Disseminated Salmonellosis in a child with IL12Rß1 deficiency – Case report and review of literature.

Abstract Mendelian susceptibility to mycobacterial disease (MSMD) is a group of genetic disorders characterized by a defect in interferon γ (IFN γ)–mediated immunity, with predisposition to infections caused by atypical and low virulent mycobacteria and other intra-macrophagic organisms like Salmonella, Klebsiella, Listeria etc. A 10-year-old boy, second born of a consanguineously (third-degree) married Indian couple, presented with left inguinal and submandibular lymphadenopathy with low grade fever for 10 days. Past history was significant as the child had been unwell from infancy. At the age of 4 months and 5 years, he was diagnosed to have tubercular axillary lymphadenitis and was treated with anti-tubercular drugs on each occasion and he responded to the same. On examination, he had left submandibular and inguinal lymphadenopathy and mild splenomegaly. Chest radiograph showed enlarged mediastinal nodes. He underwent left inguinal lymph node biopsy that reported granulomatous lymphadenitis. However, culture from the biopsy showed a growth of Salmonella enterica sensitive to ceftriaxone. Genetic evaluation showed pathogenic homozygous mutation c.1791 + 2T > G in exon 15 of IL12Rß1 gene by whole exome sequencing. A diagnosis of Mendelian Susceptibility to Mycobacterial Disease (MSMD) was established and he was treated with intravenous ceftriaxone followed by oral cefixime. He responded promptly and lymphadenopathy resolved. He is currently being maintained on azithromycin prophylaxis. Children and adults presenting with disseminated infections with atypical mycobacteria and salmonella must be evaluated for MSMD. Disseminated salmonellosis is a peculiar manifestation in IL12Rß1 deficiency. A detailed review of literature on IL12RB1 deficiency was performed. Index case has been discussed in light of the previously published literature.