Although anaerobic bacteria exist in abundance in cystic fibrosis (CF) airways, their role in disease progression is poorly understood. We hypothesized that the presence and relative abundance of the most prevalent, live, anaerobic bacteria in sputum
of adults with CF were associated with adverse clinical outcomes. This is the first study to prospectively investigate viable
anaerobic bacteria present in the sputum microbiota and their relationship with long-term outcomes in adults with CF. We performed 16S rRNA analysis using a viability quantitative PCR technique on sputum samples obtained from a prospective cohort
of 70 adults with CF and collected clinical data over an 8year follow-up period. We examined the associations of the ten most
abundant obligate anaerobic bacteria present in the sputum with annual rate of FEV1
change. The presence of Porphyromonas
pasteri and Prevotella nanceiensis were associated with a greater annual rate of FEV1
change; −52.3ml yr−1 (95%CI-87.7;−16.9),
–67.9ml yr−1 (95%CI-115.6;−20.1), respectively. Similarly, the relative abundance of these live organisms were associated with
a greater annual rate of FEV1
decline of −3.7ml yr−1 (95%CI: −6.1 to −1.3, P=0.003) and −5.3ml yr−1 (95%CI: −8.7 to −1.9, P=0.002)
for each log2
increment of abundance, respectively. The presence and relative abundance of certain anaerobes in the sputum of
adults with CF are associated with a greater rate of long-term lung function decline. The pathogenicity of anaerobic bacteria in
the CF airways should be confirmed with further longitudinal prospective studies with a larger cohort of participants.