Infection with capsular genotype K1-ST23 hypervirulent Klebsiella pneumoniae isolates in Japan after a stay in East Asia: Two cases and a literature review

Disseminated community-acquired infections caused by the hypervirulent Klebsiella pneumoniae (hvKp) among relatively healthy individuals in East Asia have been reported in recent years. Isolate of the capsular genotype K1, belonging to sequence type (ST) 23, is the most common causative agent of this disease. We experienced two cases of K1-ST23 infection with a travel history in East Asia, and hvKp infection was diagnosed after entering or returning to Japan. Case 1 was a 45-year-old Myanmar seaman with a history of ischemic heart disease who developed a fever on board and was transported to Japan via Shanghai and Taiwan. He had multiple disseminated lesions due to K. pneumoniae; other symptoms included liver abscess, intraocular inflammation, intraventricular thrombosis, brain abscess, and bloodstream infection. Along with antimicrobial treatment, drainage of liver abscesses and surgery for intraocular inflammation and intraventricular thrombosis were required. The patient was discharged 93 days after admission, with little improvement in the visual acuity. Case 2: A 29-year-old Japanese man with no underlying disease developed a prostate abscess and bloodstream infection caused by K. pneumoniae after a trip to Korea. However, he improved only with antimicrobial treatment. K. pneumoniae in both cases were identified to have the rmpA gene, with capsular genotypes K1 and ST23. Further, both cases were considered to have been infected with hvKp during their stay in East Asia. In conclusion, it is important to suspect disseminated disease and perform a systemic search, taking into account that hvKp may be present in cases of Klebsiella infection acquired from East Asia.