A type of bacterium once believed to be unrelated to chronic obstructive pulmonary disease (COPD) may, in fact, be responsible for a small number of flare-ups associated with the common illness, says a new study.1
Scientists at the University of Buffalo in New York claim the bacterium, Moraxella catarrhalis, is responsible for up to 4 million flare-ups of COPD that occur each year in the United States.
"This paper is the first to study the involvement of M. catarrhalis in a prospective way in adults with COPD," said Timothy F. Murphy, MD, a professor of Medicine and Microbiology at the university, who headed the research. "Using rigorous methods, our work has shown that acquiring M. catarrhalis is strongly associated with the onset of symptoms of an exacerbation."
A Leading Cause of Death
Chronic obstructive pulmonary disease is a slowly progressive ailment characterized by gradual loss of healthy lung function. The term COPD represents a spectrum of pulmonary illnesses that includes chronic bronchitis and emphysema. Symptoms of COPD include a constant cough, and sputum production, as well as shortness of breath in later stages. The major documented cause of COPD is cigarette smoking, as well as exposure to secondary smoke. However, exposures to certain job-related dusts and chemicals, as well as outdoor pollution are other possible causes.2
It's estimated that some 12 million people in the United States were diagnosed with the disease in 2001, the latest year for which estimates are available.2 Yet Murphy believes as many as 20 million people in this country may be afflicted.
A common complication of COPD is pulmonary hypertension, a disease characterized by an abnormal increase in blood pressure in the pulmonary artery running between the heart and lungs. Yet experts say the blood pressure increase in PH cases associated with COPD is typically mild to moderate.3
Previously Unrecognized Link
People who have [COPD] experience one to two flare-ups per year, Murphy explained. "If 10% of all exacerbations are caused by M. catarrhalis, that translates to two to four million exacerbations annually," he said.
The bacterium is typically responsible for a range of respiratory infections, including sinusitis, bronchitis and pneumonia. It's also mentioned as a cause of laryngitis in adults, as well as ear and eye infections in children.4
To determine the prevalence of the bacterium in COPD, Murphy's team conducted a prospective study of 104 people with the illness being treated at an outpatient VA clinic in the Buffalo area. The researchers obtained demographic information from each participant, as well as sputum cultures (the bacterium is commonly found in the sputum of COPD patients). They also measured levels of antibodies to M. catarrhalis.
Each patient was followed for nearly seven years, during which time they collectively made more than 3,000 visits to the clinic. Of all the visits, about 20% were for COPD flare-ups. Murphy and his colleagues eventually found that M. catarrhalis had been acquired by 50 people with COPD, and nearly half of those were related to COPD flare-ups. The study team found no cases in which another disease-causing organism was involved.
On a positive note, people with symptom flare-ups directly caused by M. catarrhalis tended to be infected with the bacterium for a shorter period than those with no flare-ups. Antibody responses were greater after flare-ups than in people who were infected with the bacterium with no exacerbations, the researchers learned.
A Vaccine May be Necessary
Based on the findings, Murphy says it's logical to consider pursuing the development of a vaccine to prevent these bacterial infections in people with COPD. "Exacerbations cause enormous morbidity and health care costs," he said. "They lead to physician visits, emergency room visits, hospital admissions and respiratory failure requiring mechanical ventilation."
With this expanded knowledge about the bacterium's role in provoking COPD symptoms, "we have even more reason to forge ahead with developing a vaccine," Murphy maintained.
1. Murphy TF, Brauer AL, Grant BJ, Sethi S. 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. Epub 2005 Apr 1.
2. National Heart, Lung and Blood Institute. National Institutes of Health (NIH). Chronic Obstructive Pulmonary Disease. Available at: http://www.nhlbi.nih.gov/health/public/lung/other/copd_fact.pdf. Accessed August 18, 2005.
3. Naeije R, Barbera JA. Pulmonary hypertension associated with COPD. Crit Care 2001 Dec;5(6):286-9. Epub 2001 Nov 3.
4. Verduin CM, Hol C, Fleer A, van Dijk H, van Belkum A. Moraxella catarrhalis: from emerging to established pathogen. Clin Microbiol Rev 2002 Jan;15(1):125-44.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
