Regional Spread of bla(NDM-1)-Containing Klebsiella pneumoniae ST147 in Post-Acute Care Facilities

Background. Carbapenem-resistant Enterobacterales (CRE) harboring bla(KPC) have been endemic in Chicago-area healthcare networks for more than a decade. During 2016-2019, a series of regional point-prevalence surveys identified increasing prevalence of bla(NDM)-containing CRE in multiple long-term acute care hospitals (LTACHs) and ventilator-capable skilled nursing facilities (vSNFs). We performed a genomic epidemiology investigation of bla(NDM)-producing CRE to understand their regional emergence and spread. Methods. We performed whole-genome sequencing on New Delhi metallo-beta-lactamase (NDM)+ CRE isolates from 4 point-prevalence surveys across 35 facilities (LTACHs, vSNFs, and acute care hospital medical intensive care units) in the Chicago area and investigated the genomic relatedness and transmission dynamics of these isolates over time. Results. Genomic analyses revealed that the rise of NDM+ CRE was due to the clonal dissemination of an sequence type (ST) 147 Klebsiella pneumoniae strain harboring bla(NDM-1) on an IncF plasmid. Dated phylogenetic reconstructions indicated that ST147 was introduced into the region around 2013 and likely acquired NDM around 2015. Analyzing the relatedness of strains within and between facilities supported initial increases in prevalence due to intrafacility transmission in certain vSNFs, with evidence of subsequent interfacility spread among LTACHs and vSNFs connected by patient transfer. Conclusions. We identified a regional outbreak of bla(NDM-1) ST147 that began in and disseminated across Chicago area post-acute care facilities. Our findings highlight the importance of performing genomic surveillance at post-acute care facilities to identify emerging threats.