Comparative study on the use of solid media: Löwenstein-Jensen and Ogawa in the determination of anti-tuberculosis drug susceptibility.

A total of 53 Mycobacterium tuberculosis strains were examined to evaluate the consistency of susceptibility tests using two solid egg-based culture media, Ogawa and Löwenstein-Jensen (L-J), in order to assess the inter-media differences in susceptibility tests for anti-tuberculosis drugs. Fifty-three M. tuberculosis strains were tested for resistance against isoniazid, rifampicin, ethambutol, streptomycin and other alternative drugs on L-J and Ogawa media. Data from isoniazid (INH) revealed 31 strains were susceptible and 11 strains were resistant in L-J medium. On the other hand, one strain showed resistance against INH only on Ogawa medium. This gave a consistency ratio of 97.7% for INH between these two media. Similarly, the methods had 100% compatibility with rifampicin, 86.0% with ethambutol and 88.4% with streptomycin. When 41 of these strains were tested against ethionamide, enviomycin, para -aminosalicylate, sparfloxacin, and levofloxacin, the same numbers of strains were shown to be resistant or susceptible to L-J and Ogawa media. Similarly, the consistency ratio was 75.6% for kanamycin and 61.0% for capreomycin. There are inconsistencies between results obtained with L-J and Ogawa media, Ogawa medium had a tendency to produce results that indicated more resistant strains. However, the differences were statistically negligible.