title: Comparison of various measures of sensitivity of M. tuberculosis to ethambutol.
abstract: A sensitivity test for ethambutol was standardised, and performed on cultures isolated from patients before and after the start of chemotherapy with ethambutol and isoniazid. A discrimination type of approach was employed and three criteria of resistance were evolved: (a) growth of 20 colonies or more on ethambutol 4 microgram/ml, using a standard inoculum; (b) a proportion of 25% or more on ethambutol 1.4 microgram/ml; (c) a proportion of 5% or more on ethambutol 2 microgram/ml. The MIC definition appears to be the best in view of its simplicity and insensitivity of the classification (as sensitive or resistant) to variations in inoculum size.
mesh_terms: D004352:Drug Resistance, Microbial; D004977:Ethambutol / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D014376:Tuberculosis / Q000188:drug therapy
chemical_list: D004977:Ethambutol; D007538:Isoniazid