• Korean Journal of Veterinary Service
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• v.46 no.1
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• pp.35-45
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• 2023

Pathogenic Escherichia coli is the cause of a wide range of diseases in pigs, including diarrhea, edema disease, and septicemia. Diarrhea caused E. coli may result in significant economic losses, making pathogenic E. coli an important pathogen for the swine industry. This study investigated the prevalence of virulence factor genes, antimicrobial resistance phenotypes, and resistance genes in E. coli isolated from feces of piglets in Korea between 2017 and 2020. As a result, 119 pathogenic E. coli isolates were obtained from 601 fecal samples. The F4 adhesin gene and the STb enterotoxin gene were commonly present in E. coli isolated from diarrhea samples. The dominant virulotypes of isolates from diarrhea samples were STb, Stx2e, and F4:LT:STb. More than 80% of the screened isolates were resistant to ampicillin, sulfisoxazole, chloramphenicol, or tetracycline. To confirm the resistance mechanisms for β-lactam or quinolone, we investigated the genotypic factors of resistance. Each of the ceftiofur-resistant E. coli produced an extended-spectrum β-lactamase encoded by bla_CTX-M-14, bla_CTX-M-27, and bla_CTX-M-55. And all ciprofloxacin-resistant E. coli harbored mutations in quinoloneresistance-determining-regions. In addition, some of the ciprofloxacin-resistant E. coli contained the plasmid-mediated-quinolone-resistance genes such as qepA, qnrB1, or qnrD. This study has confirmed that the F4 fimbria and the STb enterotoxin are the most predominant in pathogenic E. coli isolated from piglets with diarrhea in Korea and there is a great need for responsible and prudent use of antimicrobials to treat colibacillosis.

• Korean Journal of Veterinary Service
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• v.16 no.2
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• pp.150-156
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• 1993

The present study was conducted to investigate the biochemical characteristics and anti-biotic resistance of pathogenic Escherichia coli (E. coli) isolated from piglets with diarrhea in Kyongbuk Western Area during the period from February to November 1992. 55 E. coli strains were isolated from 97 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. The majority of E. coli were susceptible to amikacln, enrofloxacin and gentamicin. 51 (92.7%) out of 55 drug resistance stains carried R factor (R+) which were transferable to the recipients by conjugation.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.975-987
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• 2016

Lactobacillus plantarum (L. plantarum) is a representative probiotic. In particular, L. plantarum is the first commensal bacterium to colonize the intestine of infants. For this reason, the initial settlement of L. plantarum can play an important role in determining an infant's health as well as their eventual health status as an adult. In addition, L. plantarum combats pathogenic infections (such as Escherichia coli (E. coli), one of the early pathogenic colonizers in an unhealthy infant gut) by secreting antimicrobial substances. The aim of this research was to determine how L. plantarum combats E. coli infection and why it is a representative probiotic in the intestine. Consequently, this research observed that E. coli releases uracil. L. plantarum specifically recognizes E. coli-derived uracil, which increases the growth rate and production of antimicrobial substance of L. plantarum. In addition, through the inhibitory activity test, this study postulates that the antimicrobial substance is a protein and can be considered a bacteriocin-like substance. Therefore, this research assumes that L. plantarum exerts its antibacterial ability by recognizing E. coli and increasing its growth rate as a result, and this phenomenon could be one of the reasons for L. plantarum settling in the intestine of infants as a beneficial bacterium.

• Korean Journal of Veterinary Research
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• v.48 no.2
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• pp.145-151
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• 2008

This study was conducted to investigate biochemical properties and O group serotypes of pathogenic 203 Escherichia (E.) coli isolates from poultry with collibacillosis in Korea during the period from April 2003 to December 2005. Biochemical and fermentative properties of 203 isolates of E. coli tested were in accordance with Cowan and Steel's classification standard. One hundred and forty one isolates (69.5%) could be classified into a total of 20 O serotypes. Among them, the predominant O groups were O78 (32.5%), O88 (7.8%), O15 (6.8%), O141 (6.4%), and O158 (3.0%) in decreased order. Other infrequently encountered serogroups included : O8 (2%), O161 (2%), O20 (1.5%), O125 (1.5%), O2 (1%). And O6, O18, O24, O46, O76, O109, O119, O138, O139 and O148 had a frequency of 0.5%, respectively. Sixty two isolates (30.5%) were non-typeable with standard 173 O antisera used in this study.

• Genomics & Informatics
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• v.15 no.2
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• pp.69-80
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• 2017

In this study, cytolethal distending toxin (CDT) producer isolates genome were compared with genome of pathogenic and commensal Escherichia coli strains. Conserved genomic signatures among different types of CDT producer E. coli strains were assessed. It was shown that they could be used as biomarkers for research purposes and clinical diagnosis by polymerase chain reaction, or in vaccine development. cdt genes and several other genetic biomarkers were identified as signature sequences in CDT producer strains. The identified signatures include several individual phage proteins (holins, nucleases, and terminases, and transferases) and multiple members of different protein families (the lambda family, phage-integrase family, phage-tail tape protein family, putative membrane proteins, regulatory proteins, restriction-modification system proteins, tail fiber-assembly proteins, base plate-assembly proteins, and other prophage tail-related proteins). In this study, a sporadic phylogenic pattern was demonstrated in the CDT-producing strains. In conclusion, conserved signature proteins in a wide range of pathogenic bacterial strains can potentially be used in modern vaccine-design strategies.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.543-552
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• 2020

For efficient prevention and treatment of enteric colibacillosis, understanding about latest virulence factors and antimicrobial resistance of Escherichia coli is essentially needed. The aim of this study was to survey antimicrobial resistance and determine the prevalence of fimbriae and enterotoxin genes among 118 pathogenic E. coli isolates obtained from Korean pigs with diarrhea between 2016 and 2017. The genes for the toxins and adhesins were amplified by polymerase chain reaction (PCR). The susceptibility of the E. coli isolates to antimicrobials were tested using the standard Kirby-Bauer disk diffusion method. The most prevalent fimbrial antigen was F18 (40.7%), followed by F4 (16.9%), and the most prevalent combinations of toxin genes were Stx2e (21.2%), STb:EAST-1 (19.5%), and STa:STb (16.9%), respectively. Among the pathotypes, enterotoxigenic E. coli (ETEC) was the most predominant (67.8%), followed by Shiga-toxin producing E. coli (STEC, 23.7%). We confirmed high resistance rates to chloramphenicol (88.1%), tetracycline (86.4%), streptomycin (86.4%), and ampicillin (86.4%). And the majorities of isolates (90.7%) showed multi-drug resistance which means having resistance to 3 or more subclasses of antimicrobials. Results of this study can be a source of valuable data for investigating the epidemiology of and control measures for enteric colibacillosis in Korean piggeries.

• Preventive Nutrition and Food Science
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• v.12 no.3
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• pp.135-140
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• 2007

Antibacterial activities of the major phenolic components from Camellia sinensis L. were investigated against several pathogenic microorganisms including Gram-positive strains like Staphylococcus aureus ATCC 29213 and Streptococcus pyogens 308A; and Gram-negative strains like Escherichia coli ATCC 25922, Escherichia coli 078, Pseudomonas aeruginosa 9027, and Enterobacter cloacae 1321E. The MIC values demonstrate that both (-)-epicatechin and (-)-epigallocatechin were more considerably toxic against Staphylococcus aureus ATCC 29213 than the other two catechins like (-)-epicatechingallate and (-)-epigallocatechin-3-gallate. (-)-Epicatechingallate and (-)-epigallocatechin-3-gallate were most inhibitory against Escherichia coli ATCC 25922. As a result, (-)-epicatechin showed predominant antibacterial activities among tea varieties. The contents of major polyphenolic components such as four catechins, theaflavin, and quercetin were different according to fermentation processes. The total contents of four catechins were ranged from 13.81 to 1.33%, with (-)-epigallocatechin-3-gallate being dominant among tea varieties; theaflavin was found the characteristic pigment in fully-fermented black tea.

• Korean Journal of Veterinary Research
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• v.60 no.3
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• pp.163-171
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• 2020

This study examined the prevalence of adherence factors, toxin genes, antimicrobial resistance phenotypes, and resistance genes in Escherichia coli (E. coli) isolated from piglets with diarrhea before and after the ban on antibiotic growth promoters (AGPs) in Korea from 2007 to 2018. In this period, pathogenic 474 E. coli isolates were obtained from diarrheic piglets. The virulence factors and antimicrobial resistance genes were assayed using a polymerase chain reaction, and the susceptibility to antibiotics was tested according to the Clinical and Laboratory Standards Institute guidelines. After the ban on AGPs, the frequency of F4 (12.5% to 32.7%) increased significantly, and LT (31.9% to 20.3%) and EAST-I (46.5% to 35.2%) decreased significantly. In addition, the resistance to streptomycin (45.8% to 67.9%), cephalothin (34.0% to 59.4%), and cefazlin (10.4% to 28.8%) increased significantly. Colistin resistance plasmid-mediated genes, mcr-1 and mcr-3, were detected after the ban on AGPs. The results of this study can provide useful data for analyzing the impact of the ban on AGPs on the virulence profiles and antimicrobial resistance of E. coli isolated from piglets with diarrhea in Korea.

• Korean Journal of Veterinary Research
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• v.48 no.3
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• pp.275-285
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• 2008

Antimicrobial drugs are widely used in poultry industry as growth promoters or to control infectious diseases. However, this practice is reported to have caused high resistance to antimicrobial drugs in normal chicken flora and pathogens. Antimicrobial resistance to Escherichia coli (E. coli) from chicken has been mainly reported in normal flora, but rare in pathogenic organism in Korea, recently. Therefore, this study was conducted to investigate prevalence of antimicrobials resistance, transfer of R plasmid, and association between antimicrobial drug resistance and O serotype of 203 pathogenic E. coli from poultry in Korea during the period from April 2003 to December 2005. These isolates showed a high resistance to tetracycline (Tc, 93.6%), nalidixic acid (Na, 92.6%), streptomycin (Sm, 81.8%), ampicillin (Ap, 77.3%), ciprofloxacin (Ci, 70.9%), sulfisoxazole (Su, 66.5%), and trimethoprim (Tp, 58.1%). Two hundred-one (99.0%) of the isolates were resistant to one or more drugs. They showed 57 different resistant patterns, and the most prevalent resistant pattern among them was Tc, Sin, Su, Ap, Tp, Ci, Na. Sixty-eight (33.8%) of the isolates transferred all or a part of their antimicrobial resistant pattern to the recipient strain by R plasmid. The most common antimicrobial resistant pattern was Tc, Sm, Su, Ap, Tp, Ci, Na in serotype O78, O88 and O15, respectively. These results exhibit high individual and multiple resistance to antimicrobials of pathogenic E. coli from poultry in Korea. They also suggest the needs for surveillance to monitor antimicrobial resistance in pathogenic bacteria that can be potentially transmitted to humans from food animals and to regulate the abuse of antimicrobials on food-producing animals in Korea.

• Korean Journal of Veterinary Research
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• v.49 no.3
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• pp.195-200
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• 2009

Avian pathogenic Escherichia coli (APEC) is an important bacterial pathogen of chickens and causes colibacillosis such as airsacculitis, perihepatitis, omphalitis, peritonitis, salpingitis, and pericarditis. As the transfer of antibiotic resistance from animal to humans can be possible, surveillance on antibiotic resistance of APEC is very important. A total 34 APEC isolates from diseased chickens during the period from 2007 to 2009 were obtained. The susceptibility of the isolates to 13 antibiotics was determined by disc diffusion assay. Resistance to erythromycin was found in 97.1% of APEC isolated, followed by resistance to tetracycline (85.3%), doxycycline (82.3%), ampicillin (73.5%), sulfisoxazole (67.6%), enrofloxacin (67.6%), ciprofloxacin (64.7%), norfloxacin (61.7%) trimethoprim/sulfamethoxazole (52.9%), gentamycin (26.5%), amoxicillin (8.8%), colistin (5.9%), and amikacin (2.9%). The blaTEM genes were detected in 25 (100%) of the 25 ampicillin-resistant APEC isolates. Among the 29 tetracycline-resistant APEC isolates, tetA and tetB genes were detected in 18 (62.1%) and 9 (31%) isolates, respectively. Twenty six (76.5%) isolates were multiresistant to at least 6 antibiotics and seven (20.1%) isolates were multiresistant to at least 10 antibiotics. This results indicated that multiple antibiotic-resistant APEC is widespread in chicken flocks in Korea.