[Accelerated determination of blood bacteriostatic activity in patients with tuberculosis by using the semiliquid...

Blood bacteriostatic activity (BBA) was studied in 87 patients with respiratory tuberculosis. Clinical Mycobacterium tuberculosis (MBT) strains and different culture media, such as solid (Löwenstein-Jensen and Middlebrook), liquid (modified Soton) and semiliquid (SM developed for accelerated determination of drug resistance in MBT) media were used. With isoniazid-resistance of MBT, the use of solid media yielded underestimated BBA. The SM medium based on the Soton medium added by 0.35% of culture agar and 25% equine serum was optimal, which provided evidence for BBA on day 7 (visual recording of MBT growth). Examination of BBA by means of SM revealed a clear inverse correlation between the degree of BBA and the bacteriological parameters of sputum study. The small numbers of sputum MBT cultures (a high correlation, r = -0.88; p = 0.01) and short bacterial isolation (average correlation, r = -0.65; p = 0.01) corresponded to the high values of BBA.