Klebsiella pneumoniae independently causing necrotizing fasciitis in patients with Klebsiella pneumoniae bacteremia is known and has mainly been reported from East Asia, especially Taiwan and Korea. The clinical course of necrotizing fasciitis developing in association with K. pneumoniae bacteremia has not yet been clearly described. We report a case of lower leg K. pneumoniae necrotizing fasciitis in a patient with following K. pneumoniae bacteremia, which was unrecognized on day 1 of admission. The necrotizing fasciitis, which necessitated surgical treatment, became clinically evident only after the bacteremia diagnosis. A 65- year-old Korean woman who presented with a history of fever and malaise developed septic shock of unknown origin. Although effective antimicrobial therapy was initiated soon after she was admitted to us, purpura and pain in the left lower leg appeared on day 6 of admission, and necrotizing fasciitis was suspected. The patient recovered after surgical treatment and was discharged on day 25 of hospitalization. The isolated K. pneumoniae showed a positive string test, and genetic analysis identified it as the K1-ST23 strain, which is known to be a hypervirulent K. pneumoniae (hvKp) strain. It has been suggested that hvKp bacteremia can cause necrotizing fasciitis even during effective antimicrobial therapy, and because of the need for immediate surgical treatment, clinicians should be very attentive to the appearance of a new skin or soft tissue lesion in patients with K. pneumoniae bacteremia. The index of suspicion should be even higher in patients from East Asia and for K. pneumoniae strains that are string test-positive.
