C-reactive protein levels in acute respiratory exacerbations of cystic fibrosis.

C-reactive protein (CRP) levels increase in response to bacterial infection and have been used to guide the use of antibiotics. We assessed CRP levels in a cohort of patients with cystic fibrosis (CF) admitted to hospital with an exacerbation of their lung disease, requiring treatment with broad-spectrum antibiotics. In this group, most subjects had CRP levels of less than 20 mg/L, including patients who had pneumonia. The clinical utility of the CRP in guiding antibiotic use in exacerbations of CF is limited.