Recent trend of necrotizing fasciitis in Taiwan: focus on monomicrobial Klebsiella pneumoniae necrotizing fasciitis.

BACKGROUND Necrotizing fasciitis (NF) is a rapidly progressive, life-threatening soft-tissue infection that is traditionally caused by group A Streptococcus (GAS) or mixed aerobic/anaerobic bacteria. Monomicrobial Klebsiella pneumoniae NF (KP-NF) has been reported since 1996 but has not yet been systematically studied. METHODS We retrospectively studied consecutive NF cases treated at a university hospital in Taiwan during 1997-2010 and investigated the clinical characteristics and outcomes associated with monomicrobial KP-NF, using monomicrobial GAS-NF as a reference. We also analyzed the virulence gene profiles of the isolated K. pneumoniae strains. RESULTS Of 134 NF cases, 88 were monomicrobial, of which the most common pathogens were GAS (n = 16) and K. pneumoniae (n = 15). Monomicrobial KP-NF entailed a moderate risk of limb loss (20% vs 25%; P = 1.000) and high mortality (47% vs 19%; P = .135), and it was more likely to involve bacteremia (80% vs 31%; P = .011), concomitant distant abscesses (27% vs 0%; P = .043), and underlying immunocompromising conditions (100% vs 63%; P = .018), compared with GAS-NF. The isolated K. pneumoniae strains (n = 10) were of capsular polysaccharides genotype K1 (n = 4), K54/K20/K5 (n = 4), K2 (n = 1), and K16 (n = 1). All strains carried rmpA, iucABCDiutA, and iroA. Genotype K1 strains had a significantly higher risk of concomitant distant abscesses, compared with non-K1 strains (75% vs 0%; P = .033). CONCLUSIONS K. pneumoniae has become a common pathogen of monomicrobial NF in Taiwan. Physicians treating patients with monomicrobial KP-NF should be aware of the risk of concomitant distant abscesses, particularly in cases caused by genotype K1.