An elderly diabetic has left sided orbital cellulitis, CT scan of paranasal sinuses shows evidence of left maxillary sinusitis. A Gram-stained smear of the orbital exudates shows irregularly branching septate hyphae. The following is the most likely aetiological agent.

Ans. is 'a' i.e. AspergillusRef.: Harrison 16th/Ep 1190 (15th/Ep 1178); CMDT 2003 p 1489; Anantnarayan 6th/Ep 577 & 578;Jawetz 22nd/e p554Septate hyphae and involvement of sinuses suggest the diagnosis of Aspergillus infection.Aspergillus can cause sinusitis and the hyphae of Aspergillus are septate and branched.About other options;Mucormycosis -Is an invasive fungal infection caused by a fungus of the species Zygomycetes, therefore, it is also known as Zygomycosis.Diabetes is a predisposing factor for Mucormycosis, but remember that all the fungus of the species Zygomycetes has aseptate hyphae.Fungus of the family Zygomycetes includeRhizopusMucorAbsidiaPilolobusCunninghamellaIn Candida, the infectious form is yeast not hyphae