• Korean Journal of Veterinary Research
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• v.62 no.1
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• pp.4.1-4.5
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• 2022

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.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.974-981
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• 2020

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a high-risk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPC-encoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

• Korean Journal of Veterinary Research
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• v.53 no.3
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• pp.163-167
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• 2013

Avian pathogenic Escherichia coli (APEC) are known to cause extraintestinal disease in poultry, leading to substantial losses in the industry. IutA, iron-regulated aerobactin receptor is firmly associated with APEC. To assess the potential of IutA to induce protective immune responses, attenuated Salmonella Typhimurium strain expressing IutA was constructed and administered orally to BALB/c mice. The IutA-specific immune responses were measured with sera, vaginal and fecal samples by an enzyme-linked immunosorbent assay. We found that the Salmonella-IutA vaccine induced significantly higher immune responses as compared to the control inoculated with the attenuated S. Typhimurium containing the plasmid only. The IutA-specific immune responses were increased by second immunization at third week after initial immunization, whereas triple immunization induced lower immune responses than those induced by the double immunization. The Salmonella-IutA vaccine induced a nature of immunity biased to the Th1-type, as judged by the ratio of IutA-specific IgG isotypes (IgG2a/IgG1). Overall, these results suggest that the Salmonella-IutA vaccine appear to be suitable candidate for a vaccine against APEC.

• Journal of Veterinary Clinics
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• v.28 no.3
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• pp.297-302
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• 2011

Avian pathogenic Escherichia coli (APEC) causes a number of extraintestinal diseases in poultry. A virulence factor, P-fimbriae is firmly associated with the diseases. In this study, to develop an effective vaccine for the prevention of APEC, recombinant attenuatted Salmonella Typhimurium vaccines expressing PapA and PapG of P-fimbriae were evaluated whether these induced protective immune responses in murine models. Female BALB/c mice were primed and boosted orally at 7 and 10 weeks of age. In all immunized mice, the antigen-specific serum IgG levels were remained higher than those in the control mice from the fourth week post inoculation till the end of this study. In addition, antigen-specific serum IgG levels in the prime-booster immunized mice were enhanced as compared to the single immunized mice among each immunized group. The antigen-specific mucosal IgA levels in the mice immunized with each strain also induced higher than those in control mice. In addition, serum IgG and fecal IgA levels in mice administered with the combination of both strains were highly induced compared to those in mice immunized with each strain alone. These results indicated that PapA and PapG worked together for inducing high immune responses. To partly discern the nature of immunity induced by the strains, we quantified serum IgG subtypes IgG1 and IgG2a specific to antigens. The PapA and PapG strains biased the immunity to the Th1-type, as determined by the IgG2a/IgG1 ratio. On the other hand, the immunization with the both strains in combination produced mixed Th1- and Th2-type immune responses. These indicated that immunization with the combination of PapA and PapG could elicit both humoral and cell-mediated immunities.