Pulmonary Atypical Mycobacterial Infection in a Child with Severe Combined Immune Deficiency

Abstract

Mycobacterium avium intracellulare (MAI) infection has not been reported in patients with severe combined immunodeficiency (SCID) prior to immune reconstitution despite the predisposition to opportunistic infection and defective cell mediated immunity in these patients. We report a case of an infant with X-linked SCID (interleukin- [IL-2] receptor γ chain defect), who at age 9 months developed fever, hypoxia, and worsening bilateral pulmonary infiltrates 2 days after receipt of a maternal graft of cytokine-mobilized peripheral blood stem cells enriched for CD34⁺ cells and depleted of CD3⁺ cells. Bronchoalveolar lavage (BAL) specimen was positive on acid-fast bacilli (AFB) culture by radiometric method, and DNA probe confirmed the presence of MAI. After 4 months of treatment with azithromycin, rifabutin, and ethambutol, the patient had radiographic and clinical improvement and negative BAL for AFB by smear and culture. SCID patients with prolonged lower respiratory symptoms, hypoxia, abnormal radiographs, failure to isolate specific pathogens, and poor response to standard antimicrobial regimens should be evaluated for infection with MAI.