EFFECT OF PREVIOUS ANTIMICROBIAL THERAPY ON THE ACCURACY OF THE MAIN PROCEDURES USED TO DIAGNOSE NOSOCOMIAL PNEUMONIA IN PATIENTS WHO ARE USING VENTILATION

We evaluated the effect of antibiotic treatment received before the su spicion of pneumonia on the diagnostic yield of protected specimen bru sh (PSB), direct examination (BAL D) and culture (BAL C) of lavage flu id on consecutive mechanically ventilated patients with suspected noso comial pneumonia. Bronchoscopy was always performed before any treatme nt for suspected pneumonia. One hundred and sixty-one patients with su spected pneumonia underwent PSB and BAL before any institution or chan ge in antibiotic therapy (AB). Sixty-five patients received AB for an earlier septic episode (ON AB group) and 96 patients did not (OFF AB g roup). All but two strains recovered were highly resistant to previous AB. Sensitivity and specificity of each test were not different betwe en the ON AB and OFF AB groups as well as the percentage of complete a greement between the 3 procedures, 74 and 67% respectively. We conclud e that previous AB received to treat an earlier septic episode unrelat ed to suspected pneumonia do not affect the diagnostic yield of PSB an d BAL.