Susceptibility to mycobacterial infections due to interferon-gamma and interleukin-12 pathway defects.

A case of interferon-gamma (IFN-gamma)/interleukin-12 (IL-12) pathway defect is presented. Pathophysiology, clinical characteristics, diagnostic test, and case management are reviewed. Clinical Pearls and Pitfalls include: (1) A high probability of a defect in the IFN-gamma/IL-12 cascade exists in patients with disseminated or recurrent infection due to poorly pathogenic mycobacteria or systemic infections caused by non-typhi Salmonella species that are persistent and recurrent despite antibiotic therapy. (2) Although less frequent, patients with impaired IFN-gamma/IL-12 mediated immunity are more susceptible to cytomegalovirus, human herpesvirus 8, herpes simplex virus, Listeria monocytogenes, and Histoplasma capsulatum.