Mycobacterium tuberculosis (TB) – drug resistance testing

Alternative Names/Synonyms	Antimicrobial susceptibility testing of Mycobacterium tuberculosis isolates
Laboratory	Microbiology
Sub-section	Bacteriology
Specimen Type	○ Any specimen submitted for Mycobacterial culture that grows Mycobacterium tuberculosis

Other Information

○ First positive TB culture from a patient is tested routinely for susceptibility to first-line agents rifampin, isoniazid, pyrazinamide, ethambutol. Repeat positive cultures (at least 3 months following the first positive specimen) will be tested

○ Isolates resistant to rifampin or any two first-line antimicrobials are also tested for susceptibility to amikacin, capreomycin, ethionamide, kanamycin, linezolid, moxifloxacin, ofloxacin, PAS, rifabutin and streptomycin
○ In the case of resistance to PZA, testing to determine whether the strain is M. bovis or M. bovis BCG will automatically be performed.

Sample Stability

Refer to section Sample Processing / Delivery

Referral Laboratory

PHOL to NML

Routine Turnaround Time

○ 1st line susceptibility testing: up to 12 days from the date of the culture report
○ 2nd line susceptibility testing: up to 12 days after the 1st line results are reported
○ WGS: 20 days from the date of specimen receipt at NML

Laboratory Contact Information

416-586-4800 extension 4574

Approval Required

Sample Processing / Delivery

○ The specimen will be referred to the Public Health Ontario Laboratory for testing. Positive cultures can be referred to the National Microbiology Laboratory/National Reference Centre for Mycobacteriology for molecular antimicrobial resistance prediction.