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Abstract
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 exacerbations.
This hypothesis was tested by comparing levels of interleukin (IL)-8, tumor necrosis
factor (TNF)-alpha, and neutrophil elastase (NE) in 81 sputum samples obtained from
45 patients with AECB. Four groups were compared. In the first three groups, nontypable
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 compared.
An outpatient research clinic at a Veterans Affairs Medical Center.
These 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.
None.
H influenzae exacerbations were associated with significantly higher sputum IL-8,
TNF-alpha, and NE. M catarrhalis exacerbations demonstrated significantly higher sputum
TNF-alpha 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.
Increased airway inflammation associated with isolation of H influenzae and M catarrhalis
supports an etiologic role of these pathogens in AECB.