• Korean Journal of Veterinary Research
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• v.56 no.3
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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.

• Food Science of Animal Resources
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• v.40 no.4
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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.

• Food Science and Preservation
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• v.5 no.3
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• pp.286-291
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• 1998

The sensitivity of various pathogenic bacteria(Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus 196E, Salmonella typhimurium) to the water extract of green tea was tested. Tryptic soy broth was inoculated with 10$\^$5/CPU/ml of pathogenic bacteria and incubated at 35$^{\circ}C$ for 30 hours. The extract was added at a final concentration of 0-2%(w/v) into culture broth at the mid or late exponential phase of bacteria. The growth of pathogenic bacteria was inhibited with increasing concentrations of the extract in culture broth and the late exponential phase cells were more resistant than the mid exponential phase cells. Cram positive bacteria(L. monocytogenes and S. aureus 196E) were more sensitive than Cram negative bacteria(E. coli O157:H7 and S. typhimurium). S. aureus had the highest sensitivity, followed by L monocytogenes, E. coli O157:H7. S. typhimurium was the most resistant to the water extract of green tea.

• Korean Journal of Veterinary Service
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• v.15 no.2
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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.

• Journal of Environmental Health Sciences
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• v.38 no.1
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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.

• Food Science and Preservation
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• v.5 no.4
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• pp.380-385
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• 1998

The sensitivity of various pathogenic bacteria(Aeromonas hydrophila, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus 196E, Salmonella typhimurium) to the ethanol extract of pine needle was tested. Tryptic soy broth containing 0-2%(w/v) of the ethanol extract of pine needle was inoculated with 10$^4$-10$\^$6/ CFU/ml of pathogenic bacteria and incubated at 35$^{\circ}C$ for 48 hours. Gram positive bacteria(L. monocytogenes and S. aureus 196E) and 1 Gram negative bacteria(A. hydrophila) were more sensitive than E. coli O157:H7 and S. typhimurium in the ethanol extract of Pine needle. Gram negative bacteria(E. coli O157:H7 and S. typhimurium) were not inhibited at 1% and they were slightly inhibited at 2% ethanol extract of pine needle. S. aureus was the highest sensitivity, followed by A. hydrophila, L. monocytogenes E. coli O157:H7 in that order. S. typhimurium was the most resistant to the ethanol extract of pine needle.

• Korean Journal of Veterinary Research
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• v.55 no.1
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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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• v.59 no.2
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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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• v.27 no.1
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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.

• Biomedical Science Letters
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• v.17 no.1
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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.