In the recent years, many investigators favour invasive techniques for diagnosis of pneumonia (protected-speci-men brush -PSB-or bronchoalveolar lavage-BAL-) that may have more diagnostic accuracy [76] [77] [78] [79] [80] . In PSB, 0.001 mL of secretions are collected and the presence of >10 3 cfu/mL bacteria has 80-90% sensitivity and 95% specificity for the diagnosis of VAP. In BAL, larger proportion of lung can be sampled and the diagnostic threshold is >10 4 cfu/mL. The sensitivity and specificity of BAL are 86-100% and 95-100%, respectively [76, [81] [82] [83] . Heyland and colleagues [84] proposed that PSB or BAL may increase physician confidence in the diagnosis and management of VAP and allows for greater ability to limit or discontinue antibiotic therapy. Also in this study, patients who underwent bronchoscopy with PSB and BAL had a lower mortality rate compared with patients who did not undergo bronchoscopy. However, a recent meta-analysis concluded that regular use of bronchoscopy for the diagnosis of VAP does not alter mortality, because it does not directly affect the initial antibiotic prescription [85] . The disadvantages of these invasive techniques are [71, 86, 87] ; a) prior antibiotic use may decrease the sensitivity and accuracy of these methods. However, in a recent study, Souweine et al. [88] reported that if a current antibiotic treatment prescribed for a prior infectious disease other than VAP, the diagnostic accuracy of protected specimen brush or bronchoalveolar lavage is not changed, b) these techniques are based on quantitative culture and results of these cultures require 24-48 hours, and, therefore miss early cases, and also give no information about appropriate initial antibiotic therapy, c) these invasive tests may worsen the patient's status (cardiac arrhythmias, hypoxemia, bleeding, etc.), d) increase the costs of caring, e) it has not been proven that the use of these invasive techniques lead to a decrease in patients' mortality.