論文

国際誌
2021年

Genetic Characterization of CTX-M-2-Producing Klebsiella pneumoniae and Klebsiella oxytoca Associated With Bovine Mastitis in Japan.

Frontiers in veterinary science
  • Takeshi Tsuka
  • ,
  • Hiroichi Ozaki
  • ,
  • Daisuke Saito
  • ,
  • Toshiyuki Murase
  • ,
  • Yoshiharu Okamoto
  • ,
  • Kazuo Azuma
  • ,
  • Tomohiro Osaki
  • ,
  • Norihiko Ito
  • ,
  • Yusuke Murahata
  • ,
  • Tomohiro Imagawa

8
開始ページ
659222
終了ページ
659222
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.3389/fvets.2021.659222

CTX-M-2-producing Klebsiella oxytoca (K. oxytoca) has not received much attention in animal husbandry compared with Klebsiella pneumoniae (K. pneumoniae), a major reservoir of extended-spectrum β-lactamase (ESBL) genes. Bacteriological examinations of 1,466 mastitic milk samples between October 2012 and December 2014 were conducted. Ninety-five K. pneumoniae isolates (total prevalence: 6.5%) and 81 K. oxytoca isolates (total prevalence: 5.5%) were obtained. Seventeen K. pneumoniae isolates obtained from 15 animals reared on 11 farms and 9 K. oxytoca isolates obtained from 9 animals reared on the same farm were phenotypically confirmed to be ESBL producers. All nine ESBL-producing K. oxytoca isolates were obtained from one farm between June and November 2013 and related to a significantly (p < 0.05) higher monthly prevalence of mild mastitis (in June, August, September, October, and November 2013). Pulsed-field gel electrophoresis (PFGE) patterns of ESBL-producing K. pneumoniae isolates were distinguished from each other by more than 6-band differences except for two isolates from two animals, whereas all nine K. oxytoca isolates showed an identical PFGE pattern. Transferability of the bla CTX-M-2 gene was found in 14 K. pneumoniae and 9 K. oxytoca isolates by conjugation analysis. Of these isolates, the bla CTX-M-2 gene was detected on plasmids belonging to the incompatibility (Inc) groups P and N derived from five K. pneumoniae and nine K. oxytoca isolates, respectively, although the plasmids from the remaining nine K. pneumoniae were untypeable. All the transconjugants exhibited elevated minimum inhibitory concentrations of ampicillin, cefotaxime, and ceftiofur compared with those in the wild-type, recipient strain. Restriction fragment length polymorphism analysis demonstrated that the IncN plasmids extracted from eight of nine transconjugants, which received resistance against β-lactams from K. oxytoca, showed an identical DraI digestion pattern. These results suggest that the CTX-M-2-producing K. oxytoca strain with the above-mentioned characteristics may have clonally spread within a farm, whereas the bla CTX-M-2 gene in K. pneumoniae possibly disseminated among the farms through different plasmids. Thus, monitoring of ESBL genes, including the bla CTX-M-2 gene, among causative agents of bacterial mastitis in cows can help to develop relevant treatments and control practices.

リンク情報
DOI
https://doi.org/10.3389/fvets.2021.659222
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/34026894
PubMed Central
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8137899
ID情報
  • DOI : 10.3389/fvets.2021.659222
  • PubMed ID : 34026894
  • PubMed Central 記事ID : PMC8137899

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