| Tuberculosis is one of the most dangerous infectious diseases to human health in the world.It has characteristics of higher infection rate,drug resistance rate and death.As a new epidemiological research method,molecular epidemiology can provide effective information for the prevention and control of tuberculosis.Tracing the source of infection and verifying the way of transmission is a problem that has troubled the epidemiological research of tuberculosis for a long time.Genotyping is a powerful tool in molecular epidemiology and has irreplaceable advantages in the study of tuberculosis transmission.The ideal genotyping technique should be simple,rapid and the results can be compared between different laboratories.Xinjiang is located in the northwest border of China,bordering many countries with high infection of tuberculosis,the epidemic has special manner.In view of these situations,molecular epidemiological study of tuberculosis in Xinjiang region has important theoretical significance and urgent application needs.Therefore,McSpoligotyping and MIRU-VNTR,two suitable genotyping techniques,were used to study Mycobacterium tuberculosis samples in Xinjiang.The main results as follows:In chapter 1,we summarized the epidemic status,characteristics and causes of tuberculosis and the general situation of M.tuberculosis,introduced the general diagnostic methods of tuberculosis,and especially explained the drug resistance of M.tuberculosis.Then,the genotyping technology of M.tuberculosis and its role in the prevention and control of tuberculosis through molecular epidemiology were described in detail.According to the special geographical conditions and the state of the prevalence of tuberculosis in Xinjiang,the merit and demerit of molecular epidemiology for this disease were estimated.Finally,the purpose,content and significance of this thesis were presented.In chapter 2,McSpoligotyping system was used to classify M.tuberculosis samples in Xinjiang area.Using McSpoligotyping on 971 samples of M.tuberculosis from Xinjiang Uygur Autonomous Region Chest Hospital,and analyzing the genotypes of all strains,a total of 159 genotypes were found,among which 91 genotypes existed in SITVIT2 database,and the remaining 68 were new genotypes.After merging all the genotype families defined in SITVIT2 database and the results of the genotype family predicted by TB-Lineage,the family distribution of the 971 strains was obtained.According to the number of strains family from high to low were Beijing family(68.28%),T family(10.81%),CAS family(7.83%),Ural family(6.18%),MANU family(2.27%),LAM family(1.44%),H family(1.13%),X family(0.72%),EAI family(0.41%),S family(0.41%),BOV family(0.21%),Microti family(0.21%)and Undefined family(0.10%).The Beijing family is the main popular family.All 971 strains formed 47 clusters,with a clustering rate of 83.63%.The Hunst-Gastom distinguish index(HGDI)of McSpoligotyping was 0.5941.These results indicated that M.tuberculosis in Xinjiang area was dominated by Beijing family genotypes,with some unique genotypes in this area.For this reason,McSpoligotyping had lower resolution and higher clustering rate for M.tuberculosis in Xinjiang area,which was dominated by Beijing family strains.In chapter 3,the correlation between Beijing family strains and drug resistance was further analyzed by using the McSpoligotyping typing results of M.tuberculosis in Xinjiang and the previously collected drug sensitivity information of 5 first-line anti-Tb drugs and 12 second-line anti-Tb drugs.The results showed that there was no significant difference between the resistance rate of Beijing family strains and non-Beijing family strains in Xinjiang area(P value is larger than 0.05).Compared with 5 relatively large number families of Beijing family,T family,CAS family,Ural family and MANU family,there is no significant difference(P value is larger than 0.05)in the overall drug resistance rate of the five first-line drugs in the five families,but there is significant difference(P value is less than 0.05)in the multiple drug resistance(MDR).Further analysis and comparison among families reveals that,drug resistance rate to isoniazid of Beijing family strains,T family strains and CAS family strains are significantly higher than Ural family strains;drug resistance rate to streptomycin of Beijing family strains and T family strains are significantly higher than Ural family strains.For MDR rate,CAS family strains are significantly higher than T family strains and Ural family strains.Through the comparison of different years,there was no significant difference in the drug resistance rate and MDR ratio of various first-line drugs between Beijing family and non-Beijing family strains in different years.In chapter 4,MIRU-VNTR genotyping technique was used to classify M.tuberculosis in Xinjiang area.First of all,we consule literature to select appropriate MIRU-VNTR typing sites,and a VNTR 9+3 typing system was determined to conduct typing experiments on 257 M.tuberculosis samples that met the requirements of sample concentration.The results showed that 257 specimens were divided into 190 genotypes by VNTR-9,among which 105 strains were divided into 37 gene clusters,with a clustering rate of 26.46%and the remaining 152strains showed s unique VNTR-9 genotype,suggesting higher genotype diversity.Further HV-3 typing was performed for 105 cluster strains,39 strains were divided into 19 gene clusters,and the remaining 66 strains showed a unique VNTR-9 genotype.In total,257 samples were divided into 238 genotypes by VNTR 9+3,among which 38 strains of M.tuberculosis were divided into 19 gene clusters,with a clustering rate of 7.39%.For the 257 samples,the HGDI of VNTR 9+3 typing was 0.9994 and McSpoligotyping was 0.6053.Further studies on the Beijing family strains of these samples,we found that the HGDI of McSpoligotyping was only 0.1136,VNTR-9 was 0.9892,and VNTR 9+3 was 0.9989.Allele polymorphism analysis of 9 VNTR loci showed that allele polymorphism of each VNTR locus was different.The highest VNTR polymorphism was Qub18(h=0.7814)and the lowest was MIRU40(h=0.3485).Among the 9 loci,QUB18,QUB-11b,MIRU26,QUB-26,Mtub21 and VNTR2372 had higher resolution(h>0.6),indicating that VNTR locus of M.tuberculosis in Xinjiang area had a relatively higher allele polymorphism.By cluster analysis,VNTR 9+3 divided all strains into 3 groups,group ? included all Beijing family strains,non-Beijing family strains formed group ? and group ?.There was no significant differences between these 3 groups.In conclusion,this research provides effective information to understand the genetic diversity and transmission dynamic of M.tuberculosis in Xinjiang area.This research indicates that Xinjiang area has a M.tuberculosis flora structure which is high diversity dominated by Beijing family strains,drug resistance may exist between diffirent groups of strains.Besides,higher drug-resistance rate and lower cluster rate indicate that the happens of M.tuberculosis drug-resistance are not relative to recent transmission,on the contrary,are relative to recurrence and inappropriate treatment.So we need more effective control strategy,for example,strengthening compliance of patients to treatment and standardized medication,to prevent the occurrence of drug-resistance tuberculosis?... |
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