%, respectively. Antibacterial activity of clove against E. coli was more effective at $50^{\circ}C$ than at $55^{\circ}C$.

• Korean Journal of Veterinary Research
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• v.36 no.3
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• pp.607-614
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• 1996

Several methods for rapid and accurate detection of VTe-producing E coli were established. These methods contain beta-glucuronidase-secretion test, beta-haemolysis-production test in blood agar, verocytotoxicity test, and PCR. All of the VTe-producing strains made beta-haemolysis on 5% sheep blood agar. VTe-producing strains secreted beta-glucuronidase whereas 0157:H7 strains producing VTI or VTII did not secrete that enzyme. Verocytotoxicity test was established for rapid diagnosis. VTe detection was rapider in Vero cell suspension than Vero cell monolayer. In PCR, there was a positive result only in VTe-producing E coli, not in VTI or VTII-producing E coli. In this experiment, 165 strains of E coli were islated from feces or intestinal contents of post-weaning piglets showing nervous sign or diarrhea. And 20 strains of E coli that produced VTe were selected by verocytotoxicity test and PCR. According to these experiments, there was a direct correlation between verocytotoxicity test and PCR. And verocytotoxicity test is recommended as a routine diagnostic method and PCR does as a accurate diagnostic method to detect VTe-producing E coli.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.131-135
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• 2000

The inhibitory effect of various organic acids on the growth and survival of Escherichia coli O157:H7 in tryptic soy broth with 0.6% yeast extract at 37$^{\circ}C$ or 4$^{\circ}C$ was determined. Minimal inhibitory pHs of acetic acid, citric acid, fumaric acid, hydrochloric acid and lactic acid were 5.0, 4.0, 4.5, 4.0 and 4.5, respectively. Acetic acid (0.012 m) showed the strongest antimicrobial activity, based on the pH values or equivalent molar concentrations, followed by lactic acid (0.0006 M), fumaric acid (0.004M) and citirc acid (0.004 M), respectively, E. coli O157:H7 with an initial inoculum of {TEX}$10^{7}${/TEX} CFU/ml and {TEX}$10^{5}{/TEX} CFU/ml in tryptic soy broth supplemented with 0.6% yeast extract, acidified to target pH with citric, fumaric and lactic acids at 37$^{\circ}C$, was completely inactivated after 7 d and 5 d incubation, respectively, except for the acetic acid (9 d). The bactericidal effect decreased at the same pH when the incubation temperature a was reduced from 37$^{\circ}C$ to 4$^{\circ}C$. The pH values of 0.2% acetic (pH 5.1), 0.6% citric (pH 4.2) and 0.4% lactic acid (pH 4.3) in TSBYE were almost correspondent to the minimal inhibitory pH values on E. coli O157:H7 of acetic (pH 4.0), citric (pH 4.0) and lactic acids (pH 4.5).

• Journal of Dairy Science and Biotechnology
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• v.15 no.1
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• pp.11-20
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• 1997

This study was designed to carry out an observation on the growth inhibitory effect of fermented milk by the the lactic acid bacteria such as Lactobacillus bulgaricus, L. acidophilus and L. cormatus against pathogenic Escherichia coli O157:H7 were studied in vitro. The results of this study were as follows : The BL broth culture of L. bulgaricus, L. acidophilus and L. cormatus gave a similar extent of growth inhibitory effects against the pathogenic E. coli O157:H7 were after incubation time within 18 hours. The inhibitory effects of the fermented milk were observed on the survival time of pathogenic E. coli O167:H7 in the various fermented milk at 37${\circ}$C shaking water bath (70 rpm) were after incubation time between 140 and 200 minutes. These results indicated that major portion of growth inhibitory effects of fermented milk with various lactic acid bacteria against pathogenic E. coli O157:H7 was possible due to the acid, and minor portion to the other antibacterial substances.

• 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.

• Korean Journal of Veterinary Research
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• v.46 no.2
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• pp.135-142
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• 2006

Shiga toxin (stx) producing Escherichia coli (STEC) causes various clinical signs in animal and human. In this study, 255 fecal samples from calves showing diarrhea were collected from cattle farms in Chonnam province during the period from January 2005 to July 2005. Twenty six STEC (10%) were isolated from 255 fecal samples by PCR. The isolates displayed three different stx combinations (stx1 [69%], stx1 and stx2 [15%], and stx2 [38%]). The isolates were further studied for virulence associated genes and antimicrobial resistance to define the virulence properties. Intimin (eaeA), enterohemolysin (hlyA), and lipopolysaccharide (rfbE) virulence genes were detected in 6 (23%), 7 (26%), and 1 (3.8%) of the isolates, respectively, by PCR. One isolate possessing rfbE gene was typed as E. coli 0157 : H7 by agglutination test with O and H antisera. All 26 isolates showed susceptibility to amikacin (100%) and the majority of isolates showed high susceptibility to gentamicin (88.5%) and chloramphenicol (73.1%). But all isolates were resistant to penicillin. These results may provide the basic knowledge to establish strategies for the treatment and prevention of enteric disease in calves.