Further Experience with a New Blood Medium for the Cultivation of Mycobacterium tuberculosis

Abstract

In the study described it was demonstrated that a modified blood medium containing plain agar, glycerol, outdated human bank blood, and penicillin was satisfactory for the cultivation of tubercle bacilli under routine diagnostic conditions. In comparison with the Lowenstein-Jensen medium it was found that the number of positive cultures obtained and the average time of first appearance of growth were slightly better on the blood than on the Lowenstein-Jensen medium. The number of tubes contaminated was much less for the former than the latter medium, which is attributed to the penicillin. The chief advantages of the blood medium are economy, simplicity of preparation, and ability to grow tubercle bacilli from small inoculums, easily, recognizably, and in a short time. The ingredients are readily obtainable and fresh mediums can be prepared in a few minutes. Refrigerated mediums have proved exceedingly stable in tightly sealed screw-cap tubes for as long as 4 months. All these factors should encourage a wider use of cultural methods for the bacteriologic diagnosis of tuberculosis.