Despite the increasing number of studies on ventilator-associated pneumonia, the clinical utility of the available diagnostic methods remains unknown. Although the study by Kollef and colleagues [1] shows similar numbers of positive cultures obtained by the protected specimen brush and minibronchoalveolar lavage techniques, the results do not support the routine clinical use of either method.

A major flaw in this study is that more than half of the patients were receiving antibiotics, which have been shown to significantly affect endobronchial evaluation of ventilator-associated pneumonia. For example, both bronchoalveolar lavage and protected specimen brushing yield many false-positive cultures in intubated patients receiving antibiotics, presumably because of colonization or contamination [2].

Thus, in patients receiving antibiotics, attempts to diagnose ventilator-associated pneumonia are of questionable benefit, and several authorities have recommended against endobronchial evaluation in this group [3, 4].

Protected specimen brushing is highly accurate for sampling a given area. In contrast, although the minibronchoalveolar lavage catheter is directed toward the desired lung to be sampled, a specific lung segment or subsegment could probably not be deliberately accessed. Radiographic validation might have been useful to confirm catheter placement.

Kollef and colleagues found that minibronchoalveolar lavage resulted in slightly more positive cultures than did protected specimen brushing. This finding is not surprising, given that the latter method is more specific. However, even if minibronchoalveolar lavage is more sensitive than protected specimen brushing in diagnosing ventilator-associated pneumonia, a lower specificity may negate its usefulness.

As the authors acknowledge, evaluation of the utility of minibronchoalveolar lavage is ultimately limited by the lack of a "gold standard." Thus, the value of comparing different techniques in diagnosing ventilator-associated pneumonia seems questionable.