The main focus of our work in the Mycobacteriology Laboratory is to provide testing to aid in the diagnosis and control of TB in the State of Maryland. As a secondary goal, our lab also acts as a reference lab, assisting area hospital labs in the identification of a wide range of mycobacterial species.
Testing offered Monday through Friday includes:
§ Culture and Smear: We process a wide range of clinical specimens for AFB smear and culture. All smears are read by Fluorochrome staining with positives confirmed by Zhiel-Neelsen. Culture is performed in both MGIT broth and Lowenstein-Jensen slants and held for eight (8) weeks incubation.
§ Culture Identification: All mycobacterial species isolated are identified to the best of our ability. We utilize DNA probes for the rapid identification of M. tb complex, M. avium complex, M. gordonae, and M. Kansasii.
§ Drug Susceptibility Testing: All new TB isolates are tested against the first line drugs for resistance in the MGIT system. The second line drugs are also tested by agar proportion in the case of resistant isolates.
§ Nucleic Acid Amplification Testing: Sputum samples can be tested directly for M. tb complex, with results available the same day the specimen is processed. This assay is performed on all first smear-positive specimens, as well as smear-negative specimens under specific circumstances by direct request.
§ TB Genotyping: By law, all new isolates of M. tb complex must be referred to our laboratory to be sent for genotyping.
§ Quantiferon TB-Gold In-Tube: An Interferon-Gamma Release Assay (IGRA) by which latent TB infection can be detected in blood specimens. This test is especially useful in foreign-born populations in which BCG vaccination could cross react with Tuberculin Skin Tests (TSTs). This assay is offered on a limited basis through county health departments.