In confirmation of Fisher's (1952, 1954) results, haemin was found to act as an apparent growth factor for isoniazid-resistant strains of tubercle bacilli and also powerfully to antagonize the action of isoniazid on drug-sensitive organisms. In extension of Fisher's work, these effects of haemin were investigated with drug-sensitive and resistant strains of H37 Rv and B.C.G. The effect of Tween 80 and albumin was also examined. In Fisher's medium when the nitrogen source was changed isoniazid-resistant strains no longer appeared to be haemin-dependent. Middlebrook's observations that isoniazid-resistant tubercle bacilli are deficient in catalase (Middlebrook, 1954) and that catalase enables resistant organisms to grow in a deficient medium (Middlebrook, personal communication) were confirmed. Since the dependence of isoniazid-resistant organisms on haemin or catalase seems itself to be dependent on the presence of asparagine in the medium, it is suggested that haemin has a catalase or peroxidase-like role, and that in the presence of asparagine isoniazid-sensitive organisms can remove peroxide, whereas isoniazid-resistant organisms cannot.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error