• 대한수의학회지
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• 제56권3호
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• pp.167-176
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• 2016

We investigated whether maternal antibodies (mAbs) elicited by dams immunized with recombinant vaccine candidates against avian pathogenic Escherichia coli (APEC) can passively confer protective immunity to chicks. In the present study, pBP244 plasmids carrying selected antigens of APEC were transformed into Salmonella Typhimurium JOL912, which was used as a vaccine candidate against APEC. The hens were immunized with the vaccine candidates using prime or booster doses. The levels of IgG and sIgA specific to the selected antigens increased significantly following prime immunization. To evaluate the persistence of passively transferred mAbs, the levels of IgY and IgA were determined in egg yolks and whites, respectively. The eggs from the immunized group showed consistently increased levels of IgY and IgA until week 16 post-laying (PL) and week 8 PL, respectively, relative to the control group. The presence of mAbs was observed in chicks that hatched from the hens, and titers of plasma IgY were consistently raised in those from the immunized hens by day 14 post-hatching. Further, chicks from the immunized hens were protected from challenge with a virulent APEC strain, whereas those from non-immunized hens showed acute mortality.

• 한국축산식품학회지
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• 제40권4호
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• pp.668-674
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• 2020

Manuka honey (MH) has been shown anti-bacterial activity against several pathogenic bacteria. However, the inhibitory effect of MH on biofilm formation by Escherichia coli O157:H7 has not yet been examined. In this study, MH significantly reduced E. coli O157:H7 biofilm. Moreover, pre- and post-treatment with MH also significantly reduced E. coli O157:H7 biofilm. Cellular metabolic activities exhibited that the viability of E. coli O157:H7 biofilm cells was reduced in the presence of MH. Further, colony forming unit of MH-treated E. coli O157:H7 biofilm was significantly reduced by over 70%. Collectively, this study suggests the potential of anti-biofilm properties of MH which could be applied to control E. coli O157:H7.

• 한국식품저장유통학회지
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• 제5권3호
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• pp.286-291
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• 1998

4종류의 식중독세균(Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus 196E, Salmonella typhimurium)에 대하여 녹차 물추출물에 의한 항균작용을 조사하였다. 각 식중독세균을 tryptic soy broth(TSB)에 약 $10^{5}$CFU/ml 정도 되게 접종하여 35$^{\circ}C$에서 30시간 배양하였다. 세균의 배양중 대수증식기의 중기 혹은 말기에 녹차 물추출물을 0-2%(w/v)의 농도로 첨가하였을 때 증식억제 정도를 생균수 변화로서 비교하였다. 식중독세균의 증식은 첨가한 녹차 물추출물의 농도에 비례하여 억제되었으며 대수증식기 말기의 세균이 중기의 세균에 비하여 녹차 물추출물에 대한 내성이 컸다. Gram 양성균(L. monocytogenes, S. aureus)의 경우가 Gram 음성균(E. coli O157:H7, S. typhimurium)에 비하여 녹차 물추출물에 의한 억제효과는 월등히 컸다. 녹차 물추출물에 의한 증식억제 효과의 크기는 S. aureus, L. monocytogenes, E. coli O157:H7의 순이었으며 S. typhimurium에서 가장 강한 내성을 나타내었다.다.

• 한국동물위생학회지
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• 제15권2호
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• pp.134-143
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• 1992

The present study was conducted to investigate the biochemical characteristics and anti-biotic resistance of Escherichia coli(E. coli) isolated from piglets with diarrhea in Kyongbuk province during the Period from February to November 1991. 368 E. coli strains were isolated from 382 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. Tetracycline and sulfadimethoxine were found to be highly ineffective at in vitro inhibition of the E. coli of piglets origin. The majority of E. coli were susceptible to amikacin, chloramphenicol and gentamicine. 89 (89.0%) of 100 strains of E. coil were resistant to one or more drugs. The organisms resistant to 20 or 3 drugs were 54(60.6%) of 89 strains, whereas 16(17.9%) strains were found to be resistant to one drug. 55(61.8%) out of 89 drug resistance strains carried R factors($R^+$) which were transfer-able to the recipients by conjugation.

• 한국환경보건학회지
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• 제38권1호
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• pp.73-81
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• 2012

Objectives: With the goal of quantifying the risk of children contracting gastroenteritis while playing at interactive waterscape facilities and evaluating the adequacy of current water quality regulations, risk assessment was performed with Escherichia coli as pathogen. Methods: Abundances of E. coli in the waters of interactive water features in South Korea were acquired from survey reports. A gamma distribution describing the volume of water swallowed by children during swimming activities was adopted. Exposure rate and risk were calculated by Monte Carlo simulation and dose-response models for various pathogenic E. coli. Results: E. coli was detected in 25 out of 40 facilities, with range of ~1,600 CFU/100 ml. The abundance fitted an exponential distribution. Simulated exposures ranged ${\sim}1.9{\times}10^{10}$ CFU, varying greater along E. coli abundance than the volume of water. Risk of children being infected by enterohemorrhagic E. coli was high, with range of ~0.85. When E. coli abundance was <200 CFU/100 ml, which is the current government threshold, the risk decreased to <0.43. Although the guideline successfully reduced the risk of adults being infected by a less virulent E. coli strains (<0.03), the risk for children could not be quantified due to lack of dose-response models for those pathogens for children. Conclusions: Under the current guideline, children are at risk of being infected if water is contaminated with by enterohemorrhagic E. coli. For other E. coli strains, the risk appears to be considerably less. The result warrants need for developing dose-response models for children for each pathogenic E. coli strain.

• 한국식품저장유통학회지
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• 제5권4호
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• pp.380-385
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• 1998

5종류의 식중독세균 (Aeromonas hydrophila, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus 196E, Salmonella typhimurium)에 대하여 솔잎 ethanol 추출물의 항균작용을 조사하였다. 솔잎 ehanol 추출물을 0-2% (w/v) 함유한 tryptic soy broth(TSB)에 각 식중독세균을 약 $10^4$-$10^{6}$ CFU/ml 정도 되게 접종하여 35$^{\circ}C$에서 48시간 배양하면서 증식억제 정도를 생균수 변화로서 비교하였다. Gram 양성균인 L. monocytogenes, S. aureus와 Gram 음성균인 A. hydrophila는 솔잎 ehanol 추출물에서는 0.5% 이상의 농도에서 증식이 억제되어 솔잎 ethanol 추출물의 항균활성이 우수하였다. 그러나 Gram 음성균인 E. coli O157:H7과 S. typhimurium은 2%의 솔잎 ethanol 추출물에서 약간 증식이 억제되었으나 대체로 두 균주 모두 솔잎 ethanol 추출물에 대하여 강한 내성을 나타내었다. 솔잎 ethanol 추출물에 의한 증식억제 효과는 S. aureus > A. hydrophila> L. monocytogenes > E. coli O157:H7의 순으로 나타났으며 S. typhimurium에서 가장 강한 내성을 나타내었다.

• 대한수의학회지
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• 제55권1호
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• pp.31-39
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• 2015

The present study was conducted to determine the full rpoB and eight house-keeping gene sequences of 78 and 35, respectively, avian pathogenic E. coli (APEC) strains. Phylogenetic comparison with 66 E. coli and Shigella strains from GenBank and EMBL was also conducted. Based on the full rpoB sequence, 50 different rpoB sequence types (RSTs) were identified. RST 1 was assigned to a major RST that included 34.7% (50/144) of the analyzed strains. RST 2 to RST 50 were then assigned to other strains with higher nucleotide sequence similarity to RST 1 in order. RST 1, 11, and 23 were mixed with APEC along with human commensal and pathogenic strains while RST 2, 6, 9, 13-15, 22, 24, 25, 33, 34, 36, and 41 were unique to APEC strains. Only five APEC strains grouped into RST 32 and 47, which contained human pathogenic E. coli (HPEC). Thus, most of the APEC strains had genetic backgrounds different from HPEC strains. However, the minor APEC strains similar to HPEC should be considered potential zoonotic risks. The resolution power of multi-locus sequence typing (MLST) was better than RST testing. Nevertheless, phylogenetic analysis of rpoB was simpler and more economic than MLST.

• Journal of Animal Science and Technology
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• 제59권2호
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• pp.4.1-4.5
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• 2017

Background: Biofilms were the third-dimensional structure in the solid surface of bacteria. Bacterial biofilms were difficult to control by host defenses and antibiotic therapies. Escherichia coli (E. coli) and Salmonella were popular pathogenic bacteria that live in human and animal intestines. Essential oils are aromatic oily liquids from plant materials and well known for their antibacterial activities. Method: This study was conducted to determine effect of essential oil on anti-biological biofilm formation of E. coli and Salmonella strains in in vitro experiment. Two kinds of bacterial strains were separated from 0.2 g pig feces. Bacterial strains were distributed in 24 plates per treatment and each plates as a replication. The sample was coated with a Bacterial biofilm formation was. Result: Photographic result, Escherichia coli (E. coli) and Salmonella bacteria colony surface were thick smooth surface in control. However, colony surface in blended and single essential oil treatment has shown crack surface layer compared with colony surfaces in control. Conclusion: In conclusion, this study could confirm that essential oils have some interesting effect on anti-biofilm formation of E. coli and Salmonella strains from pig feces.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.67-71
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• 2017

This study examined the antimicrobial activity of flaxseed meal extract (FME) against Staphylococcus aureus and Escherichia coli O157:H7 inoculated on red mustard. With the treatment of 0.7% FME for 3 min, the reduction levels of S. aureus and E. coli O157:H7 populations were 1.23 and 1.83 log CFU/g, respectively. In addition, the combined treatment of 0.7% FME at $50^{\circ}C$ for 3 min reduced the populations of the pathogenic bacteria by 2.28 and 2.41 log CFU/g, respectively. The color and the vitamin C content were not significantly different between treatments. Thus, FME can be used as a novel antimicrobial agent in fresh-cut vegetables.

• 대한의생명과학회지
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• 제17권1호
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• pp.7-12
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• 2011

Free-living amoebae ingest several kinds of bacteria. In other words, the bacteria can survive within free-living amoeba. To determine how Escherichia coli K1 isolate causing neonatal encephalitis and non-pathogenic K12 interact with free-living amoebae, e.g., Acanthamoeba castellanii (T1), A. astronyxis (T7), Naegleria fowleri, association, invasion and survival assays were performed. To understand pathogenicity of free-living amoebae, in vitro cytotoxicity assay were performed using murine macrophages. T1 destroyed macrophages about 64% but T7 did very few target cells. On the other hand, N. fowleri which needed other growth conditions rather than Acanthamoeba destroyed more than T1 as shown by lactate dehydrogenase (LDH) release assay. In association assays for E. coli binding to amoebae, the T7 exhibited significantly higher association with E. coli, compared with the T1 isolates (P<0.01). Interestingly, N. fowleri exhibited similar percentages of association as T1. Once E. coli bacteria attach or associate with free-living amoeba, they can penetrate into the amoebae. In invasion assays, the K1 (0.67%) within T1 was observed compared with K12 (0%). E. coli K1 and K12 exhibited high association with N. fowleri and bacterial CFU. To determine the fate of E. coli in long-term survival within free-living amoebae, intracellular survival assays were performed by incubating E. coli with free-living amoebae in PBS for 24 h. Intracellular E. coli K1 within T1 (2.5%) and T7 (1.8%) were recovered and grown, while K12 were not found. N. fowleri was not invaded and here it was not recovered.