Background & objectives: In human immunodeficiency virus (HIV) infected persons with
pulmonary tuberculosis (TB), sputum may not always show acid fast bacilli (AFB). Moreover, in most
cases of suspected extrapulmonary TB (irrespective of HIV status) mycobacteria-containing material is
not readily available for investigation. This study evaluated whether blood culture for Mycobacterium
tuberculosis bacteraemia (mycobacteraemia) help in diagnosing TB in such cases. Methods: A total of
93 consecutive subjects with a clinical diagnosis of tuberculosis with or without laboratory
confirmation, 42 with and 38 without coexisting HIV infection, and 13 patients with HIV infection
without clinical evidence of TB were enrolled. Mycobacterial blood cultures were done using lysis
centrifugation technique followed by subculturing onto the modified Lowenstein-Jenson medium (LJ-1)
and Selective Kirchner's medium followed by subculturing onto the modified Lowenstein- Jenson medium
(LJ-2, LJ-3). Results: Of the 15 (16.2%) subjects with evidence of mycobacteremia in 4 (26.7%) blood
was the first/ only source of diagnosing TB. Among 80 patients with clinical diagnosis of TB whether
supported by laboratory tests or not, 14 (17.5%) had mycobacteraemia. Among the 21 HIV infected
patients with laboratory proven TB, 9 (43%) had mycobacteraemia. Interpretation & conclusion:
Blood culture appears to be a useful additional test to diagnose TB in personss with HIV infection.
In patients without HIV infection, but with clinical picture compatible with TB, blood culture for
mycobacteraemia may occasionally help in the diagnosis. We recommend the use of the lysis
centrifugation technique followed by direct smear of the sediment along with inoculation of the
sediment into both modified Lowenstein-Jenson medium and the Selective Kirchner's medium with
subsequent subculturing onto the modified Lowenstein-Jenson medium for mycobacterial blood culture
for detecting mycobacteraemia