Moraxella catarrhalis in chronic obstructive pulmonary disease: burden of disease and immune response.
BACKGROUND
Moraxella catarrhalis is frequently present in the sputum of adults with chronic obstructive pulmonary disease (COPD). Little is known about the role of M. catarrhalis in this common disease.


OBJECTIVE
To elucidate the burden of disease, the dynamics of carriage, and immune responses to M. catarrhalis in COPD.


METHODS
Prospective cohort study of 104 adults with COPD in an outpatient clinic at the Buffalo Veterans Affairs Medical Center.


METHODS
Clinical information, sputum cultures, molecular typing of isolates, and immunoassays to measure antibodies to M. catarrhalis.


RESULTS
Over 81 months, 104 patients made 3,009 clinic visits, 560 during exacerbations. Molecular typing identified 120 episodes of acquisition and clearance of M. catarrhalis in 50 patients; 57 (47.5%) of the acquisitions were associated with clinical exacerbations. No instances of simultaneous acquisition of a new strain of another pathogen were observed. The duration of carriage of M. catarrhalis was shorter with exacerbations compared with asymptomatic colonization (median, 31.0 vs. 40.4 days; p = 0.01). Reacquisition of the same strain was rare. The intensity of the serum IgG response was greater after exacerbations than asymptomatic colonization (p = 0.009). Asymptomatic colonization was associated with a greater frequency of a sputum IgA response than exacerbation (p = 0.009).


CONCLUSIONS
M. catarrhalis likely causes approximately 10% of exacerbations of COPD, accounting for approximately 2 to 4 million episodes annually. The organism is cleared efficiently after a short duration of carriage. Patients develop strain-specific protection after clearance of M. catarrhalis from the respiratory tract.
Murphy
Timothy F
TF
Buffalo Veterans Affairs Medical Center (151), 3495 Bailey Avenue, Buffalo, NY 14215, USA. murphyt@buffalo.edu
Brauer
Aimee L
AL
Grant
Brydon J B
BJ
Sethi
Sanjay
S
D000368:Aged; D000917:Antibody Formation; D002353:Carrier State; D017281:Cost of Illness; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000097:blood; D001936:Moraxella catarrhalis; D045828:Moraxellaceae Infections / Q000150:complications* / Q000276:immunology / Q000503:physiopathology*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology*; D013183:Sputum / Q000737:chemistry / Q000382:microbiology; D013997:Time Factors
D007070:Immunoglobulin A; D007074:Immunoglobulin G