Comparison of direct examination of three types of bronchoscopy specimens used to diagnose nosocomial pneumonia

Objective: To compare direct examination of bronchial aspirate and plugged telescopic catheter specimens (PTC) with infected cell counts in branchoalv eolar lavage (BAL) specimens for the diagnosis of nosocomial pneumonia. Design: Prospective study of critically ill patients. Setting: intensive care unit in a university hospital. Patients: A total of 64 patients hospitalized for >48 hrs with suspected no socomial pneumonia. Interventions: Fiberoptic bronchoscopy with bronchial aspirate and quantita tive protected specimen brush, PTC, and BAL cultures. PTC and bronchial asp irate specimens were Cram-stained, BAL specimens for infected cell counts w ere examined as described previously in the literature. Measurements and Main Results: Nosocomial pneumonia was diagnosed by the me dical staff based on all available clinical, radiologic, laboratory test, a nd microbiological data and on the course before and after appropriate ther apy. A total of 71% of patients were ventilated, and 70.1% were receiving a ntibiotics. Nosocomial pneumonia was diagnosed in 54% of the cases. On dire ct examination, sensitivity (Se) and specificity (Sp) of bronchial aspirate specimens were Se, 82% and Sp, 60%; of BAL with 5% infected cells, Se, 56% and Sp, 100%; of BAL with 3% infected cells, Se, 74% and Sp, 96%; of PTC s pecimens, Se, 65% and Sp, 76%; and of PTC specimens plus BAL with 3% infect ed cells, Se, 83% and Sp, 78%. BAL with 3% infected cells was significantly better for predicting nosocomial pneumonia than direct examination of bron chial aspirate or PTC specimens (p =.0012). When the BAL showed 3% infected cells, neither direct examination of bronchial aspirate nor direct examina tion of PTC specimens was useful (p = .24 and p = .38, respectively). Combi ned use of direct examination of PTC specimens plus BAL with 3% infected ce lls markedly improved sensitivity, The total cost of each procedure was tak en into account for the final evaluation. Conclusions: Our data suggest that BAL with 3% infected cells is currently the only test whose predictive value for nosocomial pneumonia is sufficient ly high to be of use for guiding the initial choice of antimicrobial class while waiting for quantitative culture results.