An Overview of Community-acquired Respiratory Tract Infections

Community-acquired respiratory tract infections continue to be among the most common and important infections seen by practicing clinicians. These infections not surprisingly have some common aspects in regards to the microbes involved as well as their pathogenesis and typically involve the sinuses, the airways, and the lungs. Acute respiratory tract infections can be caused by a wide variety of microorganisms including viruses. This variety of respiratory pathogens is, in part, why the diagnosis and therapy of these infections remains a problem. The lack of rapid, accurate, and reliable methods for diagnosis makes it difficult to direct antimicrobial therapy at a specific pathogen. Thus, empirical therapy with broad-spectrum antimicrobial agents often is relied upon due to the absence of Gram’s stain and culture results. As viruses can cause many of these community-acquired respiratory tract infections, overuse of empirical antimicrobial therapy frequently occurs. Empirical antimicrobial therapy is not only ineffective against viral respiratory tract infections, but overuse of such therapy can lead to microbial resistance. Indeed, resistance has occurred with many of the bacterial pathogens causing community-acquired respiratory tract infections. Yet, effective antimicrobial therapy of respiratory tract infections caused by bacterial pathogens is important in preventing hospitalization or decreasing length of hospitalization. As a rule, acute respiratory tract infections caused by viruses are self-limited and should not be treated. A notable and recent exception is influenza, which has become relatively easy to diagnose and treat. This overview will focus primarily on community-acquired respiratory tract infections that are caused by those pathogens, including the influenza virus, which can be treated. Community-acquired respiratory tract infections that are caused by such pathogens include acute bacterial sinusitis, influenza, Chlamydophila pneumoniae respiratory tract syndrome, acute exacerbations of chronic bronchitis, and community-acquired pneumonia. (Adv Stud Pharm. 2005;2(6):212-218)