Pyrazinamide resistance in Mycobacterium tuberculosis isolates from northwest Iran and neighboring countries

Tuberculosis (TB) is a treatable disease that affects both humans and animals. Pyrazinamide (PZA), a first-line anti-TB drug with potent sterilizing activity, shortens treatment duration, yet its resistance patterns in northwest Iran remain underexplored. This descriptive cross-sectional study, conducted at the Tuberculosis and Lung Diseases Research Center in Tabriz, evaluated PZA resistance among ۱۰۰ Mycobacterium tuberculosis isolates from ۵۰ Iranian and ۵۰ foreign patients (from Nakhchivan Autonomous Republic and the Republic of Azerbaijan) referred for diagnosis and treatment between September ۲۰۱۴ and June ۲۰۱۹. Antimicrobial susceptibility testing (AST) was performed using the proportion method on Löwenstein-Jensen (LJ) medium for isoniazid (INH), rifampin (RIF), ethambutol (EMB), and streptomycin (STM), and Middlebrook ۷H۱۰ agar for PZA. Among ۱۰۰ isolates, ۶۰ (۶۰%) were resistant to at least one of the first-line drugs. Of these, ۱۸ (۳۰%) were resistant to PZA. Out of the PZA-resistant strains, only one isolate was resistant exclusively to PZA, and the rest were resistant to at least one of the main drugs (INH, RIF, STM, and EMB). Out of the ۶۰ strains, ۲۱ (۳۵%) were multidrug-resistant (MDR). Of these, ۱۲ (۵۷%) were resistant to PZA. Of the ۱۸ PZA-resistant strains, ۱۳ (۷۲.۲%) were isolated from foreign patients (P < ۰.۰۵). No PZA resistance was observed in isolates from East Azerbaijan province. These findings indicate a strong association between PZA resistance and MDR-TB, particularly in foreign patients, underscoring the need for routine PZA susceptibility testing, including pncA gene sequencing, and enhanced screening in border regions like Tabriz to control drug-resistant TB spread.

کلیدواژه ها:

Pyrazinamide ، Tuberculosis ، Drug resistance ، Northwest Iran