Detection of mycobacteria from blood and bone marrow: a decade of experience

This study reports our experience with methods used at our department from 1981 through 1990 for detection of mycobacteria in blood and bone marrow specimens. Direct inoculation on Lowenstein Jensen media was replaced by Isolator® lysis‐centrifugation followed by inoculation on conventional solid media, and the Bactec 12B and Bactec 13A systems. A total of 3033 specimens were analyzed. A total of 137 mycobacterial isolates were obtained from 42 patients, all HIV‐positive except one. Mycobacteremia caused by M. avium‐intracellulare (83%), M. tuberculosis, M. scrofulaceum and M. kansasii was found. Of 680 blood specimens tested by the last three methods, 7.6% were found to be positive by at least one method and revealed recovery rates of 6.8% for the Isolator®‐solid media system, 3.4% for the Isolator®‐12B system and 6.9% for the 13A system (all isolates MOTT). Mean detection times for 21 cultures found positive by all three methods were 23.6, 23.3 and 17.7 days for the Isolator®‐solid media, Isolator®‐12B and 13A systems, respectively, with a significantly shorter detection time for the 13A system. Low degree (< 1 cfu/ml) mycobacteremia (MOTT) caused delay in the Isolator®‐solid media and the 13A systems and no detection in the Isolator®‐12B system. Antituberculous therapy significantly prolonged the detection times for MOTT in the 13A system in contrast to the other systems.