Controlling Staphylococcus aureus by 2-[(Methylamino)methyl]phenol (2-MAMP) in a co-culture moderates the biofilm and virulence of Pseudomonas aeruginosa

Staphylococcus aureus and Pseudomonas aeruginosa are the most encountered organisms in a polymicrobial chronic wound infection. Production of multiple virulence factors by this duo delays wound healing process. Notably P. aeruginosa displays enhanced virulence in the presence of S. aureus by a peptidoglycan sensing mechanism. Thus novel therapies are imperative to address polymicrobial infections effectively. Previously, it has been suggested that targeting S. aureus might be a possible approach to reduce the severity of P. aeruginosa in a polymicrobial infection. In this aspect, we have used 2-[(Methylamino)methyl]phenol (2-MAMP), our previously reported QS inhibitor to target S. aureus and phenotypically determine the virulence factors of P. aeruginosa under this condition. Analysis of major virulence factors of Pseudomonas viz. biofilm, pyocyanin and pyoveridine showed a significant reduction. The competitive index (CI) and relative increase ratio (RIR) were determined to understand the organisms interaction in co-culture. Results indicated competitiveness among the strains and on increasing ratios of S. aureus cells, co-existence was noticed. Further as a sensible approach antibiotic anti-virulence drug combinations were tested on co-culture. Significant improvement in the growth inhibition was observed. Our preliminary results presented here would enable further research to address polymicrobial infection in a novel way.

The evolution of virulence in Pseudomonas aeruginosa during chronic wound infection

Opportunistic pathogens are associated with a number of chronic human infections, yet the evolution of virulence in these organisms during chronic infection remains poorly understood. Here, we tested the evolution of virulence in the human opportunistic pathogen Pseudomonas aeruginosa in a murine chronic wound model using a two-part serial passage and sepsis experiment, and found that virulence evolved in different directions in each line of evolution. We also assessed P. aeruginosa adaptation to a chronic wound after 42 days of evolution and found that morphological diversity in our evolved populations was limited compared with that previously described in cystic fibrosis (CF) infections. Using whole-genome sequencing, we found that genes previously implicated in P. aeruginosa pathogenesis ( lasR , pilR , fleQ , rpoN and pvcA ) contained mutations during the course of evolution in wounds, with selection occurring in parallel across all lines of evolution. Our findings highlight that: (i) P. aeruginosa heterogeneity may be less extensive in chronic wounds than in CF lungs; (ii) genes involved in P. aeruginosa pathogenesis acquire mutations during chronic wound infection; (iii) similar genetic adaptations are employed by P. aeruginosa across multiple infection environments; and (iv) current models of virulence may not adequately explain the diverging evolutionary trajectories observed in an opportunistic pathogen during chronic wound infection.

The evolution of virulence in Pseudomonas aeruginosa during chronic wound infection

ABSTRACTOpportunistic pathogens are associated with a number of chronic human infections, yet the evolution of virulence in these organisms during chronic infection remains poorly understood. Here, we tested the evolution of virulence in the human opportunistic pathogen Pseudomonas aeruginosa in a murine chronic wound model using a two-part serial passage and sepsis experiment, and found that virulence evolved in different directions in each line of evolution. We also assessed P. aeruginosa adaptation to a chronic wound after 42 days of evolution, and found that morphological diversity in our evolved populations was limited compared to that previously described in cystic fibrosis (CF) infections. Using whole genome sequencing, we found that genes previously implicated in P. aeruginosa pathogenesis (lasR, pilR, fleQ, rpoN, and pvcA), acquired mutations during the course of evolution in wounds, with some mutations evolving in parallel across all lines of evolution. Our findings highlight that (i) P. aeruginosa heterogeneity may be less extensive in chronic wounds than in CF lungs; (ii) genes involved in P. aeruginosa pathogenesis acquire mutations during chronic wound infection; (iii) similar genetic adaptations are employed by P. aeruginosa across multiple infection environments, and (iv) current models of virulence may not adequately explain the diverging evolutionary trajectories observed in an opportunistic pathogen during chronic wound infection.