DR.K.PRAGATHI ASSISTANT PROFESSOR

DEPARTMENT OF MICROBIOLOGY KIMS,NARKETPALLY.

DEFINITION: Inflammation of cornea that results from infection by a fungal organism. Serious cause of ocular morbidity.

Early diagnosis and treatment is necessary to

prevent further complications.

More common in tropics and sub-tropics.

Local : Ocular trauma with vegetable matter. Surgical trauma - LASIK, - Photorefractive Keratectomy. Contact lens. Dry eye . Topical steroids

Diabetes mellitus. Malnutrition. Alcoholism. HIV.

World wide - Aspergillus species (MC ) .

India : - Aspergillus - Fusarium - Penicillium - Candida (rare)

FILAMENTOUS FUNGI YEAST LIKE ORGANISMS

HYALINE FUNGI PHAEOID FUNGI

(Pigmented )

A.Hyaline Fungi : - Aspergillus fumigatus,A.flavus Fusarium solani,F.oxysporum Acremonium species Paecilomyces species Penicillium species Pseudallescheria boydii.

Curvularia sp. Bipolaris sp. Alternaria sp. Exserohilum sp. Cladosporium. Aureobasidium pullulans.

Yeast-like Fungi : Candida albicans. Canida tropicalis. Candida krusei.

Specimen collection : Corneal scrapings - Slit lamp examination Margin and base of ulcer. Aseptic technique. Local anaesthetic (4% xylocaine drops ) . Surgical blade/Kimuras spatula. Corneal Biopsy . Calcium alginate swabs .

DIRECT EXAMINATION

Gram Stain

10% KOH

Calcofluor white

Giemsa stain

Grocott methenamine silver stain.

DIRECT EXAMINATION

2 SETS OF SDA WITH ANTIBIOTICS ( 25 and 37 degree C)

1 SET OF BHI AGAR ( 37 degrees C)

BLOOD AGAR ( 37 degrees C)

INOCULATION :

C or S shaped streaks . Ensures growth is from inoculum and not a contaminant.

Cultures are checked every day – 1st week. Twice a week thereafter. Most fungi grow in 24 hrs – 2 weeks. Cultures are declared negative only after 3 weeks.

Positive cultures from 2 or more sets is convincing.

Mycelial isolates identified by – Colony morphology. - LCB mount. - Slide cultures.

ASPERGILLUS

A.Niger

SDA

A.Nidulans

A.fumigatus

GROWTH ON SDA LCB MOUNT

GROWTH LCB MOUNT

GROWTH ON SDA

Identification tests - Germ tube. - Reduction of tetrazolium medium. - Chlamydospores production. - Urease test. - Sugar fermentation . - Sugar assimilation.

GROWTH ON SDA GRAM STAIN

Molecular techniques : PCR.

Confocal Microscopy - Non invasive. - Invivo technique. - Identifies both hyphal and yeast forms.

THANK YOU