Date on Senior Honors Thesis


Document Type

Senior Honors Thesis

Degree Name




Degree Program

College of Arts and Sciences

Author's Keywords

biofilms; cystic fibrosis; co-culture


Cystic fibrosis (CF) is an inherited disorder that affects over 30,000 people in the US and more than 70,000 people worldwide. Recurring bacterial infections in CF patients result in tissue damage that dramatically lowers respiratory function and are ultimately fatal. The formation of bacterial biofilms in the mucus and on lung epithelial tissue allows pathogens to be protected from antibiotics and the host immune system, making treatment of infection difficult. The interactions between CF pathogens in co-culture biofilms are not well understood and were examined in this study. Staphylococcus aureus and Burkholderia cenocepacia, two common CF pathogens, were used to examine the effects of co-culture on biofilm formation. We found that S. aureus biofilm formation and maintenance is inhibited when grown in co-culture with B. cenocepacia. In fact, supernatant from 3-day-old biofilms of B. cenocepacia was sufficient to reduce S. aureus biofilms, suggesting that a secreted compound may be responsible for this antagonism. The results of this study can be used to better understand the complex microenvironments bacteria experience in CF lungs. Further exploration of this interaction could lead to discovery of a novel therapeutic or a target for treatment of persistent S. aureus infection.

Lay Summary

Cystic fibrosis is an inherited disease that causes a build up of mucus in the lungs, which leads to deterioration in lung function that is often fatal. Two pathogens, Burkholderia cenocepacia and Staphylococcus aureus, commonly infect the lungs of people with this disease. These bacteria can form biofilms, which are clusters of bacteria surrounded by a sticky matrix, which protects the pathogens from the immune system and from antibiotics. We have found that B. cenocepacia secretes a substance that reduces S. aureus biofilms. This finding could be used in future research for development of new medicine to help treat S. aureus infections.