Analysis of the drug resistance patterns and resistance rates among smear positive TB patients in Wuhan city

Objective To analyze the resistance characteristics of different registration classification smear positive TB patients(especially MDR-TB) and to understand the risk factors in order to provide reliable references for development of drug-resistant TB control strategy.Methods Two sputum samples were collected from each smear positive patient in 3 categories-new,re-treatment(relapse,transfer in and others) and treatment failure(failure of new patient,retreatment patient and new patients who remain smear positive after 3 months of treatment) for sputum culture by proportional method,six kinds of anti-TB drugs(INH,RFP,EMB,S,Km,Ofx) were tested for susceptibility.Between December 2006 and March 2012,a total of 2110 cases of smear positive TB patients were sputum cultured,in which 1947 cases(92.3%) were culture positive;through drug susceptibility test(DST) and bacterial typing,1800 cases of Mtb(92.4%) were identified eventually.Results Among the 1800 Mtb cases,a total of 794 cases(44.1%,794/1800) were identified as drug-resistant TB,out of which,244 cases(13.6%,244/1800) were single-drug-resistant(SDR) TB,155 cases(8.6%,155/1800) were poly-drug-resistant(PDR) TB,395 cases(21.9%,395/1800) were MDR-TB,the detection rate of MDR-TB is significantly higher than SDR-TB and PDR-TB(χ2=43.4,χ2=123.6,P0.01).The detection rate of SDR for new,re-treatment and treatment failure TB patients was 11.9%(57/480),14.4%(159/1107)and 13.1%(28/213)respectively,the diffe-rence is not statistically significant(χ2=0.33,P=0.85);the detection rate of PDR for new,re-treatment and treatment failure TB patients was 5.4%(26/480),9.8%(109/1107) and 9.4%(20/213) respectively,the difference is not statistically significant between retreatment and treatment failure cases(χ2=0.04,P=0.84).however,they are higher than that of new TB cases(χ2=8.53,P=0.01);the detection rate of MDR for new,re-treatment and treatment failure TB patients was 14.4%(69/480),22.5%(249/1107) and 36.2%(77/213)respectively,the detection rate of treatment failure TB patients is higher than that of new and re-treatment TB patients(χ2=17.92,χ2=42.07,P0.01).Conclusion The detection rate of drug resistant TB is high among smear positive TB patients in Wuhan.The diversity and complexity of drug resistant spectrum poses a threat to TB control in China.