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

Blood and sputum cultures should be obtained in; 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

Guidelines no longer recommend prolonged treatment

Therapy may be extended based on slow clinical improvement, or radiological and laboratory parameters

Pseudomonas, Acinetobacter, Stenotrophomonas and Staph aureus HAP/VAP may require longer duration of treatment

Procalcitonin is useful in determining duration; normalization warrants stopping treatment, a 50% reduction indicates improvement and step-down may be considered

Cultures are helpful in guiding therapy, especially if organisms are present on the gram stain

Refrain from treating candida in the sputum unless suspecting systemic candidiasis (e.g. neutropenic, transplant patients)

Cultures may continue to be positive despite treatment in ventilated patients; refrain from re-culturing if patient improving