This paper describes a fatal case of pneumonia in a 14-day-old dog caused by extraintestinal pathogenic Escherichia coli (ExPEC). The necropsy showed that almost all of left lobes of the lungs had dark-red consolidation. A histopathology examination revealed moderate acute fibrino-hemorrhagic necrotizing pneumonia with intralesional bacterial colonies. Non-suppurative epicarditis, congestion in the liver, and necrosis in the white pulp of the spleen also were found. E. coli with cytotoxic necrotizing factor 1 and α-hemolysin was isolated from the lung. This case was confirmed to have fatal pneumonia caused by ExPEC that led to a systemic infection.

Escherichia (E.) coli is commensal bacteria found in the intestine; however, some pathogenic strains cause diseases in animals and humans. Although E. coli does not typically produce hydrogen sulfide (H2S), H2S-producing strains of E. coli have been identified worldwide. The relationship between virulence and H2S production has not yet been determined. Therefore, characteristics of H2S-producing isolates obtained from swine feces were evaluated including antibiotic resistance patterns, virulence gene expression, and genetic relatedness. Rates of antibiotic resistance of the H2Sproducing E. coli varied according to antibiotic. Only the EAST1 gene was detected as a virulence gene in five H2S-producing E. coli strains. Genes conferring H2S production were not transmissible although the sseA gene encoding 3-mercaptopyruvate sulfurtransferase was detected in all H2S-producing E. coli strains. Sequences of the sseA gene motif CGSVTA around Cys238 were also identical in all H2S- producing E. coli strains. Diverse genetic relatedness among the isolates was observed by pulsed-field gel electrophoresis analysis. These results suggested that H2S-producing E. coli strains were not derived from a specific clone and H2S production in E. coli is not associated with virulence genes.

Avian pathogenic Escherichia coli (APEC) is a causative agent for a number of extra intestinal diseases and account for significant losses to the poultry industry. Since protective immunity against APEC is largely directed to virulence antigens, we have individually expressed four different viulence antigens, papA, papG, IutA, and CS31A, using an attenuated Salmonella Typhimurium and a plasmid pBB244. Following oral immunization of mice with combination of two or four of these strains, serum IgG and mucosal IgA responses were elicited against each antigen represented in the mixture. The antigen-specific mucosal IgA responses were significantly higher in the group of mice immunized with the heat-labile Escherichia coli enterotoxin B subunit (LTB) strain than those in the group of mice immunized without the LTB strain. While, there was no significant difference between these two groups in antigen-specific serum IgG responses. The results showed that LTB could act as mucosal immune adjuvant. To assess the nature of immunity, the distribution of antigen-specific IgG isotypes was analyzed. All groups promoted Th1-type immunity as determined by the IgG2a/IgG1 ratio. Thus, our findings provided evidence that immunization with a combination of several vaccine strains is one of the strategies of developing effective vaccines against APEC.

Among 203 avian pathogenic Escherichia coli (APEC) isolated from poultry with colibacillosis in korea, 14 isolates were selected from total 68 isolates transferred R plasmid and classified into 5 groups on the basis of antimicrobial minimal inhibitory concentration (MIC) pattern, farm source and O serotype. An association between clonal origin and R plasmid of them was investigated by R plasmid profile, restriction endonuclease analysis and pulsed-field gel electrophoresis (PFGE). The strains that showed the same or very similar antimicrobial MIC pattern, but different farm source and O serotype, revealed different PFGE pattern, which seemed to be different clonal origin. And the strains that showed the same MIC pattern and O serotype, revealed different PFGE pattern, seemed to be originated from different clone. Also the strains showing the same MIC pattern and farm source, but different O serotype, revealed to be different clonal origin. The strains that showed the same or similar MIC pattern, farm source, and O serotype, revealed identical or similar PFGE pattern, which seemed to belong to be one clone. Meanwhile, horizontal transfer of R plasmid seems to be common in APEC with regardless of O serotype and clone of the strains. These results indicate that rapid and accurate epidemiological survey of APEC can be possible by the combination of O serotyping, plasmid profiling and PFGE analysis following the classification of them into groups of antimicrobial drug resistance pattern.

The purpose of present study was to investigate the antimicrobial resistance in Escherichia coli isolated from healthy animals in all provinces of the Republic of Korea. A total of 2,085 E. coli strains isolated from 11,336 fecal samples of healthy animals during 2010-2012 were examined for antimicrobial resistance. Comparison of average resistance rate through the years revealed that tetracycline (47.0% and 76.1%) and streptomycin resistance (42.6% and 64.6%) was most frequently observed in cattle and pigs, respectively. Whereas, in chicken isolates, resistance against nalidixic acid (90.9%) was highest among the antimicrobials tested. Percentage of E. coli that showed multidrug resistance (resistance against¡� three subclasses of antimicrobial agents) was 17.6% (151/860) in cattle, 69.4% (506/729) in pigs, and 86.1% (427/496) in chickens. Overall, the rates of resistance are apparently different between animal species and, in particular, resistance was less prevalent in cattle than in pigs and chickens. In conclusion, this study showed higher prevalence of resistance in commensal E. coli strains to antimicrobial agents in Korean livestock and highlighted the urgent need for measures to regulate the abuse of antimicrobial agents.

The study evaluated whether a transgenic carrot vaccine could induce a K88-specific immune response in sows and whether the resultant maternal antibody could protect piglets against enterotoxigenic Escherichia coli (ETEC) K88ac infection. Sows (n = 15) selected randomly from a farm in Korea were assigned to three groups (n = 5 per group: control [untreated]), group A (orally inoculated with a non-transgenic and transgenic carrot vaccines at 2 and 4 weeks ante partum, respectively), and group B (conventionally vaccinated according to the manufacturer’s instructions). After 7 days of lactation, 5 piglets selected randomly from each group were challenged with 1 × 10∨10 colony forming units/mL ETEC K88ac. Group C had the lowest mean fecal consistency score on post-challenge days 1 and 7. Histiologically, On post-challenge day 7, group C showed an increased duodenum and ileum villus:crypt ratio, compared to group A in the duodenum, with group B displaying the highest ratio. Groups B and C had more increased villus width than group A in the jejunum. Group C displayed the greatest increase in villus width in the ileum. The colostrums and serum from groups B and C displayed higher concentrations of IgA and IgG against ETEC K88, compared to group A. Based on the results, it was concluded that the transgenic carrot vaccine in sow per oral may have an effect on preventing piglet diarrhea as good as commercial recombinant vaccine.

Shiga toxin-producing Escherichia coli (STEC) causes various clinical signs in human and animals, and has been indicated as a global enteropathogen with zoonotic importance. In this study, the feces of healthy pigs were collected from the slaughtered pigs of Daejon abattoir during the period from December 2001 to October 2002. Of 326 specimens, 13 STEC were confirmed by culture, PCR and colony hybridization. The isolates were further studied for toxin types, pathogenic factors, plasmid profiles, and antimicrobial resistance to characterize the genetic and toxigenic properties.

The isolation rate of Escherichia (E.) coli in poultry litter was investigated at 44 broiler farms, 20 that used fresh litter and 24 that used recycled litter. The patterns of resistance to antibiotics of the E. coli isolates were compared. In litter sampled before the rearing period, the isolation rate of E. coli was higher at farms that used fresh litter; E. coli was present in the litter in 94.5% (35 out of 37 flocks tested) of the farms that used fresh litter vs. 51.2% (21 out of 41 flocks) of the farms that used recycled litter. The susceptibility of the 93 isolates of E. coli to 13 antibiotics was studied. Before the rearing period, E. coli isolates from the farms that recycled litter showed higher resistance rates than isolates from farms that replaced litter with fresh litter. Comparing the antibiotic resistance patterns of isolates from litter sampled before and at the end of the rearing period, the antibiotic resistance rates at the end of the rearing period increased dramatically compared with rates before the rearing period.

Oregano (Origanum vulgare) is an aromatic herb belonging to the Lamiaceae family. This study evaluated the therapeutic effect of oregano essential oil (OEO) on clinical bovine mastitis caused by Staphylococcus (S.) aureus and / or Escherichia (E.) coli. Thirty - two quarters from 18 lactating cows with subclinical mastitis were selected from a dairy farm and were divided into 4 groups (8 quarters / group): negative control (CON), positive control (GEN) and two OEO-treated groups (OEO-1 and OEO-2). Each group was intramammarily treated with saline, 10 g/tube of gentamicin ointment, and single and double doses of 0.9 mL OEO ointment twice a day for three days, respectively. After the treatments, physical udder conditions were greatly improved in GEN and OEO groups. In CON group, somatic cell counts (SCCs), number of white blood cells (WBC) and bacteria were increased. However, in OEO groups, SCCs and number of WBC were significantly decreased and S. aureus and E. coli were not detected in milk as compared with those before the treatments as well as GEN group. These results suggest that OEO may be a useful alternative to antibiotics for the control of subclinical bovine mastitis caused by S. aureus and/or E. coli.

Antimicrobial resistance is one of the most concerns in pig industry. Escherichia (E.) coli have been used for the indicator to monitor the antimicrobial resistance. In this study, 321 E. coli from diarrheic and non-diarrheic piglets were tested for antimicrobial resistance and frequency of Bla∧TEM. In non-diarrheic piglets, they were resistant to oxytetracycline (93%), streptomycin (92%) and sulfadiazine (90%) but susceptible to ceftiofur (99%), colistin (97%), and enrofloxacin (82%). The isolates from diarrheic piglets were resistant to enrofloxacin (72.9%), ceftiofur (17.6%), and colistin (11.3%), whereas the resistance was 1%, 18% and 3% in case of non-diarrheic piglets, respectively. The resistance for amoxicillin/clavulanic acid (54.1%) and ceftiofur (22%) was high in isolates from post-weaning piglets. The resistance for colistin was 15.2% in nursery piglets. Seventy-three percent of isolates from diarrheic piglets showed high multidrug resistance profile (more than 13 antimicrobials) compared to those from non-diarrheic pigs in which 71% of isolates showed moderate multidrug resistance profile (7 to 12 antimicrobials). The frequency of Bla∧TEM in E. coli from non-diarrheic and diarrheic piglets was 57% and 69%, respectively. The results might provide the basic knowledge to establish the strategies for treatment and reduce antibiotic resistance of E. coli in piglets.