Aetiology of pulmonary diseases in immunocompromised patients.

Fibreoptic bronchoscopy with bronchoalveolar lavage (BAL), transbronchial lung biopsy (TBB) and brushing was performed, in 134 episodes of pulmonary disease in 118 compromised patients. Sixty eight of the patients were infected with immunodeficiency virus type 1 (HIV-1), 18 were renal and pancreas transplant recipients, 7 were liver and 15 were bone marrow transplant recipients, and 10 patients were undergoing immunosuppressive and/or cytotoxic drug therapy. Pneumocystis carinii (PC) was the predominant pathogen in HIV-1 infected patients. It was considered to be the aetiological cause of pneumonia in 54/82 (66%) episodes of lung complications noted in these patients. Cytomegalovirus (CMV) was the most common micro-organism in transplant recipients. CMV pneumonia was diagnosed in 22/42 episodes of pulmonary disease in these patients. CMV was detected by bronchoscopy procedures at a relatively high frequency of 36/82 (44%) episodes in HIV-1 infected patients. However, after analysis of clinical information, cultures from leucocytes and autopsy findings, CMV seemed to be involved in the pathogenicity of pneumonia in only two out of the 36 patients. Bacterial aetiology, including mycobacterial agents, was unusual, but was the major cause of pulmonary infections in 6/10 episodes in patients undergoing extensive immunosuppressive and/or cytotoxic drug therapy. Bronchoscopy was helpful in establishing correct aetiology in 98/134 (73%) episodes of pulmonary disease. Growth of Candida albicans and bacteria should always be viewed sceptically because of the possibility of contamination from colonization in the upper respiratory tract.