Abstract: Objective To investigate the drug resistant spectrum of patients with smear positive pulmonary tuberculosis (PTB) in Guangxi, and to clarify the distribution and law of drug resistance. Methods A prospective survey was conducted to recruit smear-positive PTB patients in the clinics of 30 TB control institutes in Guangxi. Sputum samples from 1765 cases were cultured and 1545 isolates of Mycobacterium tuberculosis were identified. Anti-TB drug susceptibility tests were conducted for 1545 isolates of Mycobacterium tuberculosis by conventional proportion method for isoniazide (H), rifampicin (R), ethambutol (E), streptomycin (S), ofloxacin (Ofx) and kanamycin (Km). Data for prior administration of anti-TB drugs were collected. Results The drug resistance rates of new cases to first line drugs was found in isoniazide 7.93% (94/1186), followed by streptomycin 6.24% (74/1186), rifampicin 3.20% (38/1186) and ethambutol 1.85% (22/1186), and those were 25.91% (93/359) for isoniazide, followed by rifampicin 25.07% (90/359), ethambutol 13.65% (49/359) and streptomycin 11.98%（43/359） in previously treated cases. The difference of proportion of any first line drug resistance between new cases and previously treated cases was statistically significant (χ²=43.174, P<0.01).There were 25 types of combinations of drug resistance among drug resistant cases. In the combinations to first line drugs, HRS (8 cases),HRE (5 cases) and HR (cases) were most common in new cases, and HRE (17 cases) and HR (15 cases) were most common in previously treated cases. Besides first line drug resistance, second line drug resistance was found in both new and previously treated patients. One cases was resistant to Km and 12 cases were resistant to Ofx in new cases. While in previously treated cases, the numbers were 6 and 31. Conclusion Results suggest that the orders of drug resistance rate of new and previously treated cases to first line drugs are different in Guangxi. There were 25 types of combinations of drug resistance among drug resistant cases, HRS and HR are most common in new cases, while HRE and HR are most common in previously treated cases.

Key words: Tuberculosis, pulmonary, Drug resistance, bacterial, Guangxi