Community-acquired pneumonia: the clinical dilemma.

Community-acquired pneumonia (CAP) is the sixth most common cause of death in the United States. Despite its frequency and mortality, specific etiologic diagnosis remains a major clinical challenge. The organisms most commonly implicated in CAP are Streptococcus pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, Haemophilus influenzae, Chlamydia pneumoniae (TWAR), and viruses. Clinical and radiographic criteria have proven to be of little value in determining the etiology of CAP. Laboratory studies, including Gram's stain and culture of sputum, have also been shown to be of severely limited value to the clinician faced with the patient with CAP. Antibiotic therapy must, therefore, generally be empiric. Regimens including erythromycin either as a single agent or coupled with an aminoglycoside or cephalosporin appear to be most efficacious.