Aspergillosis in 25 renal transplant patients. Epidemiology, clinical presentation, diagnosis, and management

Abstract

In immunocompromised renal transplant patients, aspergillosis can be a life-threatening opportunistic infection. During an 8-year period, 25 renal transplant recipients at the University of Minnesota Hospitals developed unequivocal invasive aspergillosis that occurred in epidemic-like patterns in immunocompromised patients throughout the hospital. The premortem diagnosis was made in only 14 of the 25 patients. Seventeen patients died, and three of the eight survivors lost their allografts. The prognosis was dependent upon the clinical pattern of illness: three clinical patterns emerged: (1) cavitary lung disease, (2) diffuse pulmonary disease, and (3) central nervous system disease. All patients in the latter two categories died. The best results were with those patients treated with both amphotericin B and excision of cavitary lung lesions. All three patients treated in this manner survived with functioning grafts. Traditionally, sputum cultures have been thought to be unreliable because Aspergillus is a common colonizer of the upper respiratory tract and a contaminant in laboratories. In this study, false positive sputum cultures were common. A positive sputum culture can be helpful, however, all patients with two positive sputum cultures proved to have invasive aspergillosis. In addition, 86% of patients with positive sputum cultures who were clinically ill proved to have invasive infection. Bronchoscopy is a useful technique to follow up a positive sputum culture or investigate negative sputum cultures with typical clinical patterns. Routine bronchoscopy, unfortunately, also yields a high incidence of false positive cultures. Since the use of covered brush bronchoscopy technique, however, no false positive transbronchial cultures have been found. Transbronchial biopsy is a useful adjunct and is proof of the presence of invasive disease when the results are positive. However, false negative results are also found. Overall, the highest diagnostic yield is obtained both with transbronchial lung biopsy and covered brush bronchoscopy culture. All eight patients with both these procedures were correctly identified as having invasive pulmonary aspergillosis.