Do quantitative cultures of protected brush specimens modify the initial empirical therapy in ventilated patients with suspected pneumonia?

The real contribution of the protected specimen brush (PSB) to guide the choice of antimicrobial therapy in ventilated patients with severe pneumonia is not well established. This study aimed to assess how data obtained by PSB changed the initial empirical therapy. One hundred and ten ventilated patients with suspected pneumonia were entered into a prospective study. All patients underwent fibreoptic bronchoscopy within the first 24 h after clinical suspicion of pneumonia. Specimens were obtained by PSB and were processed for quantitative cultures using standard methods. When patients were started on empirical antibiotics, a standard therapeutic regimen was followed. The decision to introduce, withdraw, maintain, or modify antibiotic therapy, according to the PSB culture results, was left to the attending physician. Pneumonia was the final diagnosis in 45 (41%) of the 110 patients. Pneumonia was excluded in 47 (43%) patients and in the remaining 18 (16%) the diagnosis was uncertain. The initial therapeutic plans were considered to be adequate in 40 patients (36%) and inadequate in 37 cases (34%). In 17 patients (15%), therapeutic changes were made based on the results of PSB cultures. In one case appropriate antibiotics were introduced; in nine cases the therapeutic regimen was reduced to select a narrower and rational therapy; and in seven patients therapy was changed because the prescribed antimicrobial agents were ineffective against the organisms recovered. This study shows that therapeutic changes were made based on the results of PSB cultures in 38% of the patients with pneumonia. In contrast, the PSB technique has no impact on antimicrobial therapy of patients without pneumonia.