A diagnosis of community-acquired pneumonia (CAP) was established in any patient presenting with a combination of fever, cough and purulent sputum, shortness of breath, chest pain, and new consolidation on chest X-ray or computed tomography. The severity of pneumonia was assessed the first 24 hours of admission according to Confusion, Urea nitrogen, Respiratory rate, Blood pressure (CURB) index. Patients having two or more criteria were identified to have severe pneumonia [24] . Sepsis, severe sepsis and septic shock were defined according to current recommendations [25] . Pneumonia was considered to be absent when: i) an alternative cause for pulmonary infiltrate was established (e.g. pulmonary embolus) and ii) full recovery was achieved without antimicrobial therapy.