A diagnosis of pneumonia generally requires a demonstration of an infiltrate of chest imaging; X-rays may be negative in immunocompromised hosts or severely dehydrated patients
Fever, dyspnea, cough and sputum production comprise clinically compatible symptoms
NP swabs for respiratory viruses (influenza, enterovirus, rhinovirus) are recommended during flu season for CAP
Blood and sputum cultures should be obtained in hospitalized/ED patients; noninvasive sampling is preferred
Procalcitonin of > 0.5 mcg/L (>0.25 mcg/L in ICU patients) has a high positive predictive value for bacterial pneumonia. Antibiotics are discouraged when PCT is negative (<0.25mcg/L)
Legionella urine antigen can be ordered on inpatients if interstitial/atypical X-ray findings or risk factors (hot tub exposure, travel)
Serology (IgM) for mycoplasma is no longer indicated
The Respiratory Pathogen Panel (RPP) tests for 22 different respiratory pathogens by PCR, including atypical organisms and viruses, and can be ordered in patients in the ICU or upon approval from Medical Microbiology
In patients with cavitary pneumonia consider TB, fungal pathogens and Nocardia
In immunocompromised patients consider opportunistic pathogens such as PJP, CMV and fungal pathogens
