An HIV-positive patient from Manipur presents with fever, weight loss, hepatosplenomegaly and papular skin lesions. Bone marrow smear shows intracellular yeast-like cells dividing by transverse fission with a central transverse septum. Blood cultures on Sabouraud agar show a mould producing a diffusible red pigment. The causative agent is:

• A Talaromyces marneffei ✓
• B Histoplasma capsulatum var. duboisii
• C Penicillium chrysogenum
• D Blastomyces dermatitidis

Explanation

Talaromyces (formerly Penicillium) marneffei is a thermally dimorphic fungus endemic to Southeast Asia and an AIDS-defining pathogen there. In tissue it forms oval yeast cells that divide by fission, leaving a central transverse septum, unlike budding yeasts such as Histoplasma. The red diffusible pigment on culture and fission division are its two hallmark identifiers, and Histoplasma divides by budding, eliminating B.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.