Role of R5 pyocin in the predominance of high-risk Pseudomonas aeruginosa isolates

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Antimicrobial resistance is a major healthcare challenge.
• Pseudomonas aeruginosa, particularly multidrug-resistant strains like ST235 and ST111, frequently causes infections in healthcare settings.
• The reasons for the dominance of specific P. aeruginosa sequence types (STs) are not fully understood.

Purpose of the Study:

• To investigate the genetic basis for the clinical dominance of specific Pseudomonas aeruginosa sequence types.
• To identify factors contributing to the competitive advantage of high-risk P. aeruginosa strains.

Main Methods:

• Genome-wide transposon-insertion library screening was employed to identify genes conferring a competitive advantage.
• Mutagenesis studies were performed by deleting R5 pyocin genes in ST111 and ST235 strains.
• Analysis of a large collection of 5135 P. aeruginosa strains was conducted.

Main Results:

• Production of R5 pyocins was found to confer a significant competitive advantage to ST111 P. aeruginosa strains.
• Mutants lacking R5 pyocin production lost their competitive dominance.
• Several international high-risk P. aeruginosa sequence types, including ST235 and ST111, showed enrichment for R5 pyocin production.
• Deletion of an R5 pyocin structural gene in an ST235 strain resulted in loss of competitive advantage.

Conclusions:

• R5 pyocin production is a key factor contributing to the clinical dominance of specific high-risk Pseudomonas aeruginosa sequence types.
• This finding suggests a potential mechanism for evaluating the risk posed by emerging P. aeruginosa strains.
• Understanding these mechanisms is crucial for combating antimicrobial resistance in clinical settings.