Microbial Interactions in the Cystic Fibrosis Airway.

Interactions in the airway ecology of cystic fibrosis may alter organism persistence and clinical outcomes. Better understanding of such interactions could guide clinical decisions. We fitted logistic regression models using generalized estimating equations to longitudinal two-year patient cohorts in the Cystic Fibrosis Foundation Patient Registry, 2003-2011 to study associations between airway organisms present in each calendar year and their presence in the subsequent year. Models were adjusted for clinical characteristics and multiple observations per patient and tested for sensitivity to cystic fibrosis-specific treatments. The study included 28,042 patients aged six and older from 257 accredited US Care Centers and Affiliates with sputum cultures for at least two consecutive years for methicillin-sensitive Staphylococcus aureus , methicillin-resistant S aureus, Pseudomonas aeruginosa, Burkholderia cepacia complex, Stenotrophomonas maltophilia, Achromobacter xylosoxidans , and Candida and Aspergillus species. We analyzed 99.8% of 538,458 sputum cultures from the patients during the study period. Methicillin-sensitive S aureus was negatively associated with subsequent P aeruginosa. P aeruginosa was negatively associated with subsequent B cepacia complex, A xylosoxidans , and S maltophilia. B cepacia complex was negatively associated with future presence of all studied bacteria and Aspergillus species. P aeruginosa, B cepacia complex and S maltophilia were each reciprocally and positively associated with Aspergillus species. Independent of patient characteristics, studied organisms interact and alter outcomes of treatment decisions, sometimes in unexpected ways. By inhibiting P aeruginosa , methicillin-sensitive S aureus may delay lung disease progression. P aeruginosa and B cepacia complex may inhibit other organisms by decreasing airway biodiversity, potentially worsening lung disease.