Author(s)

Fatima Osman¹, Farzana Ismail^1,2, Ayman Osman³, Shaheed Omar⁴, Halima Said⁴, Nazir Ismail⁴

¹Department of Medical Microbiology, Faculty of Health Science, University of Pretoria, Pretoria, South Africa.
²National Health Laboratory Service, Tshwane Academic Division, Pretoria, South Africa.
³Department of Immunology, Faculty of Health Science, University of Pretoria, Pretoria, South Africa.
⁴Centre for Tuberculosis, National Institute for Communicable Diseases, Johannesburg, South Africa.

Background: Pyrazinamide (PZA) is one of the most important drugs for tuberculosis (TB) treatment, however, its susceptibility is not routinely tested. High-resolution melting (HRM) curve analysis has been widely used for many applications. In this study, HRM assay was developed and evaluated for the detection of PZA resistance in Mycobacterium tuberculosis clinical isolates. Methods: Ninety five M. tuberculosis clinical isolates with different susceptibility patterns to anti-TB drugs were used to evaluate this assay. Isolates were phenotypically (Bactec MGIT 960) and genotypically (HRM and pncA gene sequencing) analysed for PZA resistance. Results: Bactec MGIT 960 analysis revealed that 29 of the 95 M. tuberculosis isolates were PZA resistant. In comparison to the Bactec MGIT 960, HRM showed a sensitivity of 47.7% and specificity of 74.6%, and the overall agreement between the two methods was 68.4%. Based on DNA sequencing, a correlation of 0.67 (significant at p-value < 0.05) between phenotypic resistance to PZA and pncA mutations was observed. PZA resistance was strongly associated with multi-drug resistant (MDR)-TB as it was shown in 79.3% of the MDR isolates included in the study. Conclusion: HRM is simple and useful for screening clinical M. tuberculosis isolates for PZA resistance, however, further modifications to improve its performance are required.

Pyrazinamide, Tuberculosis, High Resolution Melting Curve Analysis, Drug Resistance, pncA Gene

Osman, F. , Ismail, F. , Osman, A. , Omar, S. , Said, H. and Ismail, N. (2016) High Resolution Melting Curve Analysis for Rapid Detection of Pyrazinamide Resistance in Mycobacterium tuberculosis Clinical Isolates. Journal of Tuberculosis Research, 4, 155-172. doi: 10.4236/jtr.2016.44019.