Impact of graft colonization with gram-negative bacteria after lung transplantation on the development of bronchiolitis obliterans syndrome in recipients with cystic fibrosis.

Bronchiolitis obliterans syndrome (BOS) represents the leading cause of late mortality after lung transplantation (LTx). Cystic fibrosis (CF) patients frequently show airway colonization with gram-negative bacteria (GNB) both before and after LTx. Graft colonization with GNB and its relevance towards BOS development were investigated in a CF population after LTx. Adult CF patients receiving LTx and surviving at least 6 months were included in this prospective observational study between 1/1/2002 and 30/6/2006 in a single center and followed until 31/3/2007. Pre- and post-LTx respiratory culture samples were compared for the presence of identical GNB. BOS-free survival was compared in colonized and non-colonized patients. Fifty-nine adult CF patients with a median age at LTx of 25.5 (18-49) years were included and had a median follow-up of 966 (128-1889) days. Seven patients (15%) demonstrated immediate eradication of GNB in lower respiratory tract samples. A further 18 patients (34%) demonstrated transient colonization. Thirty-four recipients had further positive samples after LTx. Eighteen patients (31%) developed BOS >or=stage 1, 508 (114-1167) days after LTx. Freedom of graft colonization with pseudomonads was independently associated with less frequent development of BOS (p=0.006). Persistent graft colonization with pseudomonads increases the prevalence of BOS after LTx in CF patients. A significant proportion of post-LTx CF patients demonstrates subsequent GNB eradication during later follow-up and this may have a protective role against development of BOS. Strategies to eradicate airway colonization or reduce bacterial load may prevent BOS in CF patients after LTx.