While setting up culture for suspected dermatophytosis from a skin scraping, cycloheximide is added to Sabouraud dextrose agar. What is the purpose of this additive?

• A To inhibit bacterial contaminants
• B To inhibit rapidly growing saprophytic fungi ✓
• C To enhance pigment production by dermatophytes
• D To induce formation of macroconidia

Explanation

Cycloheximide suppresses fast-growing saprophytic moulds such as Aspergillus and Penicillium that would otherwise overgrow the slower dermatophytes on the plate. Chloramphenicol or gentamicin is the additive used to prevent bacterial contamination, so option A describes the other standard supplement to mycological media. Neither additive induces conidiation or enhances pigment production, which depends on the species and medium composition itself.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 12th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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