Genome sequencing of two chronic wound isolated pseudomonas aeruginosa strains to understand adaptation and antibiotic resistance

Pseudomonas aeruginosa is capable of infecting numerous hosts, inhabiting various ecosystems, and tolerating a wide spectrum of environments. Numerous P. aeruginosa strains have been fully sequenced and annotated with comparative genomics providing the opportunity to address why this bacteria is so successful at colonizing different niches. Examining the genetic complexity of P.aeruginosa strains isolated from chronic wounds will further the understanding of how this bacteria adapts to the chronic wound environment and is able to withstand antibiotic treatment. Two P.aeruginosa strains (PA1922 and PA0312), isolated from patients receiving treatment for chronic wounds, were screened for antibiotic susceptibility and shotgun sequenced to characterize genetic content. The susceptibility profiles showed that both PA1922 and PA0312 were resistant to fluoroquinolones and beta-lactams antibiotics. Comparing these wound isolated strains to other Pseudomonas spp., unique genomic regions were identified. Metal resistance operons and antibiotic resistance determinants were found within these predicted genomic islands. A substitution identified in DNA gyrase specifically in subunit A Site 83 (Thr->Ile) was found which relates to fluoroquinolone resistance. PA1922 and PA0312 also have the exotoxin gene exoU which has been identified in highly virulent Pseudomonas strains. The combination of these antibiotic resistance and virulence factors along with the unique genomic regions enable PA1922 and PA0312 to adapt to the wound bed ecology. These multi-factorial determinants complicate treatment options as traditional antibiotic choices are no longer relevant. Understanding the complexity of the Pseudomonas aeruginosa genome and the mechanistic causes of antibiotic resistance and virulence within chronic wounds is critical.