Blood Media for the Cultivation of Mycobacterium Tuberculosis

Abstract

Human blood media support the growth of minute inocula of tubercle bacilli. In expts. with a standard laboratory strain of tubercle bacillus (H37Rv) and also with other virulent human strains isolated directly from sputum under routine diagnostic conditions, the blood-containing media proved equal to and often superior to 3 standard tuberculosis media from the standpoint of early detection and final amt. of growth. Whenever blood was present in adequate concns. (15-50%), the growth of small inocula of tubercle bacilli regularly occurred, regardless of the basal medium used, the presence or absence of glycerine, egg yolk or a combination of both. Actually, most of these substances showed some inhibition of growth when incorporated into the blood media, particularly when the concn. of blood was below 15%. Fresh defibrinated, citrated, oxalated and even 56-day-old outdated bank bloods were equally effective in supporting the growth from small inocula, but heating the blood caused a slight but definite loss in nutritive value. Preliminary expts. indicate that the blood media may be employed for streptomycin sensitivity tests.