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

Study objective: To evaluate the etiology and microbial patterns of pulmona ry infiltrates in liver transplant patients using a bronchoscopic diagnosti c 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 e pisodes of pulmonary infiltrates (33 episodes during: mechanical ventilatio n) were studied using flexible bronchoscopy with protected specimen blush ( PSB) and BAL. Results: A definite infectious etiology was confirmed in 29 episodes (48%). Eighteen episodes corresponded to probable pneumonia (30%), 10 episodes ha d noninfectious etiologies (17%), and 3 remained undetermined (5%). Opportu nistic 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 bac terial pneumonia episodes (n = 10, 71%) occurred in period 1 (1 to 28 days posttransplant) during mechanical ventilation, whereas opportunistic episod es were predominant in periods 2 and 3 (29 to 180 days and > 180 days postt ransplant, respectively; n = 14, 82%). Microbial treatment was changed acco rding to diagnostic results in 21 episodes (35%). Conclusions: Microbial patterns in liver transplant patients with pulmonary infiltrates corresponded to nosocomial, mainly Gram-negative bacterial pne umonia in period 1, and to opportunistic infections in period 2 and, to a l esser extent, period 3. A comprehensive diagnostic evaluation including PSB and BAL fluid examination frequently guided specific antimicrobial therapy .