Genomic characterisation of the first case of IMP-13-producing carbapenem-resistant Pseudomonas aeruginosa ST313/ExoU+/O1 isolate in Chile.

OBJECTIVE

Carbapenemase-resistant Pseudomonas aeruginosa (CR-PA) is a WHO priority pathogen posing a serious public health threat. This study reports the first IMP-13-producing P. aeruginosa isolate (150UDEC/24) in Chile, recovered from a bone infection in April 2024.

METHODS

Antimicrobial susceptibility was determined using disk diffusion and MIC strip tests. Whole-genome sequencing (WGS) was performed on the Illumina NovaSeq platform, and annotation by the NCBI PGAP. Analyses included Staramr, VFDB, MLST, PAst, MOB-Typer, MOB-Recon, and Integron Finder2. Phylogenetic analysis of 150UDEC/24 and 44 ST313 genomes was carried out by IQTree and iTOL for visualization.

RESULTS

The 150UDEC/24 isolate exhibited resistance to relevant antibiotics, including cephalosporins and carbapenems (imipenem, meropenem). It belonged to sequence type (ST) ST313 and serotype O1 and harboured multiple resistance genes: aph(6)-Id, aph(3'')-Ib, aph(3')-IIb, aac(6')-Ib4, aph(3')-VI, catB7, dfrB3, sul1, fosA, blaOXA-488, blaOXA-2, blaPDC-37, and blaIMP-13. The blaIMP-13 gene was embedded in a class 1 integron alongside dfrB3, aac(6')-Ib4, and blaOXA-2. Additionally, the virulence gene exoU was detected. Phylogenetic analysis showed 150UDEC/24 diverged from other ST313 strains, with no other isolate carrying blaIMP-13, suggesting distinct evolution.

CONCLUSIONS

This study provides the first genomic characterization of an IMP-13-producing ST313 carbapenem-resistant P. aeruginosa isolate (150UDEC/24) in Chile, containing multiple resistance genes and the ExoU virulence factor. Phylogenetic analysis suggests unique evolution, emphasizing the need for continued genomic surveillance to monitor the emergence of highly resistant, virulent strains in clinical settings.