Decoding Pseudomonas aeruginosa: Genomic insights into adaptation, antibiotic resistance, and the enigmatic role of T6SS in interbacterial dynamics

Abstract

Pseudomonas aeruginosa demonstrates a remarkable capacity for adaptation and survival in diverse environments. Furthermore, its clinical importance is underscored by its intrinsic and acquired resistance to a wide range of antimicrobial agents, posing a substantial challenge in healthcare settings. Amidst this complex landscape of resistance, the Type VI Secretion System (T6SS) in P. aeruginosa adds yet another layer of intricacy and allows bacteria to engage in interbacterial competition, potentially influencing their resilience and pathogenicity. Whole genome sequencing (WGS) was conducted on the five isolates under investigation, enabling the identification of antibiotic resistance genes (ARGs) and mutations associated with resistance. All isolates exhibit class C and D β-lactamases, displaying variant differences. The Resistance-nodulation-division (RND) antibiotic efflux pumps, crucial for multidrug resistance, have been encoded chromosomally. When exploring the role of the T6SS in urinary tract infections involving other bacteria, it was noted that P. aeruginosa isolates exhibited reduced counts when co-cultivated with other bacteria. The downregulation of the tssJ gene, associated with the T6SS under bacterial stress, and the exclusion of several cluster genes in this study suggest the hypothesis of a basal state rather than an attack/defence mechanism in the initial contact.