Representative drug susceptibility patterns for guiding design of re-treatment regimens for multidrug-resistant tuberculosis in Iran.

Background and objective: The prevalence of multidrug-resistant tuberculosis (MDR-TB) has increased substantially in the past 20 years, however, there are no data specific to Iran. This study investigated patients suspected to have MDR-TB, attending the TB referral hospital in Iran. Methods: All patients suspected of having MDR-TB on hospital admission in the period 2003-2005 were included in this study. Sputum from all patients was tested for smear and culture, and drug sensitivity testing was performed using the proportion method. Patients were categorized into three groups based on their history of medical treatment. Group I consisted of patients with CAT I regimen failure; Group II consisted of patients with a history of CAT II regimen failure and Group III comprised patients with a history of more than two courses of irregular CAT I anti-TB regimen. Results: There were 105 patients recruited; 32 in Group I, 53 in Group II and 20 in Group III. There were no significant differences between the three groups in their resistance to first-line anti-TB drugs. Fifty-five patients were diagnosed with MDR-TB. The prevalence of MDR-TB was 56% (18 cases) in group I, 49% (26 cases) in group II and 55% (11 cases) in group III. No significant difference in the pattern of drug resistance was observed between the three groups. Conclusion: The prevalence of MDR-TB was high in this study. The lack of response of MDR-TB patients to CAT II treatment indicates that antibiotic sensitivity testing is essential in patients with CAT I treatment failure.