Abstract: Objective The aim of our study was to identify risk factors associated with drug resistant tuberculosis（TB） and Multidrug-resistant TB （MDR-TB） in new and retreatment cases.   Methods A national drug resistance TB baseline survey was carried out from April 2007 to December 2007, the survey with multistage cluster sampling, stratified by provinces, was conducted in 31 provinces, autonomous regions and municipalities directly under the central government. Seventy clusters representative of the tuberculosis prevention and control system of the country were randomly selected, eligible new diagnosed smear-positive tuberculosis patients including 51 new cases and 17 retreatment patients were recruited into each cluster during the survey. Relevant data of the patients were collected by physician through questionnaire. The patients were asked about the history of treatment through face-to-face interview; if possible, patients’ medical records were reviewed to validate the information. The accuracy of treatment history was confirmed by another physician through re-interviewing. Drug susceptibility testing to isoniazid, rifampicin, streptomycin, ethambutol, kanamycin and ofloxacin was performed on Lowenstein-Jensen (L-J)medium according to the proportion method.  Results The multivariate analysis results showed that new cases who had TB treatment for less than one month（OR=1.6, 95% CI＝1.1－2.1）were significantly more likely to have drug resistant TB; while female gender （OR=1.4, 95% CI＝1.0－2.1）and TB treatment （OR=2.4, 95% CI＝1.5－3.7）were independent risk factors for the presence of MDR-TB in new cases. Retreatment patients who were female gender（OR=1.7, 95% CI＝1.1－2.7）, who had previously been treated for TB for more than 2 times and the last treatment was provided by TB hospital （OR=4.0, 95% CI＝1.2－14.0）were significantly more likely to have drug resistant-TB. While female gender（OR=2.3, 95% CI＝1.5－3.6）, live in area with later DOTS implementation (after 2000)（OR=1.7, 95% CI＝1.2－2.4）, previous TB treatment for more than 2 times and the last treatment was provided by medical facility other than TB hospital（OR=3.3, 95% CI＝2.1－5.2）, previous TB treatment for more than 2 times and the last treatment was provided by TB hospital（OR=13.0, 95%CI＝3.9－46.0）were independent risk factors for the presence of MDR-TB in retreatment patients.   Conclusion New cases who have a history of TB drug treatment are at high risk for developing drug resistant TB and MDR-TB; while female gender and previous TB treatment for more than 2 times are independent risk factors for the development of drug resistant TB and MDR-TB in retreatment patients.

Key words: Tuberculosis, multidrug-resistant, Drug resistance, bacterial, Risk factors, Sex factors, Sampling studies