| In recent years, the transmission and prevalence of drug-resistant TB, especially Multi-drug resistant tuberculosis (MDR-TB) has become one of the biggest problems on controlling of TB. China was one of the higher TB burden countries in the world and was classified by the World Health Organization as one of the countries and regions which should be in the warning.As one of the most important cites in the western of China, Chengdu has a large population and mobility, so the prevalence rate and the drug resistance rate of TB is high. The incidence and spread of TB, which seriously affected the health of residents in the region, restricted the development of the local economic and social sustainable stable. Therefore, the most urgent thing is to strengthen monitoring and etiology research of tuberculosis, and to precede detection of drug resistance in patients with tuberculosis and molecular epidemiology in Chengdu. Thereby, the results may provide government and policy-making department the basis for making prevention and control strategies. It's of great significance in controlling the spread and prevalence of TB more effectively.ObjectiveThe study is to understand the levels and trend of first-line drug resistance of mycobacterium tuberculosis in Chengdu from 2007 to 2009, and to explore the change of drug resistance. Clinical isolates of mycobacterium tuberculosis in Chengdu is selected for analysis of genotype, and to explore the leading genotyping and characteristics of mycobacterium tuberculosis in Chengdu. Thereby, the results may provide government and policy-making department the basis for making prevention and control strategies.MethodsThe study was conducted in Chengdu TB Hospital, Chengdu Public Health medical treatment center. The 1235 clinical isolates were sampled from TB patients from 2007 to 2009. All 1235 cases is culture-positive and identified as MTB and absolute concentration method was used to test the resistance of first-line drug. Then isolates were selected randomly from Chengdu TB Hospital in 2010 and were typed by MIRU genotyping method. Data analysis were deal with by means of associated software toolResult1.The total rate of drug resistance was 28.83%. The initial and the acquired drug resistance rate were respectively 12.88% and 61.27%. The acquired drug resistance rate was higher than the initial drug resistance rate (χ2 = 312.7, P <0.05).2.The initial drug-resistance rate of SM, INH, RFP and EMB were respectively 7.86%, 7.50%, 7.26%, 5.56%. The acquired drug-resistance rate of RFP, INH, SM, EMB were respectively 55.15%, 37.50%,36.27%, 26.96%; The total drug-resistance rate of RFP, INH, SM, EMB were respectively 23.08%, 17.41%, 17.25%, 12.63 %.3.The initial multi-drug resistant rate (MDR, at least at the same time resistant to H, R) was 4.35%, and the acquired multidrug-resistant rate was 33.58%.The total rate of MDR was 14.01%. The acquired MDR was higher than the initial MDR (χ2 = 193.7, P <0.05).4.The initial drug-resistance rate from 2007 to 2009 were respectively 14.34%, 15.36%, 8.52% with gentle downward trend, and the acquired drug resistance rate were respectively 57.81%, 59.57%, 66.19% with increase trend year by year.5.The total drug-resistance rate from 2007 to 2009 were respectively 29.02%, 29.31%, 26.89% with gentle downward trend, and the rate of MDR were respectively 13.98%, 15.88%, 11.98%.6. Different strains showed different gene polymorphisms at different MIRU locus. The MIRU26 Locus has the highest diversity (h=0.653) and the next was MIRU31 locus and the MIRU40 locus. The MIRU02,MIRU24 has the lowest diversity.HGDI was 0.978.7. 51 Genotypes were obtained from the study result. In this study, 47 of all genotype were unique genotypes, and 18 were clustered genotype, and clustering rate was 27.7%(18/65) .The dominant strains of Mycobacterium tuberculosis genotype in Chengdu is"223325173533".Conclusion1.The status of TB drug resistance in Chengdu is still quite serious, and it's very important to further strengthen the monitoring and control of drug-resistant TB.2. The total drug resistance rate and the initial drug resistance with slow decrease indicate that the implementation of DOTS achieved some success in Chengdu, but the rate of acquired drug resistance with increased trend year by year indicate keeping good compliance and strengthen the management of drug resistance patients is the key to control TB. 3. It's the first time to study genotyping of Mycobacterium tuberculosis by MIRU typing technique in Chengdu. The study showed that the genotype of major epidemic strains in Chengdu is"223325173533", which should be of great significance in further studying in molecular epidemiology of tuberculosis in Chengdu. |
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