The investigation of the effectiveness of TK medium in determining primary anti-tuberculosis drug susceptibilities of Mycobacterium tuberculosis and a newly developed pyrazinamide susceptibility test

Abstract

Background and Aim: The rapid and reliable detection of primary drug susceptibility tests for Mycobacterium tuberculosis is crucial for effective treatment and monitoring drug resistance. This study aims to investigate the effectiveness of the TK Anti TB PNB Kit and newly developed TK PZA Kit (TiBO, Türkiye), both prepared with the colorimetric TK medium, in determining drug susceptibility against primary anti-tuberculosis drugs (isoniazid, ethambutol, rifampicin, streptomycin and pyrazinamide). METHODS: The primary anti-tuberculosis drug susceptibilities of 13 M. tuberculosis quality control strains (INSTAND, Germany) were tested according to manufacturer instructions, using the TK Anti TB PNB kit and TK PZA kit. The tubes were incubated at 37°C in automated Mycolor TK device (TiBO, Türkiye). RESULTS: The growth of all strains was inhibited in the medium containing PNB, indicating that they are M. tuberculosis complex group (Figure 1). In test tubes, a yellow color change signified resistance, whereas the absence of color change signified susceptibility to the tested antibiotic (Figure1, Figure 2).Sensitivity of TK Anti TB PNB and TK PZA Kits were found to be 100% and 77% concordant, respectively, as compared to the susceptibility results of quality control strains reported by INSTAND (Table 1). CONCLUSIONS: The ready-to-use drug-containing tubes of TK Anti-TB PNB and TK PZA kits prevent preparation errors and contamination. There are usually more errors in PZA testing when rapid culture systems are used. TK PZA Kit provided promising results for PZA susceptibility testing. To eliminate discordant results of PZA susceptibility, breakpoint drug concentrations should further be studied.

Keywords

• {Mycobacterium tuberculosis}
• tuberculosis
• TK Anti-TB PNB
• TK PZA