Published February 10, 2014
University at Buffalo researchers have revealed that patients with chronic obstructive pulmonary disease (COPD) experience more respiratory symptoms when their lungs are colonized by bacteria, even without an acute exacerbation.
“These findings demonstrate that it’s time for a paradigm shift in how we treat patients with stable COPD,” says senior author Sanjay Sethi, MD, professor of medicine and chief of pulmonary, critical care and sleep medicine.
“If the persistence of these bacteria contributes to increased symptoms and inflammation in the lungs in stable COPD, we should regard this as a chronic infection, not innocuous colonization,” says Sethi, who also directs the Buffalo VA Medical Center’s COPD Study Clinic and is a staff physician with the Veterans Affairs Western New York Healthcare System.
Conventional wisdom has held that even though bacteria persist in COPD patients’ lungs, their presence — or colonization — is innocuous, as long as the patient is not having a flare-up, or exacerbation, of respiratory symptoms.
However, this study proves that bacterial colonization is sufficient to trigger clinically significant increases in shortness of breath, cough and sputum in COPD patients.
“The lungs are constantly being exposed to microbes with every breath you take, as well as from aspiration of small amounts of secretions from the throat, especially during sleep,” he explains.
The study is the first to longitudinally analyze symptoms in COPD during bacterial colonization with a well-validated symptom assessment tool.
While emphasizing that more must be done to reduce chronic infections in COPD, Sethi says long-term antibiotics are not the answer because patients risk developing resistance.
“We need to go beyond traditional approaches of bronchodilation and anti-inflammatory agents to reduce symptoms,” Sethi says.
“We need to put more emphasis on developing therapies that can decrease bacterial colonization in COPD.”
“The role of infection in COPD is not fully documented and this finding helps add to our understanding of how it affects patients on a daily basis,” says Sethi.
Although most patients with stable COPD experience daily fluctuations in respiratory symptoms, the reasons behind these fluctuations are not fully understood.
Furthermore, although these fluctuations often qualify as exacerbations in terms of intensity and duration, only a third of them are reported.
“Bad days and unreported exacerbations are at least partially explained by bacteria causing inflammation in the lower airways in COPD,” he says.
The study followed 41 elderly male veterans with smoking-related COPD from October 2005 to January 2009.
The researchers used sensitive molecular detection methods, as well as conventional laboratory cultures, to detect four common bacterial pathogens encountered in COPD: Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Pseudomonas aeruginosa.
The study controlled for variables that could affect patients’ daily symptoms, including local air pollution levels and weather-related factors like humidity.
Funded by the U.S. Department of Veterans Affairs, the study received critical support and patient participation through the Buffalo VA Medical Center.
“We could not have done this study without the generous participation of our patients,” he says. “We can model inflammation and other effects of smoking using animals, but documenting respiratory symptoms can only be done with human subjects.”
Participants used electronic diaries to record daily symptoms of breathlessness, cough and sputum.
They provided sputum, blood samples and clinical information at the COPD Study Clinic each month, and also visited whenever they had exacerbations.
Additionally, they gave samples every two weeks from their homes.
The paper, “Bacterial Colonization Increases Daily Symptoms in Patients with Chronic Obstructive Pulmonary Disease,” has been published by the Annals of the American Thoracic Society.
UB co-authors include:
Additional co-authors include researchers and staff at the Buffalo and Fayetteville VA Medical Centers.