Recurrent Talaromyces Marneffei Infection Revealing X-Linked Hyper IgM Syndrome in an HIV-Negative Infant: A Diagnostic and Therapeutic Challenge.

Talaromyces marneffei (TM), a temperature-dependent dimorphic fungus and opportunistic pathogen, poses a significant threat to immunocompromised individuals, particularly in Southeast Asian regions such as China and India. This case report details an 8-month-old HIV negative Chinese infant with recurrent cough and fever, who was diagnosed with TM infection through blood culture and metagenomic next-generation sequencing (mNGS). Additionally, whole exome sequencing identified a point mutation (c.346+1G>T) in the child's CD40LG gene, primary immunodeficiency calized to chromosome position chrX:135736590, leading to X-linked Hyper IgM Syndrome (XHIGM). The patient was managed with intravenous immunoglobulin (IVIG) and a 12-day course of amphotericin B and itraconazole, which led to significant clinical improvement and discharge on a quarterly IVIG regimen. However, he required readmission for recurrent TM pneumonia at 9 and 40 months post-discharge. This case highlights the diagnostic challenge and management complexity of TM infection in the context of primary immunodeficiency.