Klebsiella pneumoniae NSSTI is an emergent disease that has been associated with hypervirulent strains (hvKP) and hypermucoviscosity phenotype (hmvKP). Typically, hvKP strains are susceptible to most antibiotics. However, multidrug-resistant hvKP have been recently reported in Asia and Brazil. This study evaluates the presence of virulence factors and hypermucoviscosity in CR-KP strains causing NSSTI.
Retrospective study of CR-KP NSSTI diagnosed at a tertiary US hospital from Jan 2012 to Jan 2016. Demographic, clinical, and antibiotic susceptibility (Vitek) data, were obtained by chart review. Archived isolates from tissue cultures underwent whole genome sequencing (Illumina MiSeq). Sequence data was de novo assembled and searched against a database of antibiotic resistance genes (ResFinder) and virulence genes (rmpA, magA, mrkD, fimH, aerobactin, kfu, entB, ybtS, allS). In silico MLST and capsular typing were also performed. Capsule production was measured by quantification of uronic acid production.
During the study period, 4 cases of CR-KP NSSTI were identified. All patients were immunosuppressed (3/4) or had diabetes mellitus (2/4). All cases received adequate surgical and antibiotic treatment. Although in-hospital mortality was 0%, 2 patients had relapse of infection and 2 patients died after discharge, to yield an overall-mortality of 50% and an infection-attributable mortality of 25%. All of the strains had at least 2 virulence genes previously associated with hvKP strains (mrkD and entB), but all lacked the rmpA gene. One strain was found to be hmvKP by string test (NU-CRE265). This strain belonged to the ST14 clone, K2 capsular type, and carried a KPC-3 gene in addition to other ESBL genes. Capsule production for this hmvKP strain was nearly twice that of other strains.
CR-KP is an emergent cause of NSSTI. These strains carry some virulence genes previously described in susceptible hvKP strains, although their role in the pathogenesis of NSSTI needs to be further studied. This is the first report of a carbapenem resistant hmvKP causing NSSTI, as well as the first report of a hmvKP KPC-3 strain. Larger studies are needed to determine the incidence of CR-KP NSSTI and associated virulence factors in the US.
F. Krapp Lopez,
E. Ozer, None
A. R. Hauser, None