Outpatient clonal propagation propelled rapid regional establishment of an emergent carbapenem-resistant Acinetobacter baumannii lineage ST499Pas

Academic Article


  • AbstractCombating the evolving health threat posed by carbapenem-resistant Acinetobacter baumannii (CRAb) requires knowing how this non-commensal organism establishes regional pools and propagates among at-risk hosts. We report a 2017-2019 surge of CRAb among patients receiving care in a USA multicenter system. This surge occurred during a period of sustained reduction in hospital-acquired CRAb infections and coincided with marked reduction of CRAb cases associated with distinctly more resistant antibiotypes. Isolate whole genome sequencing revealed surge isolates belonged to an emergent Pasteur scheme sequence type 499 (ST499Pas). Detailed query of health records guided by isolate genome comparative analyses revealed multiple clonal clusters linked to various outpatient healthcare settings (i.e., long term healthcare facilities, surgical and wound clinics, and other unidentified factors) but no evidence of a shared intrahospital source. We show that emergent CRAb lineages can rapidly establish a regional presence even without gains in breadth of antibiotic resistance and negligible contribution from sustained intrahospital transmission. The emergence of ST499Pas despite regional eradication of other CRAb lineages shows how control efforts could be sidestepped via outpatient epidemiological niches. We also establish an approach to investigate the propagation of CRAb lineages that can inform subsequent local surveillance efforts outside of hospital settings.
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  • Calix JJ; Stockler de Almeida MC; Potter RF; Wallace MA; Burnham C-AD; Dantas G