Authors
Shogo Saito, Satoko Nakashima, Kentaro Endo, Kazuya Narita, Yuji Hatakeyama, Yuji Suzuki, Ryuichi Nakano, Yuki Suzuki, Hisakazu Yano, Tohru Fujiwara, Kiwamu Nakamura
Published in
Japanese journal of infectious diseases. Jun 30, 2026. Epub Jun 30, 2026.
Abstract
Klebsiella quasipneumoniae is a member of the Klebsiella pneumoniae complex that is difficult to distinguish from K. pneumoniae using conventional laboratory methods, and information on its clinical manifestations is limited. We describe the first known case of invasive infection with hypervirulent K. quasipneumoniae subsp. similipneumoniae in Japan. A 65-year-old woman with pancreatogenic diabetes mellitus presented with fever and nausea. Computed tomography revealed a liver abscess and multiple pulmonary nodules with cavitation suggestive of septic pulmonary emboli. Blood cultures yielded an isolate identified as K. pneumoniae complex. Whole-genome sequencing (WGS) subsequently identified the isolate as K. quasipneumoniae subsp. similipneumoniae, sequence type 367 (ST367) and capsular type K1 (KL1). The isolate exhibited a hypermucoviscous phenotype and harbored the virulence-associated genes iroBCDN, iucABCD/iutA, rmpA/A2, and peg-344. The patient improved following antimicrobial therapy with meropenem for 10 days, followed by cefmetazole for 13 days, and was discharged home after a hospital stay of 81 days. This case highlights the potential for invasive infection caused by hypervirulent K. quasipneumoniae, the usefulness of WGS for species identification, and the need for ongoing clinical and genomic surveillance to monitor the emergence of this pathogen.
PMID:
42386601
Bibliographic data and abstract were imported from PubMed on 02 Jul 2026.
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