Mycobacterium – Corneal scrapings

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit


Corneal scraping


MGIT tube, 2 LJ slants and a slide – provided as needed by PHO Laboratory

Submission and Collection Notes


Prior to collecting the specimen contact Public Health Ontario laboratory to obtain the MGIT tube, 2 LJ slants and a slide.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Place specimen container(s) in the biohazard bag and seal bag, and insert the completed requisition in the pocket on the outside of the sealed biohazard bag.

Store at 2-8 °C if transport is delayed more than one hour. Specimens should be transferred to the lab ASAP.

Special Instructions

Corneal scraping: Scrapings are obtained by the physician. A MGIT tube and 2 Lowenstein Jensen slants are directly inoculated. A smear is also made and placed in the slide holder for safe transportation. Return the slide and inoculated cultures to the Public Health Laboratory ASAP.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Mycobacterium cultures are performed daily Monday to Saturday. 

The turnaround time for smear results is up to 1 day.

The turnaround time for negative cultures is 49 days.

A positive culture is reported within 24 hours of growth. Depending on the species and treatment of the patient, a culture may grow within 1 to 2 weeks or take as long as 6-7 weeks.

All new isolates of M. tuberculosis complex are phoned to the submitter within 24 hours of identification.

Test Methods

The smear, is stained using the Auramine-Rhodamine (AR) fluorochrome stain. Acid Fast Bacilli are visualized using fluorescence microscopy.

A negative AFB smear does not rule out TB, the culture may still be positive.

The MGIT and LJ slants are incubated for up to 7 weeks.


Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that have smear positive for Acid Fast Bacilli are to be reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Unacceptable specimens

Any samples submitted by a method other than indicated above.

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Laboratory Services

Updated 20 July 2020