Patients randomized to the study will undergo daily measurements of plasma PCT levels, and kept under antibiotic therapy until a relative reduction of 90% in baseline PCT levels, or a value lower than 0.5 ng/ml is reached, and then maintained for additional 48h (two measure). Therefore, plasma PCT levels will be measured every 5 days up to the 28th day of follow-up or until death or transference, if either occurs first. Patients included in the interventional group will be observed for at least 48 hours following antibiotic discontinuation before being discharged from the hospital. Extra PCT tests will be performed according to the clinical course.