ABSTRACT
Background
Carbapenem-resistant
Klebsiella pneumoniae (CR
Kp) is the most prevalent carbapenem-resistant Enterobacterales in the United States. We evaluated clustering of CR
Kp in hospitalized patients in US hospitals.
Methods
From April 2016 to August 2017, 350 patients with clonal group 258 were included as part of the Consortium on Re sistance Against Carbapenems in
Klebsiella and other
Enterobacteriaceae (CRACKLE-2), a prospective, multicenter, cohort study. A maximum-likelihood tree was constructed using RAxML. Static clusters shared ≤21 single nucleotide polymorphisms (SNP) and a most recent common ancestor. Dynamic clusters incorporated SNP distance, culture timing, and rates of SNP accumulation and transmission using the R program TransCluster.
Results
Most patients were admitted from home (n = 150, 43%) or a long-term care facility (n = 115, 33%). Urine (n = 149, 43%) was the most common site of isolation. In total, 55 static and 47 dynamics clusters were identified involving 210/350 (60%) and 194/350 (55%) patients, respectively. About half of static clusters were identical to dynamic clusters. Static clusters consisted of 33 (60%) intra-system and 22 (40%) inter-system clusters. Dynamic clusters consiste d of 32 (68%) intra-system and 15 (32%) inter-system clusters and had fewer SNP differences compared to static clusters (8 versus 9, P= 0.045, 95% CI: [-4, 0]). Dynamic inter-system clusters contained more patients than dynamic intra-system clusters (median [IQR]: 4 [2, 7] vs 2 [2, 2], P= 0.007, 95% CI: [-3, 0]).
Conclusions
Widespread intra-system and inter-system transmission of CR
Kp was identified in hospitalized US patients. Employing different methods for assessing genetic similarity resulted in only minor differences in interpretation.
