Accuracy of diagnostic tools for the management of nosocomial respiratory infections in mechanically ventilated patients.

This article reviews the medical literature concerning available diagnostic tools for managing nosocomial respiratory infections in mechanically ventilated patients. The first part deals with the reliability of the clinical criteria used in diagnosing nosocomial pneumonia in such patients and the accuracy of simple markers of pneumonia such as elastin fibres stain and antibody-coated bacteria. The second part reviews the presently available non-invasive and invasive methods for diagnosing pulmonary infections acquired during mechanical ventilation. With regard to invasive methods, protected specimen brush and bronchoalveolar lavage are extensively discussed in view of the different results in the literature. At the present time, these two methods seem to be the most accurate techniques available. The fact that bronchoalveolar lavage may combine the cytological examination and the quantitative culture of the sample obtained is noted. The role of percutaneous lung needle aspiration is also mentioned. Finally, histological diagnosis of pneumonia and pulmonary postmortem biopsy cultures are reviewed as "gold-standard" reference methods for investigation in this field. Future directions for further clinical research are addressed.