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

Infection caused by inhalation of the Aspergillus conidia or mycelial fragments resulting in respiratory diseases, disseminated aspergillosis in brain, kidney and hea.and superficial infection like sinusitis, mycotic keratitis and otomycosis. Sinusitis is caused by A.flavus and A.fumigatus On microscopy, it shows non pigmented septate hyphae with characteristic dichotomous branching at an angle of approximately 45 degrees. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition .