Test Procedures

Sputum and specimens from other sources are concentrated and stained with fluorochrome or Ziehl-Neelsen stain and are cultured for the isolation and identification of mycobacteria. Positive smear results on new patients are reported by fax or phone on the same day. All other smear results are sent by courier or regular mail. New patients with a positive smear receive the Amplified M. tuberculosis Direct Test (MTD) which is performed twice weekly.

When media is positive for growth, cultures are identified by High Pressure Liquid Chromatography (HPLC), DNA Probe (ACCUPROBE), or biochemical testing. Cultures containing pure isolates of mycobacterium may also be submitted for confirmation, identification or susceptibility testing. All M. tuberculosis complex isolates are tested for susceptibility to the following four primary drugs: Isoniazid, Ethambutol, Rifampin, and Pyrazinamide. Additional susceptibility testing for strains of M. tuberculosis complex resistant to the four primary drugs is available. Drug susceptiblity tests on non-tuberculous (NTM) isolates may also be requested. Currently, all confirmation, identification, and susceptibility tests are performed by reference laboratories.

Cultures are incubated for a maximum of six weeks. A report of "no mycobacteria isolated" means that no acid-fast organisms have grown by the end of six weeks. A report of "contaminated" means that there is overgrowth of other bacteria.

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Sterile, leak-proof specimen containers and request slips are available upon request. Follow current shipping regulations. If M. haemophilum or M. genavense is suspected, please contact the TB Lab when specimen is sent: (601) 576-7582.

For questions about collection procedures and how to submit specimens please see the Laboratory Services Guide.

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