Which pair correctly matches a dermatophyte genus with its characteristic macroconidial morphology on lactophenol cotton blue preparation?
- A Trichophyton: abundant smooth-walled, club-shaped macroconidia in clusters
- B Microsporum: numerous, thick-walled, spindle-shaped macroconidia ✓
- C Epidermophyton: numerous thin-walled, pencil-shaped macroconidia
- D Trichophyton: macroconidia absent, microconidia never produced
Explanation
Microsporum characteristically produces many rough, thick-walled, spindle-shaped macroconidia. Epidermophyton produces smooth-walled, club-shaped macroconidia in clusters and lacks microconidia entirely, so option A actually describes Epidermophyton. Trichophyton produces thin-walled, cylindrical or pencil-shaped macroconidia along with abundant microconidia, so option C misassigns Trichophyton features and option D is false because Trichophyton is defined partly by its plentiful microconidia. These macroconidial differences are the basis of laboratory speciation of dermatophytes.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.