DIAGNOSIS OF VENTILATOR-ASSOCIATED PNEUMONIA - AN EVALUATION OF DIRECT EXAMINATION AND PRESENCE OF INTRACELLULAR ORGANISM

Background: Ventilator-associated pneumonia (VAP) requires early diagn osis and adequate antibiotic therapy. The aim of this prospective post mortem study was to assess the accuracy of direct examination and quan tification of intracellular organisms (ICO) for the diagnosis of VAP. Methods: Total and differential cell counts were performed on fluids r ecovered using nonbronchoscopic sampling techniques (blind bronchial s ampling [BBS], mini-bronchoalveolar lavage [mini-BAL]) and from bronch oalveolar lavage (BAL) performed during fiberscopy. These 3 sampling t echniques were done within 15 min of death without discontinuing mecha nical ventilation. Quantification of ICO was performed on each sample recovered from the various sampling procedures. Gram reaction and morp hology of bacteria were evaluated on Gram smears. Results: The results of each technique were compared with histology and culture of lung ti ssue specimens obtained by surgical pneumonectomies in 28 patients who died after at least 72 h of mechanical ventilation. Histology was pos itive ia 15 patients and negative in 15 patients. When only VAP with p ositive lung culture was considered (histologic signs of bronchopneumo nia plus positive lung tissue culture), the sensitivity of Gram staini ng on BAL, mini-BAL, and BBS was 56%, 44%, and 56%, respectively. If a ll samples were considered, the sensitivity and the specificity of the determination of the percentage of ICO were low (less than 70%) whate ver the sampling technique. Conclusions: For initial therapeutic guida nce, direct examination and presence of ICO do not contribute for esta blishing the diagnosis of VAP, essentially because of a lack of sensit ivity. However, when positive, Gram staining can obviously guide initi al antibiotherapy.