Pyrazinamide is one of the four first-line agents used to treat Mycobacterium tuberculosisinfections. It is a unique agent in regards to susceptibility testing because it requires testing under acidic conditions, and it is well documented in relevant literature that current broth methods tend to overcall resistance to this agent. In these cases, the broth susceptibility test indicates that the organism is resistant to pyrazinamide. Since there are only four first-line agents for treating Mycobacterium tuberculosis infections, incorrectly excluding one of them could reduce the likelihood of successful treatment.
Relevant literature has found that the majority of cases associated with pyrazinamide resistance are due to mutations in the pncA gene. These findings led Mayo Clinic to validate a method for sequencing the pncA gene as an additional tool to confirm broth susceptibility testing results.
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