Conformity of bacterial growth in sputum and contamination free endobronchial samples in patients with cystic fibrosis.

The use of sputum cultures to guide the antimicrobial treatment of patients with cystic fibrosis has been questioned. Bacterial growth and antibiotic susceptibility patterns of 33 culture pairs from sputum and contamination free endobronchial swabs from 14 patients with cystic fibrosis were compared. As expected, Pseudomonas aeruginosa of the mucoid and non-mucoid type, Staphylococcus aureus, and Haemophilus influenzae were the organisms most frequently found. Absolute or good agreement was found in 73% of the culture pairs. The accuracy of the sputum cultures improved with the duration of antimicrobial treatment. The extra information gained from the endobronchial culture did not change the antimicrobial strategy from that based on the sputum culture alone. It is concluded that sputum cultures provide accurate information about the bacterial colonisation of the lower respiratory tract in patients with cystic fibrosis and therefore can be trusted both at onset of treatment and during the entire treatment period.