While chronic obstructive pulmonary disease (COPD) may or may not occur along with other respiratory illnesses such as pulmonary hypertension or lung fibrosis, if you are diagnosed with COPD, you may be more prone to develop an infection that is known to cause pneumonia.
Doctors in the U.S. and Canada have published a study that found a higher incidence of infection with a disease-causing microorganism known as Pneumocystis (new-moh-SIS-tis) in people with more severe forms of COPD.1
Pneumocystis organisms can cause pneumonia in people who have compromised immune systems. The organisms exist as yeast-like fungi, and scientists believe there are many different strains.2 The strain that only infects humans is known as Pneumocystis jerovici.3 Formerly, this strain was known as Pneumocystis carinii (PCP), which is well known as the cause of pneumonia in people with AIDS.4
Tracing a Potential Infection
In the study, Alison Morris, MD, with the division of Pulmonary and Critical Care Medicine at the University of Southern California and her colleagues studied lung tissue from 68 smokers who had undergone lung surgery or transplants due to various severe forms of COPD, looking for specific evidence of pneumocystis. The samples were compared with those of 44 people who had received lung transplants for reasons other than COPD, including idiopathic pulmonary fibrosis and cystic fibrosis.
The researchers found the colonies in more than a third of patients with severe COPD. Comparatively, only about 5 percent of smoking patients who had normal lung function or less severe COPD had these same colonies in their lung tissue, Morris and her colleagues discovered. About 9 percent of those who underwent transplants for reasons other than COPD also had pneumocystis colonies in their lung tissue.
"Colonized subjects exhibited more severe airway obstruction," the study team wrote. Those with the most advanced stage of COPD were at the highest risk of being infected with pneumocystis, they noted, irregardless of whether or not the patient was a smoker.
"We conclude that there is a strong association between Pneumocystis colonization and severity of airflow obstruction in smokers, suggesting a possible pathogenic link with COPD progression," they wrote.
A Disease Caused by Smoking
Chronic obstructive pulmonary disease, considered the fourth leading cause of death in the world, is an umbrella term for chronic bronchitis and asthma. Cigarette smoking is the most common cause of the disease, with most patients being smokers or former smokers. Breathing in pollution, dust, or certain chemicals over long periods of time, which can irritate the lungs, is also a risk factor for COPD. When the disease strikes, the airways and air sacs in the lungs lose their elasticity, the walls between many of the air sacs become destroyed, the airway walls become thick and inflamed, and cells in the airways make more mucous than normal, which clogs the airways themselves.5
One common complication in COPD is pulmonary hypertension (PH), in which the blood pressure in the pulmonary artery rises to abnormal levels. Experts say the presence and severity of PH depends on the prognosis of the individual with COPD.6
Likewise, COPD can occur simultaneously in people who have idiopathic pulmonary fibrosis (IPF), particularly in the context of emphysema and lung fibrosis. In fact, COPD may induce pulmonary fibrosis in some people.7
Pulmonary fibrosis is a scarring of the lung tissue that occurs when the air sacs gradually get replaced by fibrotic tissue. When the scarring forms, the tissue thickens, causing an irreversible loss of the lungs' ability to transfer oxygen into the bloodstream.8
1. Morris A, Sciurba FC, Lebedeva IP et al. Association of chronic obstructive pulmonary disease severity and Pneumocystis colonization. Am J Respir Crit Care Med 2004 Aug 15;170(4):408-13. Epub 2004 Apr 29.
2. Stringer JR. Pneumocystitis. Int J Med Microbiol 2002 Oct;292(5-6):391-404.
3. Pneumocystis carinii: an update. Ultrastruct Pathol 2003 Mar-Apr;27(2):115-22.
4. Hanano R, Kaufmann SH. Pneumocystis carinii and the immune response in disease. Trends Microbiol 1998 Feb;6(2):71-5.
5. National Heart, Lung and Blood Institute. National Institutes of Health (NIH). What is Chronic Obstructive Pulmonary Disease (COPD)?
6. Barbera JA, Peinado VI, Santos S. Pulmonary hypertension in COPD: old and new concepts. Monaldi Arch Chest Dis 2000 Dec;55(6):445-9.
7. Du M, Wang C, Cao D, Weng X, Wu X, Liu Y. A pathological study on pulmonary fibrosis caused by chronic obstructive pulmonary disease [Translated from Chinese]. Zhonghua Jie He He Hu Xi Za Zhi 1999 Jan;22(1):30-2.
8. Pulmonary Fibrosis Foundation. What is Pulmonary Fibrosis? Available at: http://www.pulmonaryfibrosis.org/ipf.htm. Accessed October 15, 2004.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
