THE INTRABRONCHIAL MICROBIAL-FLORA IN CHRONIC-BRONCHITIS PATIENTS - ATARGET FOR N-ACETYLCYSTEINE THERAPY

Chronic bronchitis is common among smokers, often together with recurr ent infectious exacerbations. Streptococcus pneumoniae and Haemophilus influenzae are the pathogens traditionally considered most important. N-acetylcysteine (NAC) treatment has been shown to reduce the number of infectious exacerbations in patients with chronic bronchitis. The m echanism behind this is unknown. We attempted to characterize the intr abronchial bacterial flora in patients with chronic bronchitis in an i nfection-free interval, and to determine whether pharmacological and i mmunological factors effected the bacterial occurrence. Twenty two smo kers with non-obstructive chronic bronchitis, 19 smokers with chronic bronchitis and chronic obstructive pulmonary disease (COBB) and 14 hea lthy nonsmokers underwent bronchoscopy. To obtain uncontaminated intra bronchial samples, a protected specimen brush was used. Quantitative b acterial cultures and virus isolations were performed. Significantly p ositive bacterial cultures (>1,000 colony-forming units (cfu).ml(-1)) were found only in the patients. S. pneumoniae and H. influenzae were found in five patients, and only in the patients without NAC treatment . The most common bacterium was alpha-haemolytic streptococcus. Negati ve cultures were more common in the healthy controls. Of the various f actors examined, only NAC medication had an influence on bacterial num bers. Significantly fewer patients with NAC meditation had positive cu ltures (3 out of 16) than in the group of patients without NAC therapy (15 out of 21). Our results confirm that chronic bronchitis in smoker s leads to increased intrabronchial bacterial colonization. We could a lso confirm that 1,000 cfu.ml(-1) is an adequate cut-off level for sig nificant bacterial growth when using the protected specimen brush. NAC medication was associated with low bacterial numbers.