Improved method for testing susceptibility of Mycobacterium tuberculosis to pyrazinamide.
The acid medium required to test susceptibility of Mycobacterium tuberculosis to pyrazinamide (PZA) is a major problem in obtaining reliable test results. Satisfactory growth is usually obtained on Middlebrook and Cohn 7H10 medium at pH 5.5 if albumin-dextrose-catalase (ADC) supplement rather than oleic acid-albumin-dextrose-catalase is used; however, some lots of ADC supplement still fail to support growth at this low pH. A rapid turbidimetric test was developed to determine the growth-supporting potential of ADC enrichment for M. tuberculosis at pH 5.5. An atmosphere supplemented with 5 to 10% carbon dioxide, used to stimulate growth of tubercle bacilli on 7H10 medium, counteracted the growth-inhibiting effects of PZA. By using optimum conditions of medium and pH, the susceptibility of 90% of M. tuberculosis strains to PZA was determined.
D001412:Bacillus subtilis / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D019301:Oleic Acid; D009829:Oleic Acids; D011718:Pyrazinamide / Q000494:pharmacology*
D003470:Culture Media; D009829:Oleic Acids; D002245:Carbon Dioxide; D011718:Pyrazinamide; D019301:Oleic Acid