Value of gram stain examination of lower respiratory tract secretions for early diagnosis of nosocomial pneumonia

Except for bronchoalveolar lavage, the value of the Cram stain examination of respiratory tract samples for the diagnosis of hospital-acquired pneumon ia (HAP) and their potential impact on empiric antibiotic treatment have ra rely been assessed. During a 14-mo period, both plugged telescoping cathete r (PTC) and endotracheal aspirate (EA) were performed when an HAP was suspe cted in mechanically ventilated patients. The results of Cram stain examina tions and cultures and previous and subsequent antibiotic treatment were pr ospectively recorded. Two criteria for pneumonia were considered: (1) clini cally diagnosed pneumonia, according to attending physicians, based on clin ical and radiological evolution and the PTC culture results, and (2) microb iologically proven pneumonia (solely based on the result of quantitative PT C culture). Of 91 episodes of suspected HAP in 51 patients, 27 (30%) episod es were clinically diagnosed as pneumonia. When considering clinically diag nosed pneumonia, the sensitivity and specificity of Cram stain examination were similar (respectively, 89% and 62% for EA and 67% and 95% for PTC). Wh en considering microbiologically proven pneumonia, the sensitivity and spec ificity of Cram stain examination were, respectively, 91% and 64% for EA an d 70% and 96% for PTC. The negative predictive value of Gram stain examinat ion of EA and the positive predictive value of Gram stain examination of PT C were high. Our results suggest that the combination of Cram stain examina tion of paired PTC and EA may contribute to the early diagnosis of HAP in a bout two-thirds of mechanically ventilated patients, and guide the empiric therapy when needed. In the remaining one-third of patients, the Gram stain examination is not helpful in predicting HAP.