Investigating the Bacteria That Cause Cystic Fibrosis
Dr. Jane Burns and Research Technician Adam Griffith
Cystic fibrosis (CF) is the most common life-shortening genetic illness in Caucasians, affecting approximately 30,000 children and adults in the U.S. alone. The abnormal CFTR gene impacts many organs, including the lungs, gastrointestinal tract and endocrine system. Chronic lung infections are the most common cause of morbidity and mortality in CF and our work is focused on the bacterial organisms that cause CF lung infections, including Pseudomonas aeruginosa, Burkholderia cepacia complex and Staphylococcus aureus. Because CF lung infections are polymicrobial, our work also addresses bacterial-bacterial interactions.
Burkholderia cepacia complex
P. aeruginosa is the most common organism causing lung infections in CF patients of all ages (although S. aureus is most common in children). The Burns lab's work on P. aeruginosa has primarily centered on early infections and how to eradicate them. Antibiotic resistance among P. aeruginosa isolates, including prevention, detection and treatment, has also been a longstanding area of research.
B. cepacia complex infections are relatively rare among individuals with CF, but can be deadly. Improving our understanding of the pathogenesis of these infections and identifying optimal treatment strategies are key to our ability to decrease the associated morbidity and mortality in CF patients harboring B. cepacia complex.
To evaluate optimum methods for testing small colony variant Staphylococcus aureus, the Burns lab uses the disk diffusion technique to compare susceptibility results for organisms growing in different oxygen conditions on a variety of media.
As noted above, S. aureus is the organism most frequently isolated from children with CF. For many years, S. aureus was considered a "colonizer" that did not cause severe infections. However, recent data from our laboratory and others has identified increased morbidity in children infected with both methicillin resistant S. aureus (MRSA) and small colony variant S. aureus.
The Burns lab's current projects include investigation of the pathogenesis of B. cepacia complex in CF including the role of mucoidy in Burkholderia species and the contribution of hypermutability to specific bacterial phenotypes and clinical outcomes in B. cenocepacia infections in CF. In addition, the prevalence of small colony variant S. aureus and its impact on disease progression in children is being investigated. At the same time, we are developing new methods for antimicrobial susceptibility testing in these slow-growing variants with the goal of ultimately performing a large multicenter clinical trial.