community-acquired pneumonia

community-acquired pneumonia

Pneumonia caused by an infection currently present in the community; CAP is the most common cause of infectious death–US, and number 6 killer overall; of the 57% of CAPs in which a pathogen is identified, S pneumoniae causes 60%, H influenzae 15%, Legionella pneumophila 10-15%, Staphylococcus aureus 2-10% Clinical Atypical pneumonia with delayed recognition; early SX are distinctly nonpulmonary–eg, dry cough, myalgia, arthralgia Diagnosis Pathogens in pleural fluid or blood cultures, Pneumocystis carinii in sputum or BAL, a 4-fold ↑ in Mycoplasma pneumoniae antibody titers, isolation of L pneumophila, or a 4-fold ↑ in L pneumophila antibody titers, or positive direct fluorescent antibody test for legionella, S pneumoniae antigen in serum, urine Risk factors Alcoholism, seizure disorders, smoking, immunosuppression