CAP-MarkerUse of Procalcitonin (PCT) and C-reactive Protein (CRP) to Guide Antibiotic Therapy in Community Acquired Pneumonia: a Randomized Controlled Trial

Methods • Patients and settings: All adult (> 18 years old) patients with diagnosis community-acquired pneumonia will receive initial antibiotic therapy based on local guidelines and susceptibility patterns, according to the decision of the treating physician.Patients will be randomly assigned to one of two groups, which respectively include PCR and PCT clinical procedure protocol. Randomization will be done using a table of random numbers generated by computer. For practical reasons the doctors treating the patients in question have science group in which the patient was included. Patients included in the two groups will have baseline assessment during the first day of study: * Clinical evaluation of basic * Start of antibiotic therapy * Inclusion in the study * Randomization (after signing the Informed Consent) * Interventions: They will have circulating PCT and CRP levels measured at baseline and days 1,2,3 e 5 in both groups. Group 1 - CRP group: the duration of antibiotic therapy will be based on circulating CRP levels. Group 2 - PCT group: the duration of antibiotic therapy will be based on circulating PCT levels. Patients enrolled in the study will undergo daily measurements of plasma CRP (Dry Chemistry - Johnsons \& Johnsons) and PCT (BRAHMS PCT VIDAS) levels up to day 5, and then, every 48hr in patients remaining in the ICU, and every 5 days in those transferred to the ward. Patients will be followed up 28 days, or until death or hospital transference, which comes first. PCT and CRP results will be released in sealed envelopes. During the study period, only the results corresponding to the patient randomization group will be open; i.e., CRP for CRP group patients and PCT for PCT group patients. Criteria for antibiotic interruption: The investigators will propose the interruption of antibiotics if: 1. The patients is clinically stable, without signs of active infection 2. CRP group: a relative reduction of 50% in baseline CRP levels, or a value lower than 25mg/dl is reached. 3. PCT group: a relative reduction of 90% in baseline PCT levels, or if a absolute value lower than 0.1 ng/ml is reached. The final decision regarding antibiotic therapy will be always let to the discretion of the treating physician.