Objectives/Goals: The goal of this study is to explore the lysogenized bacteriophages of clinical isolates of Pseudomonas aeruginosa (Pa) for their capacity to affect intraspecies competition. This study also aims to explore the capacity of using clinical isolates as a source of new candidates for phage therapy. Methods/Study Population: We compiled a collection of 207 Pa isolates and screened them for the presence of lysogenic phages using polymerase chain reaction (PCR). A subset of 96 phage containing clinical isolates was tested for intra-strain infectivity. Using a representative subset of isolates producing infective and non-infective phage, we evaluated competitive dynamics in liquid co-cultures, bacterial biofilms and in a murine chronic wound model. Results/Anticipated Results: Among all isolates, 74.3% contained detectable phages in their genome, and 63.7% contained detectable phage in their supernatants. Among those tested for intra-strain infectivity, 82.2% of strains demonstrated inhibition of growth on lawns of at least one other strain, while 94.8% of these strains were susceptible to at least one other supernatant. In in vitro co-culture competition experiments, strains producing infective phages outcompeted competitors more effectively than strains producing non-infective phage. Infective phage producing strains were more resistant to biofilm invasion than non-infective counterparts. In vivo competition experiments showed that PAO1 was significantly reduced when co-infecting with an infective phage-producing strain compared to a non-infective one. Discussion/Significance of Impact: Collectively, these data demonstrate that clinical isolates of Pa frequently encode active bacteriophages that can mediate intraspecies competition and confer a competitive advantage during infection. Future work will center on combining these phages as therapeutic cocktails targeting acute Pa infections.
Prokopczuk et al. (Wed,) studied this question.