Major infection of ear:

 i) acute otitis media

ii) Chronic suppurative otits media

iii) otitis externa

Causative organisms: S. pyogens, H. influenzae, Moraxellacatarrhalis, M. pneumoniae, P. aeruginosa, S. aureus, coliform bacilli

Mode of infection:

-Organisms spreads to middle ear via the Eustachian tube from Nasopharynx,

-As long as eardrum remains intact, infected exudates cant be collected in the swabs

-In such case throat swab may give provisional diagnosis

Specimen: swabs taken from external auditary meatus

Transport media: Amies charcoal transport media


: take two swabs if possible, one for culture and next for gram stain

-Nature of organisms in gram stain gives presumptive idea of causative agents

-Culture aerobically on MA and BA plates and SDA for fungal growth

  • On SDA place 50 unit disc of Nystatin and incubate at 35-37°C for Candidia and at 28°C for Aspergillus
  • On plates observe for the colony characteristics and perform different biochemical tests and identify the organism
  • For fungi perform lactophenol cotton blue cellophane tape method to observe the fungal spores
  • For Candida, Gram staining and Germ tube test: +ve


– Coagulase negative staphylococci, Diptheroid bacilli

– Should be ignored.

Treatment: Amoxycillin, Amoxy Clav, Erythromycin, Ofloxacin

Binod G C

I'm Binod G C (MSc), a PhD candidate in cell and molecular biology who works as a biology educator and enjoys scientific blogging. My proclivity for blogging is intended to make notes and study materials more accessible to students.

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