Antibiogram - Mtb (pyrazinamide)

Pyrazinamide is an antibiotic used as part of combination therapy to treat active tuberculosis. It targets Mycobacterium tuberculosis, especially organisms in acidic, intracellular environments, and helps shorten the initial intensive phase of treatment. It is not used alone. Important concerns include liver toxicity and raised uric acid, so baseline and periodic liver function tests and monitoring for gout symptoms are recommended.

Pyrazinamide is used only in the initial two-month intensive phase of standard tuberculosis therapy because it is especially active against semi‑dormant bacilli in acidic lesions and speeds sterilization, allowing overall treatment shortening. Its greatest bactericidal effect occurs early; prolonged use raises risk of hepatotoxicity and hyperuricemia and can foster resistance if misused, so duration is limited to balance benefit and safety.

Pyrazinamide-resistant tuberculosis is managed by stopping pyrazinamide, continuing isoniazid, rifampicin and ethambutol, and adding a fluoroquinolone (moxifloxacin or levofloxacin) when indicated. Treatment duration is extended (commonly about 9 months) and individualized based on drug-susceptibility results, clinical response and specialist advice. Monitor closely for drug toxicity and adherence.

There is no specific antidote for pyrazinamide. Management is supportive: stop the drug, give symptomatic care (IV fluids, antiemetics), consider activated charcoal if ingestion was recent, and monitor liver function and serum uric acid. Treat complications (gout, hepatic injury). In severe overdose or renal failure, enhanced elimination such as hemodialysis may be considered; consult a toxicologist.

Pyrazinamide’s main risks are hepatotoxicity (can be severe), and hyperuricemia with gout flares. Other common effects include nausea, arthralgia and rash; rare serious hypersensitivity may occur. Risk of liver injury rises with age, alcohol use, pre‑existing liver disease, or concurrent hepatotoxic drugs. Baseline and periodic liver tests (and uric acid if symptomatic) are advised; stop therapy for significant transaminase elevations or clinical hepatitis.

Pyrazinamide is generally inexpensive because it’s an older, generic first-line tuberculosis drug and is commonly included in national TB programs and fixed-dose combinations. Many public health systems supply it free or at low cost. Out-of-pocket price can vary by country, brand, and formulation, but overall it is considered affordable compared with newer medications.