RESUMEN
INTRODUCTION: During 2001-2005, a regional anti-tuberculosis drug resistance survey was conducted in Castilla y León, Spain, in newly treated HIV negative tuberculosis (TB) patients. METHODS: A total of 918 Mycobacterium tuberculosis strains were studied (one strain per patient) from six hospitals corresponding to 46.7% of the total population of Castilla y León, using the proportion method on solid medium. RESULTS: Primary drug resistance was 4.2% (streptomycin 1.2%, isoniazid 3.2%, rifampin 0.3%, ethambutol 0.1% and pyrazinamide 0.5%). Mono-resistance was observed in 24 (2.6%) and resistance to both isoniazid and rifampin (multi-drug resistance) was detected in one case (0.1%). These results were not statistically significant compared to previous studies in the same Community. CONCLUSION: The incidence of primary drug resistance in the surveyed area was low, including isoniazid, allowing new anti-tuberculosis treatment with the standardised three-drug regimen to be started. Regular surveillance of drug resistance is recommended by the TB control programme in representative patient populations to optimize treatment regimens.