Genomic Characterization of Extremely Antibiotic-Resistant Strains of Pseudomonas aeruginosa Isolated from Patients of a Clinic in Sincelejo, Colombia.

Pseudomonas aeruginosa is an opportunistic pathogen classified as a priority and a great public health concern; therefore, this research focuses on the genomic characterization of extremely resistant strains of P. aeruginosa isolated from patients in a clinic in Sincelejo, Colombia. Seven strains were analyzed by whole genome sequencing using the Illumina NovaSeq platform, with a focus on the identification of resistance genes and virulence factors through the CARD and VFDB databases. An ANI (Average Nucleotide Identity) analysis was carried out to determine the genetic relationship between the strains, complemented by a phylogenomic analysis to place the strains in different evolutionary clades. The results revealed that six of the strains are of Colombian origin, while one strain (547256) belongs to the high-risk clone ST773, previously unidentified in Colombia. Genome size ranged from 6 to 7.4 Mbp, indicating differences in genetic content among strains. Phylogenomic analysis confirmed that five strains belong to a multidrug-resistant (MDR) group, while one strain (572897) showed high alignment with a laboratory strain, and strain 547256 was not associated with any specific clade. Clinically, 100% of strains showed carbapenem resistance, resistance genes, and virulence factors that make them difficult to treat. This study provides key insights into the genetic diversity and resistance patterns of P. aeruginosa in this region, underscoring the need to monitor high-risk clones and optimize therapeutic strategies.