Tracing the origins of multidrug resistant bacteria in Ukraine

Background A key medical characteristic of the current conflict in Ukraine has been the extraordinary number of wounds being infected by multidrug resistant organisms (MDROs). The origin and spread of these organisms have been the subject of intense interest and debate, yet the reservoirs and transmission routes remain poorly defined. In this study, environmental sampling was performed across the Ukrainian medical evacuation chain to better understand transmission dynamics. Methods 127 environmental swabs were collected from environmental surfaces in three frontline hospitals ( n = 17 swabs), two evacuation assets (12 swabs), a large regional healthcare facility that provides full clinical and surgical capabilities (23 swabs), and three definitive care and rehabilitative hospitals (75 swabs). Swabs were incubated in Brain Heart Infusion broth and then cultured on non-selective and selective agars. Short- and long-read sequencing were performed using an Illumina NextSeq 2000 and MinION, respectively. The resulting genomes were compared to a collection of clinical bacteria cultured from patients in healthcare facilities in Denmark, Germany, The Netherlands, and Ukraine. Results Bacterial growth was recorded from 112 swabs (88%) and 280 distinct environmental strains, representing 89 bacterial species, were cultured. Notably, MDROs were effectively absent from the frontline facilitates and evacuation assets but were detected in 48–56% of environmental samples from rear-echelon hospitals. Genomic analysis revealed that these rear-echelon hospital environments were dominated by epidemic lineages of Acinetobacter baumannii , Pseudomonas aeruginosa , and Klebsiella pneumoniae that frequently carried carbapenemases. A genetic comparison of the environmental bacteria with clinical strains cultured from injured soldiers and refugees receiving care in hospitals in Ukraine, Denmark, Germany, and The Netherlands revealed high levels of genetic relatedness. Compounding the problem, plasmidome analysis identified horizontal dissemination of resistance genes across species within the hospital environment. Conclusions These findings implicate hospital environments as key reservoirs and amplifiers of MDROs during conflict, highlighting their central role in sustaining local transmission and international spread.