Daily change in community structure from baseline into exacerbation. Day-to-day changes in airway bacterial community structure in four persons with CF. Bray-Curtis dissimilarity between consecutive daily samples is shown during periods of clinical stability (blue) that ended with the onset of symptoms of exacerbation (pink). Dashed lines indicate more than one day between samples. Red horizontal line indicates the maximum Bray-Curtis dissimilarity between replicate control samples. Each plot ends on the day preceding the prescription of antibiotics for treatment of exacerbation.