Pulmonary infiltrates in non-HIV immunocompromised patients: a diagnostic approach using non-invasive and bronchoscopic procedures

Background-The development of pulmonary infiltrates is a frequent life thre atening complication in immunocompromised patients, requiring early diagnos is and specific treatment. In the present study non-invasive and bronchosco pic diagnostic techniques were applied in patients with different non-HIV i mmunocompromised conditions to determine the aetiology of the pulmonary inf iltrates and to evaluate the impact of these methods on therapeutic decisio ns and outcome in this population. Methods-The non-invasive diagnostic methods included serological tests, blo od antigen detection, and blood, nasopharyngeal wash (NPW), sputum and trac heobronchial aspirate (TBAS) cultures. Bronchoscopic techniques included fi brobronchial aspirate (FBAS), protected specimen brush (PSB), and bronchoal veolar lavage (BAL). Two hundred consecutive episodes of pulmonary infiltra tes were prospectively evaluated during a 30 month period in 52 solid organ transplant recipients, 53 haematopoietic stem cell transplant (HSCT) recip ients, 68 patients with haematological malignancies, and 27 patients requir ing chronic treatment with corticosteroids and/or immunosuppressive drugs. Results-An aetiological diagnosis was obtained in 162 (81%) of the 200 pati ents. The aetiology of the pulmonary infiltrates was infectious in 125 (77% ) and noninfectious in 37 (23%); 38 (19%) remained undiagnosed. The main in fectious aetiologies were bacterial (48/125, 24%), fungal (33/125, 17%), an d viral (20/125, 10%), and the most frequent pathogens were Aspergillus fum igatus (n=29), Staphylococcus aureus (n=17), and Pseudomonas aeruginosa (n= 12). Among the noninfectious aetiologies, pulmonary oedema (16/37, 43%) and diffuse alveolar haemorrhage (10/37, 27%) were the most common causes. Non -invasive techniques led to the diagnosis of pulmonary infiltrates in 41% o f the cases in which they were used; specifically, the diagnostic yield of blood cultures was 30/191 (16%); sputum cultures 27/88 (31%); NPW 9/50 (18% ); and TEAS 35/55 (65%). Bronchoscopic techniques led to the diagnosis of p ulmonary infiltrates in 59% of the cases in which they were used: FBAS 16/2 8 (57%), BAL 68/135 (51%), and PSB 30/125 (24%). The results obtained with the different techniques led to a change in antibiotic treatment in 93 case s (45%). Although changes in treatment did not have an impact on the overal l mortality, patients with pulmonary infiltrates of an infectious aetiology in whom the change was made during the first 7 days had a better outcome ( 29% mortality) than those in whom treatment was changed later (71% mortalit y; p=0.001). Conclusions Non-invasive and bronchoscopic procedures are useful techniques for the diagnosis of pulmonary infiltrates in immunocompromised patients. Bronchial aspirates (FBAS and TEAS) and BAL have the highest diagnostic yie ld and impact on therapeutic decisions.