• Journal of Food Hygiene and Safety
• /
• v.32 no.2
• /
• pp.129-134
• /
• 2017

Diarrheagenic Escherichia coli is now recognized as an important cause of diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome (HUS) worldwide. E. coli were isolated from 80 of 356 (22.5%) chicken and chilled chicken products in Korea. Fifteen virulence genes specific for pathogenic E. coli, including Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC), were examined by multiplex PCR. STEC virulence markers were detected for eaeA (20.0%), escV (21.3%), stx1 (3.8%), ent (2.5%), EHEC-hly (1.3%), stx2 (1.3%), EAEC virulence marker (astA) was detected in 32.5%. ETEC and EIEC were not detected. STEC serotypes O152, O1, O116, O26, O25, O119 and O153 were found in chicken samples. This suggests the importance of diarrheagenic Escherichia coli control in raw chicken and chilled chicken food for food safety.

• Annals of Laboratory Medicine
• /
• v.38 no.6
• /
• pp.555-562
• /
• 2018

Background: The emerging mobile colistin resistance gene, mcr-1, is an ongoing worldwide concern and an evaluation of clinical isolates harboring this gene is required in Korea. We investigated mcr-1-possessing Enterobacteriaceae among Enterobacteriaceae strains isolated in Korea, and compared the genetic details of the plasmids with those in Escherichia coli isolates from livestock. Methods: Among 9,396 Enterobacteriaceae clinical isolates collected between 2010 and 2015, 1,347 (14.3%) strains were resistant to colistin and those were screened for mcr-1 by PCR. Colistin minimum inhibitory concentrations (MICs) were determined by microdilution, and conjugal transfer of the mcr-1-harboring plasmids was assessed by direct mating. Whole genomes of three mcr-1-positive Enterobacteriaceae clinical isolates and 11 livestock-origin mcr-1-positive E. coli isolates were sequenced. Results: Two E. coli and one Enterobacter aerogenes clinical isolates carried carried IncI2 plasmids harboring mcr-1, which conferred colistin resistance (E. coli MIC, 4 mg/L; E. aerogenes MIC, 32 mg/L). The strains possessed the complete conjugal machinery except for E. aerogenes harboring a truncated prepilin peptidase. The E. coli plasmid transferred more efficiently to E. coli than to Klebsiella pneumoniae or Enterobacter cloacae recipients. Among the three bacterial hosts, the colistin MIC was the highest for E. coli owing to the higher mcr-1-plasmid copy number and mcr-1 expression levels. Ten mcr-1-positive chicken-origin E. coli strains also possessed mcr-1-harboring IncI2 plasmids closely related to that in the clinical E. aerogenes isolate, and the remaining one porcine-origin E. coli possessed an mcr-1-harboring IncX4 plasmid. Conclusions: mcr-1-harboring IncI2 plasmids were identified in clinical Enterobacteriaceae isolates. These plasmids were closely associated with those in chicken-origin E. coli strains in Korea, supporting the concept of mcr-1 dissemination between humans and livestock.

• Journal of Life Science
• /
• v.31 no.8
• /
• pp.755-760
• /
• 2021

Swine diarrhea is a livestock disease that causes huge economic losses to pig farms. In general, diarrhea occurs because of the proliferation of pathogenic Escherichia coli (E. coli). The toxins produced by the proliferated E. coli cause edema in pigs. Although the proliferation of these coliforms can be prevented by using a vaccine, the vaccines containing chemically produced dead bacteria are not very effective, making it difficult to control the proliferation of E. coli. Therefore, there is a need to develop new, more effective vaccines. In this study, we prepared killed F4+ and F18ab+ E. coli, which induce diarrhea and edema in pigs, using the extracts of immune-induced silkworms containing antimicrobial peptides and examined their availability as a killed-bacteria vaccine. First, the antimicrobial activity analysis of the prepared immune-induced silkworm extract was conducted using the radial diffusion assay. The results showed high activity against both F4+ and F18ab+ E. coli. The production efficiency of E. coli dead cells was determined using the colony-counting method. The concentration of the E. coli dead cells was the highest (50 mg/ml) when treated at 4℃. In addition, the analysis of the prepared dead cells using a transmission electron microscope confirmed that E. coli leaked out of the cytoplasm and the cell membrane remained intact. Therefore, F4+ and F18ab+ E. coli produced using immune-induced silkworms extract are considered to be highly available as bacterial ghost vaccines that can help prevent swine diarrhea and the resulting edema.

• Korean Journal of Veterinary Service
• /
• v.44 no.4
• /
• pp.271-281
• /
• 2021

Pathogenic Escherichia coli (E. coli) is one among the most important agents of diarrhea in calves. From January to December 2021, 108 isolates from feces of calves with diarrhea were investigated for enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), shiga toxin-producing E. coli (STEC), enteroaggregative E. coli (EAEC), and enteroinvasive E. coli (EIEC) using real-time PCR. In addition, the genes for F5, F17 and F41 fimbriae were detected by PCR. The most frequently isolated pathotypes were EPEC/STEC (29 isolates), and ETEC/EPEC/STEC (29 isolates). ETEC/EPEC, and ETEC/STEC were also found in 10 isolates. EPEC, STEC, and ETEC were detected in 13, 11, and 6 respectively. EAEC, and EIEC was not detected. Antimicrobial resistance test was carried out by agar disc diffusion method with 14 antimicrobials. Among 108 pathogenic E. coli isolates, 107 isolates were resistant to at least one of 14 antibiotics used in this study, 99 (91.7%) were resistant to two or more antimicrobials, and a single remarkable isolate was resistant to 14 antimicrobials. The isolates were primarily resistant to penicillins, streptomycin, tetracycline, ceftiofur, Trimethoprim/sulfamethoxazole, Kanamycin, and Ciprofloxacin. The high rate of resistance in pathogenic E. coli, sometimes to multiple drugs, may complicate future options for treating human infections. These results may bu used for diagnosis and therpeitic purposes in calves with diarrhea.

• Molecules and Cells
• /
• v.20 no.1
• /
• pp.142-150
• /
• 2005

Members of the multifunctional Cyp family have been isolated from a wide range of organisms. However, few functional studies have been performed on the role of these proteins as chaperones in red alga. For studying the function of cDNA GjCyp-1 isolated from the red alga (Griffithsia japonica), we expressed and purified a recombinant GjCyp-1 containing a hexahistidine tag at the amino-terminus in Escherichia coli. An expressed fusion protein, $H_6GjCyp-1$ maintained the stability of E. coli proteins up to $50^{\circ}C$. For a functional bioassay for recombinant $H_6GjCyp-1$, the viability of E. coli cells overexpressing $H_6GjCyp-1$ was compared with that of cells not expressing $H_6GjCyp-1$ at $50^{\circ}C$. After high temperature treatment for 1 h, E. coli overexpressing $H_6GjCyp-1$ survived about three times longer than E. coli lacking $H_6GjCyp-1$. Measurement of the light scattering of luciferase (luc) showed that GjCyp-1 prevents the aggregation of luc during mild heat stress and that the thermoprotective activity of GjCyp-1 is blocked by cyclosporin A (CsA), an inhibitor of Cyps. Furthermore, the Cyp-CsA complex inhibited the growth of E. coli under normal conditions. The results of the GjCyp-1 bioassays as well as in vitro studies strongly suggest that Cyp confers thermotolerance to E. coli.

• Journal of Environmental Health Sciences
• /
• v.46 no.3
• /
• pp.353-358
• /
• 2020

Objectives: An outbreak of pathogenic Escherichia coli food poisoning in Korea was first reported in 1998. They have continued to occure since then. This study was performed to describe the long-term trend in pathogenic E. coli food poisoning occurrences in Korea and examine the relation with climate factors. Methods: Official Korean statistics on food poisoning outbreaks and meteorological data for the period 2002-2017 were used. Pearson's correlation analysis was employed to establish the relationship between outbreaks of pathogenic E. coli food poisoning and meteorological factors. The influence of meteorological factors upon the outbreaks was analyzed by regression analysis. Results: During the study period, pathogenic E. coli food poisoning ranked second for the number of outbreaks (excluding unknowns) and first for the number of cases. Average temperature, the highest and lowest temperatures, precipitation, number of days with rainfall, and humidity all had a significant correlation with monthly number of outbreaks of pathogenic E. coli food poisoning (p<0.001). It was found that the lowest and highest temperatures and precipitation had a significant influence on the monthly number of outbreaks of food poisoning (p<0.001). These variables together explained 42.1% of the total variance, with the lowest temperature having the greatest explanatory power. Conclusion: These results show that food poisoning incidences may have been influenced by climate change, especially warming. The results also suggest that pathogenic E. coli infections are now an important public health issue in Korea since it is one of the countries where climate change is occurring rapidly.

• Korean Journal of Veterinary Research
• /
• v.37 no.4
• /
• pp.779-784
• /
• 1997

A comprehensive study of 132 Escherichia coli isolates from 150 piglets with colibacillosis included detection of heat-labile enterotoxin, heat-stable enterotoxin, and identification of K88 (F4), K99 (F5), 987P (F6), and F41. Four pili were examined by haemagglutination and slide agglutination test. Heat-labile(LT) and heat-stable(ST) enterotoxin was determined by reverse passive latex agglutination and precipitation test, respectively. Among 132 E coli isolates, 26 had K88 (19.7%), 16 had K99 (12.1%), 3 had 987P (2.3%), and 2 had F41 (1.5%). Three had K88 and K99 (2.3%), 3 had K88 and 987P (2.3%), 2 had K99 and 987P (1.5%), 5 had K99 and F41 (3.8%), and 8 E coli strains had K88, K99 and F41 (6.1%) simultaneously. Among 132 E coli isolates, 5 produced LT only (3.8%), 55 produced heat-stable toxin ST only (41.7%), and 4 produced both LT and ST (3.0%). Three major pathotypes accounted for 27.9% of E coli isolates: $K99^+$ (8.3%), $K88^+ST^+$ (9%) and $K88^+$ (10.6%). Results of this study indicated that piliated enterotoxin-producing E coli was prevalent and was associated with diarrhea in preweaning piglets.

• Korean Journal of Microbiology
• /
• v.32 no.3
• /
• pp.192-197
• /
• 1994

Pseudomonas fluorescens which is able to utilize malonate as a sole carbon source was found to contain a novel 60 kb plasmid, which encodes the genes for the proteins to assimilate malonate, including malonate decarboxylase and acetyl-CoA synthetase. The evidence is as follows: The Pseudomonas cured with mitomycin C was unable to grow on malonate-medium as well as it lost plasmid. The plasmid isolated from the Pseudomonas could be introduced into E. coli strain JM103 and DH1 by transformation. The transformed E. coli was able to grow on malonate-medium and could transmit its plasmid back to the cured P. fluorescens by conjugation. The existence of the plasmid in the transformed E. coli was confirmed by hybridization with a labeled probe prepared from 12 kb segment of the plasmid. Dot hybridization showed that the copy number of the plasmid in the transformed E. coli is at least 13 times higher than in the wild type P. fluorescens. The two key enzymes, malonate decarboxylase and acetyl-CoA synthetase, were inducible by malonate in the transformed E. coli.

• The Korean Journal of Mycology
• /
• v.32 no.2
• /
• pp.145-147
• /
• 2004

The ethyl acetate extracts from the liquid cultures of Coriolus versicolor, Phellinus linteus, and Hericium erinaceus showed significant antibacterial activities against Escherichia coli K88, E. coli K99, E. coli 987P, and Salmonella typhimurium 14058 causing bacterial diarrhea in Korean house pigs and chicken. Of these extracts, Coriolus versicolor extract showed the highest antibacterial activity. In addition, these extracts also showed significant growth inhibition against Staphylococcus aureus CARM3230 and E. coli CARM1381 which are known as kanamycin and ampicillin-resistant strains. These results showed that the mushroom extracts could be developed as a livestock feed additives that can replace commercial antibiotics, and also could be good resources for the development of a new antibacterial agent.

• Applied Biological Chemistry
• /
• v.46 no.1
• /
• pp.7-11
• /
• 2003

Cloning and expression of copper-binding peptide gene in E. coli was carried out to enhance the copper-chelation capacity. E. coli was transformed with pET vector containing the copper-binding region of potato polyphenol oxidase gene and polyhistidine-coding DNA, and the copper content of E. coli harboring each vector was measured. No increase in intracellular copper was observed in E. coli harboring PPOCBpET32 vector, which contains DNA for polyphenol oxidase copper-binding region. Intracellular copper content of E. coli harboring pE728a vector, which contains one hexahistidine unit DNA, was 2,500 ppm after culturing without kanamycin, whereas E. coli harboring pET-his vector, which contains nine hexahistidine unit DNAs was 3,200 ppm.