Comprehensive Genomic Analysis of Pseudomonas aeruginosa PSU9449 Isolated from a Clinical Case in Thailand

Background/Objectives: Pseudomonas aeruginosa is one of the most significant multidrug-resistant bacteria. It poses considerable challenges in terms of treatment and causes hospital-acquired infections that lead to high morbidity and mortality. Colonization by P. aeruginosa in a patient without clinical signs of infection is a concern in hospital settings, as it is an opportunistic pathogen and can potentially be a multidrug-resistant strain. The objective of this study was to characterize and provide a detailed genomic analysis of this strain of the P. aeruginosa PSU9449 genome, an isolate obtained from a patient at Songklanagarind Hospital, Thailand. Methods: Whole-genome sequencing (WGS) and bioinformatics analysis were employed to examine the genomic features of P. aeruginosa PSU9449. We performed sequence type (ST) determination through multilocus sequence typing (MLST), identified antimicrobial resistance genes (ARGs), virulence factor genes (VFGs), and analyzed the presence of mobile genetic elements (MGEs). Additionally, we compared the PSU9449 genome with strains from neighboring countries to understand its phylogenetic relationship. Results: The P. aeruginosa PSU9449 genome contained five insertion sequences and several ARGs, including fosA, aph (3’)-IIb, blaOXA-50, and catB7. It also harbored VFGs related to flagella (fli, fle, and flg), the type 6 secretion system (hcpA, tssA, and las), and the type 3 secretion system (exoS, exoU, and exoT). MLST identified PSU9449 as ST3777, which was reported in Thailand for the first time. Phylogenetic analysis based on core gene SNPs revealed that PSU9449 was closely related to P. aeruginosa HW001G from Malaysia and P. aeruginosa MyJU45 from Myanmar, forming a distinct clade. Conclusions: This study presents a comprehensive genomic analysis of P. aeruginosa PSU9449, shedding light on its genetic characteristics, antimicrobial resistance profile, and virulence potential. Interestingly, ST3777, the novel STs from the published genomes of P. aeruginosa in Thailand, were assigned in this study. The findings enhance valuable insights into the expanding knowledge of P. aeruginosa PSU9449 and highlight the importance of ongoing surveillance of its genetic diversity.