Moraxella catarrhalis in chronic obstructive pulmonary disease: burden of disease and immune response

Am J Respir Crit Care Med. 2005 Jul 15;172(2):195-9. doi: 10.1164/rccm.200412-1747OC. Epub 2005 Apr 1.


Rationale: 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.

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

Main 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Antibody Formation
  • Carrier State
  • Cost of Illness*
  • Humans
  • Immunoglobulin A / analysis
  • Immunoglobulin G / blood
  • Moraxella catarrhalis*
  • Moraxellaceae Infections / complications*
  • Moraxellaceae Infections / immunology
  • Moraxellaceae Infections / physiopathology*
  • Prospective Studies
  • Pulmonary Disease, Chronic Obstructive / complications*
  • Pulmonary Disease, Chronic Obstructive / immunology
  • Pulmonary Disease, Chronic Obstructive / microbiology
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • Sputum / chemistry
  • Sputum / microbiology
  • Time Factors


  • Immunoglobulin A
  • Immunoglobulin G