Molecular characteristics of extended-spectrum β-lactamase-producing Klebsiella pneumoniae in Japan: Predominance of CTX-M-15 and emergence of hypervirulent clones

Naoki Kakuta, Ryuichi Nakano, Akiyo Nakano, Yuki Suzuki, Takashi Masui, Saori Horiuchi, Risako Kakuta, Kohsuke Tsubaki, Miho Ogawa, Hisakazu Yano

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    5 Citations (Scopus)

    Abstract

    Objective: To provide data on the molecular characteristics of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae clinical isolates in Japan. Methods: A total of 100 clinical isolates of ESBL-producing K. pneumoniae collected throughout Japan between June and July 2018 were studied. ESBL genes were analyzed using PCR and DNA sequencing. Transferability of ESBL genes was investigated by conjugation experiments. Plasmid replicon types, virulence genes (rmpA, rmpA2, iucA, iroB, and peg-344) associated with hypervirulent K. pneumoniae (hvKp), and capsule types were detected using PCR. Genotyping was performed using multilocus sequence typing. Results: All ESBL-producing isolates carried blaCTX-M genes. The most predominant CTX-M-type identified was CTX-M-15 (n = 55). We identified 24 sequence types (STs) among the CTX-M-15 producers, with ST25 (n = 8) being the most common. Most of the transconjugants carrying blaCTX-M-15 contained the FIIk replicon. Of the 100 ESBL-producing isolates, 31 were hvKp defined by the presence of the virulence genes. These ESBL-producing hvKp isolates belonged to eight STs (STs 23, 25, 36, 65, 86, 268, 412, and 4492), with five capsule types (K1, K2, K20, K57, and undefined). Conclusions: CTX-M-15 was the predominant ESBL among K. pneumoniae isolates from Japan. This study shows that ESBL-producing hvKp strains comprising various clones are emerging in Japan.

    Original languageEnglish
    Pages (from-to)281-286
    Number of pages6
    JournalInternational Journal of Infectious Diseases
    Volume98
    DOIs
    Publication statusPublished - 2020 Sep

    Keywords

    • CTX-M-15
    • Extended-spectrum β-lactamase
    • Hypervirulent
    • Klebsiella pneumoniae

    ASJC Scopus subject areas

    • Microbiology (medical)
    • Infectious Diseases

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