Corneal Scrapings

Corneal scrapings are collected for the diagnosis of keratitis (inflammation of the cornea) caused by bacterial, fungal, viral, chlamydial or acanthamoeba infection.

The physician usually prepares two or three slides and inoculates the appropriate media at the time of specimen collection. The following media is to be supplied to the physician for each eye: BA, CHOC, SABHI-C. The physician will inoculate the plates in rows of “C” – shaped marks, with each row representing a separate sample.

If a delay in transport or processing is anticipated, the specimen should be kept in the incubator (35°C).

Virus and chlamydia detection require universal transport media (UTM).

If acanthamoeba is requested, recommend collection of specimen into approximately 2 mL sterile water and forward specimen to PHL for processing. Also request the contact lens case and contact lens solution in original container to be submitted. If there is a delay in transport, store the specimen at room temperature.

Setup If pre-inoculated plates are received and no smear or additional specimen is received, direct smear stains will not be performed.

Direct Examination

Gram stain KOH Calcofluor white stain (if two smears are provided).

Culture

Media Incubation
Blood Agar (BA) CO2, 35°C x 48 hours
Chocolate Agar (CHOC) CO2, 35°C x 48 hours
SABHI with Chloramphenicol (SABHI-C) O2, 30°C x 4 weeks

Interpretation Examine the culture plates daily.

All organisms should be identified. If a mixture of organisms is present consult with charge technologist or microbiologist.

Reporting

Gram stain

Report, without quantitation, the presence of pus cells and organisms.

Culture

Negative report
“No growth.”

Positive
Report all isolates with appropriate susceptibilities without quantitation.

References H.D. Isenberg. 2004. Specimen Collection, Transport and Acceptability p. 2.1.1 – 2.1.28. In Clinical Microbiology Procedures handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.

H.D. Isenberg, 2004. Wound Cultures – Wound and Soft Tissue Cultures, p. 3.13.1.1 – 3.13.1.16. In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.

H.D. Isenberg. 2004. Ocular Cultures p. 3.10.1. – 3.10.8. In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.