Value of the serum procalcitonin level to guide antimicrobial therapy for patients with ventilator-associated pneumonia

Procalcitonin's contribution to the diagnosis of nosocomial infection, particularly ventilator-associated pneumonia (VAP), is poor: its levels in patients with microbiologically documented VAP the day infection is diagnosed range from normal to extremely high. Moreover, the results of four studies showed that, despite relatively good specificity, this marker had low sensitivity for the diagnosis of VAP. However, because procalcitonin is well associated with outcome, its kinetics during antimicrobial therapy can be used to customize that treatment duration. Two recent studies showed that a procalcitonin-based strategy (recommending that treating physicians stop antibiotics when the procalcitonin concentration was <0.5 ng/mL, or had decreased by ≥80%) led to less antibiotic consumption by VAP patients, compared with a conventional strategy, with no adverse outcome. Accordingly, for VAP patients, procalcitonin may be used to stop antibiotics as early as day 3 after their initiation, if its concentration is <0.5 ng/mL or has decreased by ≥80%, compared with the first peak concentration.