Community-acquired pneumonia (CAP) is defined as an acute infection of the pulmonary parenchyma in a patient who has acquired the infection in the community, as distinguished from hospital-acquired (nosocomial) pneumonia. A third category of pneumonia, designated "healthcare-associated pneumonia," is acquired in other healthcare facilities such as nursing homes, dialysis centers, and outpatient clinics or within 90 days of discharge from an acute or chronic care facility. (See "Epidemiology, pathogenesis, microbiology, and diagnosis of hospital-acquired, ventilator-associated, and healthcare-associated pneumonia in adults".)
CAP is a common and potentially serious illness. It is associated with considerable morbidity and mortality, particularly in elderly patients and those with significant comorbidities . (See "Prognosis of community-acquired pneumonia in adults".)
The diagnostic approach to CAP in immunocompetent adults will be reviewed here. A variety of other important issues related to CAP are discussed separately. These include:
The approach to the patient with community-acquired pneumonia (CAP) begins with the clinical evaluation followed by chest radiograph with or without microbiologic testing . A systematic review highlighted the lack of sensitivity of the clinical criteria for an accurate diagnosis of CAP; even a combination of symptoms (cough) and signs (fever, tachycardia, and crackles) did not have a sensitivity above 50 percent when using chest x-ray as the standard .