ABSTRACT
New York at Buffalo, and Department of Veterans Affairs, Western New York Healthcare System,
Buffalo, New York, U.S.A.
I. Introduction
A healthy lung, in spite of repeated exposure to microbial pathogens by inhalation and
microaspiration, has a remarkable ability to maintain sterility (1,2). In COPD, this
ability is compromised, and infections, both acute and chronic, become a prominent
feature of the disease. Acute lower respiratory tract infection in COPD can present as
either a tracheobronchial process, usually referred to as exacerbation, or involve the
lung parenchyma, with an infiltrate seen on chest X ray, whence it is called pneumonia.
Chronic infection in COPD is much more subtle in its clinical manifestations. In fact,
whether chronic infection has any clinical significance has been an area of controversy,
and is often referred to as “colonization,” implying it is innocuous.
