Study objectives: The etiologic role of bacterial
pathogens isolated from sputum culture in 40 to 50% of acute
exacerbations of chronic bronchitis (AECB) is controversial. If
bacterial pathogens cause these AECB, they should be associated with
greater neutrophilic airway inflammation than pathogen-negative
Design: This hypothesis was tested by
comparing levels of interleukin (IL)-8, tumor necrosis factor
(TNF)-α, and neutrophil elastase (NE) in 81 sputum samples obtained
from 45 patients with AECB. Four groups were compared. In the first
three groups, nontypeable Haemophilus influenzae
(n = 20), Haemophilus parainfluenzae (n = 27), and
Moraxella catarrhalis (n = 14) were isolated as sole
pathogens, respectively. In the fourth group, only normal flora was
isolated (n = 20). Paired samples, obtained from individual patients
at different times, that differed in their culture results were also
Setting: An outpatient research clinic at a
Veterans Affairs Medical Center.
patients were participating in a prospective, longitudinal study of the
dynamics of bacterial infection in chronic bronchitis, for which they
were seen in the study clinic on a monthly basis as well as when they
were experiencing symptoms suggestive of AECB.
results:H influenzae exacerbations were
associated with significantly higher sputum IL-8, TNF-α, and NE.
M catarrhalis exacerbations demonstrated significantly
higher sputum TNF-α and NE when compared to pathogen-negative
exacerbations. H parainfluenzae-associated exacerbations
had an inflammatory profile similar to pathogen-negative exacerbations.
Sputum elastase level distinguished bacterial from nonbacterial AECB
and correlated with clinical severity of the AECB.
Conclusions: Increased airway inflammation associated with
isolation of H influenzae and M
catarrhalis supports an etiologic role of these pathogens in