The aetiologic diagnosis of ventilator-associated pneumonia (VAP) is a microbiological emergency because of its impact on the morbidity and mortality of the disease. Lower respiratory tract samples should be obtained before treatment is commenced or modified. Surveillance cultures are not recommended when there is no suspicion of VAP. Bronchoscopic techniques do not seem to offer clear benefits over noninvasive methods. It is essential that microbiological tests provide quantitative results such that bacterial colonisation is distinguished from infection.
Bacterial identification and antibiotic susceptibility tests take 2–4 days, so there is a need for rapid diagnostic procedures. Rapid information is clearly more beneficial to the patient than more complete but delayed information. Gram staining, quantifying microorganisms in polymorphonuclear cells in bronchoalveolar lavage samples and antibiograms prepared directly from clinical samples may provide rapid information that reasonably correlates with subsequent culture results.
Better communication between microbiologists and attending physicians will improve the VAP management. Microbiological information is also key to preparing guidelines for the empirical treatment of these patients in each hospital unit.