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

Ans. is 'a' i.e., Aspergillus(Ref: Harrison, 18th/e, p. 1655, 1656 and 17th/e, p. 1251)* Septate hyphae and involvement of sinuses suggests the diagnosis of Aspergillus infection.* Aspergillus can cause sinusitis and the hyphae of Aspergillus are septate and branched.