The purpose of the study is to assess the efficacy of an individualized approach to duration of antibiotic therapy based on each subject's clinical response compared to a local standard approach in patients coming from the community and who are hospitalized because of a pneumonia.

Inclusion Criteria:

Patients will be 18 years old or older and meet all of the following inclusion criteria to be eligible for enrollment into the trial:

1. Diagnosis of pneumonia:

   Evidence of a new pulmonary infiltrate seen on either radiograph or computed tomography of the chest within 48 hours after hospitalization plus at least two among the following: 1) new or increased cough with/without sputum production and/or purulent respiratory secretions; 2) fever (documented temperature -rectal or oral- ≥ 37.8 °C) or hypothermia (documented temperature -rectal or oral- <36o C); 3) deterioration of oxygenation; 4) evidence of systemic inflammation (such as abnormal white blood cell count -either leukocytosis (>10,000/cm3) or leukopenia (< 4,000/cm3) - or increasing of C-reactive protein or procalcitonin values above the local upper limit.

   CAP will be defined as pneumonia occurring in any patient admitted to the hospital coming from the community and who were not hospitalized in the previous 14 days. HCAP will be defined as a community-acquired pneumonia occurring in a patient with any of the following special epidemiological characteristics: patient who was hospitalized for 2 days or more in the previous 90 days; patient coming from a nursing home or extended care facility; patient who received home infusion therapy (including antibiotics) or wound care in the previous 30 days; patient who was on chronic dialysis in the previous 30 days.

2. An appropriate empiric antibiotic therapy for the pneumonia received within 24 hours after admission to the hospital.

3. A clinical stability reached within 5 days after hospital admission, in the absence of any changes of the initial empiric antibiotic therapy.

4. Signed informed consent

Exclusion Criteria:

Patients presenting with any of the following will not be included in the trial:

1. Patients with immunodeficiency, defined as: chemotherapy in the previous 12 months, radiotherapy in the previous 12 months, transplantation, immunosuppressive treatment, hematologic malignancy, AIDS or HIV with CD4 count < 200, asplenia.
2. Patients with a concomitant infection on admission to the hospital requiring antibiotic therapy (i.e urinary tract infection). The presence of sepsis due to pneumonia will not be considered another concomitant infection.
3. Patients with documented bacteremia due to S. aureus in a blood culture (both methicillin resistant and susceptible S. aureus)
4. Patients with etiology of pneumonia due to fungi, mycobacterium or Pneumocystis jiroveci.
5. Patients hospitalized in the previous 15 days

Inclusion and exclusion criteria for the proposed study will not limit the study cohort on the basis of sex, ethnicity, socioeconomic status or other potentially discriminatory factors.