Mycobacterium tuberculosis Susceptibility, Broth Dilution and Confirmation

Mycobacterium tuberculosis isolated from a primary clinical specimen, on a submitted AFB conventional solid medium, and a bacterial swab inoculated with isolated colonies from a pure culture or an AFB broth medium.

Pure culture isolate on an AFB conventional solid medium and a bacterial swab inoculated with isolated colonies from a pure culture, or a minimum of 1 mL of AFB broth medium.

Conventional or broth medium, tightly sealed, in etiologic agent packaging.

Determine the susceptibility of Mycobacterium tuberculosis to a profile of antimycobacterial agents.

Susceptibilities cannot be reported if the organism fails to grow in the test medium. Susceptibilities cannot be performed on mixed cultures.

Broth-based and conventional method.

Susceptibilities should be performed on the first organism isolated from a patient, and at one and three-month intervals if that organism continues to be isolated while the patient is on therapy. Susceptibility tests should be performed in patients with recurrent tuberculosis, as resistant strains are common in recurrent infection. Outbreaks have occurred in health care workers, prison inmates, and prison employees.^1,2 Failure to take all drugs in a multidrug regimen can lead to a shift toward resistant organisms and treatment failure. Nontuberculosis Mycobacteria, particularly strains of the M avium complex, are resistant to those drugs used for therapy of M tuberculosis.³

Susceptibilities will be performed based on state regulations and/or statutes. Many states require first isolates of M tuberculosis at an institution to be tested.