First-line anti-tuberculosis drug resistance patterns and trends at the national TB referral center in Iran--eight years of surveillance.

OBJECTIVE: Resistance to anti-tuberculosis (anti-TB) drugs is becoming a major and alarming threat in most regions worldwide.

METHODS: This was a descriptive cross-sectional study at a tertiary hospital in Iran, using patient medical records for 2000-2003. The findings were analyzed following the same framework as that used for previous reports from this center.

RESULTS: Among 1556 TB patients, drug susceptibility testing (DST) was performed for 548 culture-positive cases. Anti-TB drug resistance to both isoniazid and rifampin was identified in 10 (2.8%) of the new TB cases (multidrug-resistant TB; MDR-TB). Any resistance was detected in 228 (41.6%), showing an increasing trend in both new and retreatment cases. The data analysis revealed that drug-resistant TB had a statistically significant association with Afghan ethnicity, age>65 years, and the type of disease (retreatment vs. new TB case) (p<0.05). Also, assessment of the drug resistance trends showed a significant increase in resistance to any anti-TB agent, to isoniazid, and to streptomycin in new cases, and to all of the first-line anti-TB drugs in retreatment patients.

CONCLUSIONS: There has been an increasing trend in drug resistance in recent years, particularly in retreatment cases. Hence, revision of the national TB control program, reevaluation of the role of the World Health Organization category II (CAT II) regimen, as well as the conducting of a nationwide drug resistance survey, are recommended.