Genomic diversity and antibiotic resistance determinants of Pseudomonas aeruginosa associated with war-wound infections in Ukraine.

INTRODUCTION

This study continues the surveillance of antimicrobial resistance and genetic determinants of hypervirulence in Pseudomonas aeruginosa associated with combat injuries in Ukraine.

AIM: The aim of the study is to characterise the antibiotic resistance patterns and prevalence of high-risk international lineages of P. aeruginosa isolated from infected wounds in Ukraine during the war in 2022-2023.

METHODS

Forty P. aeruginosa isolates were obtained from wound swabs of 171 injured soldiers treated at three military hospitals in central Ukraine. Bacterial identification and antibiotic susceptibility testing (AST) were conducted using disk diffusion (EUCAST) and broth microdilution. Whole-genome sequencing (WGS) and genomic analyses were performed at the Walter Reed Army Institute of Research to better characterise the isolates.

FINDINGS: Isolates of P. aeruginosa exhibited highly resistant profiles, with 60% classified as extensively drug-resistant (XDR) and 15% as multi-drug-resistant (MDR). High resistance to fluoroquinolones and imipenem was observed, though all isolates were susceptible to colistin. Ten sequence types were identified, with high-risk clones ST773 (32.5%) and ST1047 (25.0%) being the most common, followed by ST389 (10.0%) and ST235 (7.5%). Genotypic analysis showed prevalent carbapenemases, blaNDM-1 (ST773) and blaIMP-1 (ST1047), frequently co-occurring with 16S rRNA methylase rmtB4. High-risk lineages (ST773, ST1047, ST235, and ST357) harboured the exoU cytotoxin gene, whereas ST389 carried exoS.

CONCLUSION

This study highlights the prevalence of XDR P. aeruginosa driven by the dissemination of international high-risk clones (ST773, ST1047, and ST235). The presence of blaNDM-1 and blaIMP-1 carbapenemases, combined with the exoU virulence marker, poses a severe challenge to clinical management. Genetically related clusters across different hospitals suggest inter-hospital transmission.