1) Presence of two or more of the following: age > 65 years; chronic pulmonary disease; congestive heart failure; chronic kidney failure; chronic liver disease; malignant neoplasm; diabetes mellitus; hospitalization for pneumonia during the past year.
2) Respiratory rate ≥ 30 / minute.
3) Low blood pressure: systolic < 90 and/or diastolic: < 60 mmHg).
4) Poor respiratory mechanics. (paradoxical respiration. Circulation. etc.).
5) Any of the following: PaO2 < 60 mmHg; SaO2 < 89%; PaCO2 > 50 mmHg with acidosis; white blood cell count < 4000 or > 30.000/mm3; BUN > 25 mg/dl; hematocrit < 30%.
6) Alteration of consciousness.
7) Serious swallowing disorder suggesting likely aspiration.
8) Suppurative complications (pericarditis. Arthritis. empyema. Etc.)
9) Severe chest radiograph involvement (multilobar, bilateral, cavitation, progression > 50% over a previous RX)
10) Reasons suggesting inaccurate treatment compliance.