Etiology and microbial patterns of pulmonary infiltrates in patients with orthotopic liver transplantation.

STUDY OBJECTIVE To evaluate the etiology and microbial patterns of pulmonary infiltrates in liver transplant patients using a bronchoscopic diagnostic approach and the impact of diagnostic results on antimicrobial treatment decisions. DESIGN A prospective cohort study. SETTING A 1,000-bed tertiary-care university hospital. PATIENTS AND METHODS Fifty consecutive liver transplant patients with 60 episodes of pulmonary infiltrates (33 episodes during mechanical ventilation) were studied using flexible bronchoscopy with protected specimen brush (PSB) and BAL. RESULTS A definite infectious etiology was confirmed in 29 episodes (48%). Eighteen episodes corresponded to probable pneumonia (30%), 10 episodes had noninfectious etiologies (17%), and 3 remained undetermined (5%). Opportunistic infections were the most frequent etiology (16/29, 55%, including 1 mixed etiology). Bacterial infections (mainly Gram-negative) accounted for 14 of 29 episodes (48%), including 1 of mixed etiology. The majority of bacterial pneumonia episodes (n = 10, 71%) occurred in period 1 (1 to 28 days posttransplant) during mechanical ventilation, whereas opportunistic episodes were predominant in periods 2 and 3 (29 to 180 days and > 180 days posttransplant, respectively; n = 14, 82%). Microbial treatment was changed according to diagnostic results in 21 episodes (35%). CONCLUSIONS Microbial patterns in liver transplant patients with pulmonary infiltrates corresponded to nosocomial, mainly Gram-negative bacterial pneumonia in period 1, and to opportunistic infections in period 2 and, to a lesser extent, period 3. A comprehensive diagnostic evaluation including PSB and BAL fluid examination frequently guided specific antimicrobial therapy.