Direct sensitivity test for isoniazid.
Devaki, V.; Mohan, K.; Gangadharam, P.R.J.
Indian Journal of Medical Research; 1969; 57; 1006-1010.
It is well known that the results of isoniazid sensitivity tests by the indirect method have prognostic significance in the treatment of tuberculosis with regimens containing isoniazid (Tuberculosis Chemotherapy Centre, Madras, 1960; Devadatta et al ., 1961), the indirect method is however, complex and time-consuming, and therefore not feasible in institutions with limited facilities.
Direct sensitivity tests are attractive because they involve only one stage of handling (i.e., cultures need not be set up), are simpler and less expensive, and consume less time. Although the direct sensitivity test introduced by Middlebrook and co-workers (Middlebrook and Cohn, 1958: Russell and Middlebrook, 1961) using 7H10 agar medium yielded satisfactory results, it has certain disadvantages. Thus, the medium employed is expensive, the ingredients are not readily available in this country and, in our experience at Madras, losses due to contamination can be considerable.
The paper describes a direct sensitivity test for isoniazid using Lowenstein-Jensen medium, and compares the findings obtained by this method with those obtained by the indirect method.
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