EVALUATING CURRENT METHODS FOR DETERMINATION OF THE SUSCEPTIBILITY OFMYCOBACTERIA TO PYRAZINAMIDE, CONVENTIONAL, RADIOMETRIC BACTEC AND 2 METHODS OF PYRAZINAMIDASE TESTING

The authors compared conventional and Bactec determinations of pyrazin amide susceptibility with pyrazinamidase activity determined using eit her standard Dubos Oleic agar or Middlebrooks 7H9 agar. Of the 26 Myco bacterium tuberculosis tested, Bactec found 16 strains susceptible and 10 resistant, conventional methods found six susceptible and 20 resis tant. Dubos identified 13 and Middlebrooks 10 strains as producing pyr azinamidase (susceptible). Of the 11 strains susceptible in Bactec and resistant by conventional methods, eight produced pyrazinamidase. All mycobacteria other than tuberculosis (6) and Mycobacterium bovis (2) were resistant by all methods. Bactec results gave a better correlatio n with pyrazinamidase results than conventional tests.