Chest
Volume 118, Issue 6, December 2000, Pages 1557-1565
Journal home page for Chest

Clinical Investigations
COPD
Airway Inflammation and Etiology of Acute Exacerbations of Chronic Bronchitis

https://doi.org/10.1378/chest.118.6.1557Get rights and content

Study objectives:

The etiologic role of bacterialpathogens isolated from sputum culture in 40 to 50% of acuteexacerbations of chronic bronchitis (AECB) is controversial. Ifbacterial pathogens cause these AECB, they should be associated withgreater neutrophilic airway inflammation than pathogen-negativeexacerbations.

Design:

This hypothesis was tested bycomparing levels of interleukin (IL)-8, tumor necrosis factor(TNF)-α, and neutrophil elastase (NE) in 81 sputum samples obtainedfrom 45 patients with AECB. Four groups were compared. In the firstthree groups, nontypeable Haemophilus influenzae(n = 20), Haemophilus parainfluenzae (n = 27), andMoraxella catarrhalis (n = 14) were isolated as solepathogens, respectively. In the fourth group, only normal flora wasisolated (n = 20). Paired samples, obtained from individual patientsat different times, that differed in their culture results were alsocompared.

Setting:

An outpatient research clinic at a, Veterans Affairs Medical Center.

Patients:

Thesepatients were participating in a prospective, longitudinal study of thedynamics of bacterial infection in chronic bronchitis, for which theywere seen in the study clinic on a monthly basis as well as when theywere experiencing symptoms suggestive of AECB.

Interventions:

None.

Measurements andresults:

H influenzae exacerbations wereassociated with significantly higher sputum IL-8, TNF-α, and NE.M catarrhalis exacerbations demonstrated significantlyhigher sputum TNF-α and NE when compared to pathogen-negativeexacerbations. H parainfluenzae-associated exacerbationshad an inflammatory profile similar to pathogen-negative exacerbations. Sputum elastase level distinguished bacterial from nonbacterial AECBand correlated with clinical severity of the AECB.

Conclusions:

Increased airway inflammation associated withisolation of H influenzae and Mcatarrhalis supports an etiologic role of these pathogens in, AECB.

Section snippets

Chronic Bronchitis Study Clinic

The Human Studies Subcommittee of the Department of Veterans Affairs Western New York Healthcare system approved our study protocol. All participants gave written informed consent. A total of 74 patientswere enrolled in a prospective, longitudinal study of the dynamics andimmune response to bacterial infection in chronic bronchitis from March1994 to December 1997. Inclusion criteria were as follows: (1) thepresence of chronic bronchitis as defined by the American Thoracic Society, 15 (2) the

Patient Demographics

As shown in Table 2, our population was predominantly an elderly male population. Onenrollment, 26 of the subjects (58%) had severe COPD(FEV1 < 50% predicted), 12 subjects (27%) hadmoderate COPD (FEV1 of 50 to 64% predicted), 2subjects (4%) had mild COPD (FEV1 of 65 to 80% predicted), and 5 subjects (11%) had chronic bronchitis only.

Comparison of Expectorated and Induced Sputa

The only significant differences between the induced andexpectorated sputa were that the expectorated sputa were more purulentand viscous on gross examination than

Discussion

Several new research approaches are being used to investigate therole of bacteria in the etiology of AECB. Bronchoscopy with culture ofdistal airway secretions during AECB has demonstrated that pathogenicbacteria are present in about 50% and are likely to be the etiologicagents.181920 We have shown development of strain-specificbactericidal antibodies to infecting strains of H influenzaeafter AECB, further supporting the role of bacteria in causing, AECB.21 Molecular typing of sputum isolates

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    Financial support provided by the Department of Veterans Affairs Merit Review.

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