OPPORTUNISTIC PNEUMONIA - CLINICO-PATHOLOGICAL STUDY OF 5 CASES CAUSED BY AN UNIDENTIFIED ACID-FAST BACTERIUM

Five patients had opportunistic pulmonary infection caused by acid-fast bacilli, unusual clinical presentations and a unique pathological picture. Clinically, these cases mimicked septic pulmonary emboli or bacterial pneumonia. The infection was temporally related to high-dose corticosteroid therapy, given for renal-transplant rejection in four patients and for therapy of lymphocytic lymphoma in one. Histologic sections of lung-biopsy or autopsy material showed an acute suppurative pneumonia with dense alveolar infiltration by neutrophils, without granuloma formation or caseous necrosis. Predominantly intracellular acid-fast bacilli were present. The organism failed to grow in culture on routine bacterial, fungal and mycobacterial mediums. This unusual and possibly new acid-fast organism is a probable cause of suppurative pneumonia in impaired hosts receiving corticosteroid therapy. (N Engl J Med 301:959–961, 1979) INFECTIOUS complications in patients undergoing renal transplantation and receiving immunosuppressive therapy have been well documented.1 2 3 4 Opportunistic pulmonary infections are frequently difficult to diagnose because of the variety of possible causative agents and the altered host response to the infection. This report describes the clinical, pathological and laboratory findings in five patients with opportunistic pulmonary infection caused by an unusual and possibly new acid-fast bacillus. Patients and Methods Over a three-month period from October to December, 1978, two patients who had undergone renal transplantation were evaluated for fever and pulmonary infiltrates. The acute onset of pulmonary symptoms and altered chest-x-ray findings. © 1979, Massachusetts Medical Society. All rights reserved.