ABSTRACT
Two diagnostic algorithms can be used in the case of ventilator-associated pneumonia (VAP) suspicion. One option is to treat every patient clinically suspected of having a pulmonary infection with new antibiotics, even when the likelihood of infection is low, arguing that several studies showed that immediate initiation of appropriate antibiotics was associated with reduced mortality (1-3). Here, the selection of appropriate empiric therapy is based on risk factors, local resistance patterns, and involves qualitative testing to identify possible pathogens, with antimicrobial therapy being adjusted according to culture results or clinical response (Fig. 1). This ‘‘clinical’’ approach has two potential advantages: first, no specialized microbiologic techniques are requested and, second, the risk of missing a patient who needs antimicrobial treatment is minimal, at least when all suspected patients are treated with new antibiotics. However, such a strategy leads to overestimation of the incidence of VAP because tracheobronchial colonization and noninfectious processes mimicking it are included. Qualitative endotracheal aspirate cultures contribute indisputably to the
diagnosis of VAP only when they are completely negative for a patient with no modification of prior antimicrobial treatment. In such a case, the negative-predictive value is very high and the probability of the patient having pneumonia is close to null (4).
