Evolution of In vitro Drug Susceptibility Testing of Pyrazinamide

Pyrazinamide is an important drug used in anti tubercular treatment which helps in killing old and semi dormant bacilli which are not metabolically active. Drug susceptibility tests are routinely performed before initiating multidrug drug resistant tuberculosis treatment. However, many Tuberculosis laboratories do not undertake drug susceptibility testing of Pyrazinamide as it is difficult to perform. In vitro drug susceptibility testing of Pyrazinamide requires acidic conditions which hinders the growth of TB bacilli. Hence, Nicotinamide a drug analog of Pyrazinamide was utilized for performing susceptibility testing. A literature review was undertaken and an inventory of in vitro tests for the drug susceptibility testing of Pyrazinamide was conducted. Media specifications and drug concentrations used for the susceptibility testing have also been described in chronological order. Solid culture method was used earlier, which gave consistent results but was time consuming. Liquid culture systems which had a shorter time of detection were also assessed and many studies were undertaken to evaluate their performance with respect to Pyrazinamide testing. The use of growth indicators and biochemical tests for Pyrazinamide testing has also been described.