Since pyrazinoic acid formed in bacteria around neutral pH (pH 7.0) is rapidly excreted, pyrazinamide cannot show its effect. For this reason, until now, pyrazinamide susceptibility tests have been performed on media with pH adjusted to 5.5 and 6.0. TK PZA KIT consists of a special growth control medium with efflux pump inhibitor and a pyrazinamide medium with efflux pump inhibitor. In this way, the test can be performed around neutral pH. The strain to be tested is cultured in both media. Growth in the control medium but no growth in the medium with drug indicates that the tuberculosis bacillus is sensitive to pyrazinamide. Growth in both control medium and medium with drug indicates that it is resistant to pyrazinamide.
