I am currently examining the interaction between populations of Pseudomonas aeruginosa and Staphylococcus aureus, two of the most common pathogens infecting the cystic fibrosis (CF) patients. This project is in collaboration with Waqas Chaudry  and Bruce Levin in our Lab (the EcLF), and Joanna Goldberg and her Postdoc Eryn Bernardy, and graduate student Ashley Alexander.

Although these bacteria regularly co-infect the lungs of CF patients, in vitro, P. aeruginosa inhibits the replication of and kills S. aureus.   Although a great deal about the interactions between these bacteria at the molecular level, there remain major unanswered questions about the population dynamics, ecology and evolution of this antagonistic relationship between these Gram-negative and Gram-positive bacteria:  (i) How do they co-exist in the lungs of CF patients? (ii) What are the selective pressures responsible for evolution and maintenance of mechanisms for P. aeruginosa to inhibit the growth and kill S. aureus.   (iii)  Why don’t S. aureus evolve mechanisms to evade the inhibition of growth and killing by P. aeruginosa?   Using mathematical models and in vitro population dynamic and evolutionary experiments I am addressing and providing answers to these questions.

For more information about this project, please write to me at ross.greenberg@emory.edu