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The First Case of Community-Acquired Pneumonia Due to Capsular Genotype K2-ST86 Hypervirulent Klebsiella pneumoniae in Okinawa, Japan: A Case Report and Literature Review

Authors Hirai J, Sakanashi D, Kinjo T, Haranaga S, Fujita J

Received 15 March 2020

Accepted for publication 24 June 2020

Published 10 July 2020 Volume 2020:13 Pages 2237—2243


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Sahil Khanna

Jun Hirai,1 Daisuke Sakanashi,2 Takeshi Kinjo,1 Shusaku Haranaga,3 Jiro Fujita2

1Department of Infectious, Respiratory and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan; 2Department of Infection Control and Prevention, Aichi Medical University Hospital, Aichi 480-1195, Japan; 3Comprehensive Health Professions Education Center, University of the Ryukyus Hospital, Okinawa 903-0215, Japan

Correspondence: Jun Hirai Email

Abstract: Hypervirulent Klebsiella pneumoniae (HV-KP) typically causes pyogenic liver abscess and bacteremia with metastatic infections. Community-acquired pneumonia (CAP) due to HV-KP is uncommon and details of its clinical and microbiological features are limited. We report the first case of CAP due to capsular genotype K2-ST86 HV-KP in Okinawa, Japan and review infections caused by the K2-ST86 strain. A 79-year-old woman presenting with fever and productive cough persisting for the past three days was admitted to hospital. Her vital signs indicated septic shock. Lung examination by auscultation revealed holo-crackle and lobar pneumonia in chest radiography, and Streptococcus pneumoniae was suspected. However, sputum and blood cultures revealed Gram-negative coccus identified as K. pneumoniae. Genetic analysis identified the isolated strain as the K2 serotype harboring rmpA, iutA, entB, and mrkD. Therefore, we identified the isolated strain as hypervirulent. The isolate belonged to ST86 as determined by multilocus sequence typing. The case was not complicated by predisposing factors such as diabetes mellitus and malignancy related to HV-KP infection; thus, this CAP-causing HV-KP strain may differ from the typical HV-KP strain that induces liver abscess. A literature review identified only nine cases with CAP due to HV-KP. In all cases, the disease mainly occurred in older males with diabetes mellitus, which makes the present case unusual, and had high rates of septic shock and death. No case, including ours, was complicated by metastatic infection, suggesting that CAP due to HV-KP poses little distant metastasis risk, even in patients with bloodstream infection. In our review, consistent with our case, K2-ST86 was the most common strain of HV-KP in patients with CAP. Therefore, studies are needed to elucidate the clinical and microbiological features of HV-KP CAP, with a focus on the K2-ST86 strain. Physicians should always consider K. pneumoniae in cases of sepsis CAP with lobar pneumonia.

Keywords: hypervirulent Klebsiella pneumoniae, community-acquired pneumonia, serotype K2, sequence type 86, lobar pneumonia, Streptococcus pneumoniae

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