Overview of Lower Respiratory Tract Infections: Diagnosis and Treatment

Pneumonia is the sixth most common cause of death in the United States and a significant cause of death worldwide⁽¹⁾. In recent years, a number of new advances have occurred with regard to pneumonia diagnosis and treatment, including identification of new pathogens such as Chlamydia pneumoniae, hantavirus, and others, and the development of newer therapeutic agents such as fluoroquinolones, macrolides, streptogramins, oxazolidinones, and β-;actam antibiotics⁽²⁾. Additionally, new diagnostic tools such as nucleic acid amplification techniques and antigen detection methods provide hope that the speed and accuracy of diagnosis and the effectiveness of therapy will improve. Despite these advances, respiratory tract infections remain problematic both in diagnostic and therapeutic decision-making arenas.

Pneumonia is suspected in patients who have fever and cough coupled with an abnormal chest x-ray. Unfortunately, this combination of findings also may be attributable to noninfectious causes such as pulmonary thromboembolic disease, congestive heart failure, pulmonary hypersensitivity reactions, and other etiologies. In addition to the difficulty of differentiating pneumonia from noninfectious causes of fever, cough, and pulmonary infiltrates, defining the microbial etiology of pneumonia is problematic. With meningitis, bacterial endocarditis, or urinary tract infections, a positive culture of the appropriate clinical specimen strongly predicts its microbial cause. Microbial diagnosis of pneumonia etiology, however, is complicated by the problems of upper airway contamination of specimens. In addition to these difficulties, antibiotic resistance of usual respiratory tract pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis continues to increase^(3-;5).

GUIDELINES FOR THE MANAGMENT OF COMMUNNITY-ACQUIRED PNEUMONIA

Because of the challenges of both diagnosing and treating pneumonia, a number of professional organizations have developed treatment guidelines to give physicians parameters for diagnosis and disease management. In 1993, the American Thoracic Society (ATS), British Thoracic Society, and Canadian Infectious Disease Society all published guidelines on treatment of community-acquired pneumonia (CAP)^(6-;8). In 1998, the Infectious Diseases Society of America (IDSA) published its CAP management guidelines⁽⁹⁾. In the year 2000, IDSA, Canadian Infectious Disease and Thoracic Societies, and the Drug-;Resistant Streptococcus pneumoniae Therapeutic Working Group (DRSPWG) published new or revised guidelines for treatment of CAP ², ¹⁰, ¹¹). In 2001, the ATS published their revised guidelines for CAP ⁽¹²⁾. The newest guidelines...