Mycobacteriology (TB) Laboratory: Testing
Isolation of Mycobacteria
Mycobacteria can be isolated from many sources, including respiratory specimens, blood specimens, CSF, aspirates, tissue, and autopsy specimens from humans and animals. The standard digestion, decontamination, and concentration procedure is followed in the laboratory to maximize the recovery of mycobacteria from specimens. A fluorescent smear is performed on all specimens, except blood, feces, and urine, to determine whether the specimen contains acid-fast bacilli (AFB) and to make an approximate assessment of the bacterial load. To further maximize recovery of mycobacteria, processed specimens are cultivated in four types of media: BACTEC 460 7H12 broth, Middlebrook 7H11plain and selective agar, and Lowenstein-Jensen.
Mycobacteria may be isolated from specimens and the viable bacteria can be quantified as number of colony forming units per ml of specimen (CFU/ml). Quantitative assessment of the bacterial load in the patient's specimens over the course of therapy can be used as an indicator of the patient's therapeutic response.
Testing Methods
Rapid methods of
mycobacterial species identification and drug susceptibility testing
are used to assure timely detection of drug-resistant tuberculosis
cases.
- Smear examination results are reported within twenty-four hours,
- Detection and identification of M. tuberculosis within two weeks for 80 percent of specimens,
- Drug-susceptibility test results within three weeks for 75 percent of specimens submitted.
- Open seven days a week to assure the timeliness of these analyses.
Learn more about some of our testing methods:
Find information about requisitions and specimen handling.
