| TB, as one of the major infectious diseases in China, is a serious harmful infectious disease to humans primarily infected with M.TB. The WHO declared TB a global epidemic since1993because of it’s recurrence in the nineteen eighties. Due to the emergence of drug-resistant TB, and TB control measures to abate and AIDS (HIV/AIDS) epidemic, The WHO estimated that8million people suffered from and2million died of TB every year. DOTC has been implemented since1991and the full implementation of a modern TB control strategy from the beginning of2001.8.29million cases with pulmonary tuberculosis including4.5million cases of smear-positive pulmonary TB have been discovered and treated in the last10years, avoiding about40million healthy people from being infected with M.TB. The Smear-positive TB rate was66/10million in2010down61%from2000.However, prevention and control work of TB in china is facing many new problems and challenges. China remains to be one of the countries with a high TB burden. At present the annual TB patients’ number is approximately1.3million ranked second in the world and accounts for14%of the global incidence according to WHO assessments. TB incidence was at about1million and was previously always at the forefront of infectious diseases. The MDR-TB hazard of which new cases are approximately120thousand, is becoming increasingly prominent. MDR-TB may be the star of the TB epidemic in the next few years. The number of TB/HIV co-infected patients will increase, which will cause the need for preventive work to be strengthened. The western regions and rural areas outlook for TB prevention and control situations are grim. The TB control service system and prevention ability in China also can’t handle the new situation and prevention and control work because of a lag in infrastructure construction, weak primary prevention, has difficultly in the management of floating patients treated for TB, and a lack of public awareness of TB prevention and control task are compounding the problem. The rural areas are specifically still very troublesome, needing long-term and unremitting efforts to try to remedy this dilemma.The study was conducted in Xianju agricultural County in Taizhou, in which DOTC has been implemented for several years. The subjects were all culture-positive pulmonary TB patients newly diagnosed or retreated during the12months of2011to2012. Through the collection of basic information and sputum specimens of patients’, M.TB were stained and cultured. All M.TB strains were tested for drug sensitivity (INH and RFP) and genotyped using the15loci of MIRU-VNTR, at the same time using the multiplex PCR method for the detection of RD105missing fragments to distinguish Beijing genotypes and non Beijing genotypes, so as to explore epidemiology, drug sensitivity and gene polymorphism of M.TB in the rural areas of Taizhou. Through mastering the basic characteristics and possible transmission of TB, scientific measures of TB prevention and control can be provided.[Results]1. Epidemic characteristics of TBThis study included89TB patients, in which men accounted for75.3%(67) and women24.7%(22).The average age of TB patients were51.4±18.2years old. The oldest ones were88years old, the youngest ones15years old, for a median of52years. The largest group having44patients was30-60ages, accounting for49.4%,while the second group accounting for34.8%(3leases) was≥60ages. Most of the patients were farmers, accounting for80.9%, while non-farmers and students accounted for15.7%and3.4%.78of them were newly diagnosed patients that accounted for87.6%and previously treated patients were11cases, accounting for12.4%. Local cases were79, accounting for88.8%, and field cases were10, accounting for11.2%. Sputum smear positive were47cases, accounting for51.7%, and negative were42cases, accounting for48.3%.2. Culture and Drug susceptibility of M.TB.80strains of M.TB were isolated, also8strains of M.avium-intracellulare and1stains of M kansasii isolated.The drug resistant rate to INH or RFP of80M.TBs strains was8.8%(7/80), all strains were isolated from newly diagnosed patients. The drug resistant rate to INH and RFP was7.5%(6/80), in which three strains were isolated from previously treated patients. There were4cases of M.avium-intracellulare and7cases of M.TB including3cases of MDR-TB in11previously treated patients.3. Drug susceptibility of different treatment patientsIn all74newly diagnosed patients,64cases, accounting for92.5%, were drug susceptivity accounted for86.5%(95%CI76.5%～93.3%)and10cases were drug resistance accounted for13.5%(95%CI6.7%～23.5%). In all6previously treated patients,3cases were drug susceptive accounting for50.0%(95%CI11.8%～88.2%) and other3cases were drug resistant. The statistical analysis showed that there was no difference between the newly diagnosed and previously treated patients in general drug resistance(χ2=0.04, P=0.079>0.05), also between the newly diagnosed and previously treated patients in resistance type (χ2=4.55, P=0.102>0.05).4. Drug susceptiveness of different genotypeIn all39Beijing genotype strains,33strains were drug susceptive, accounting for84.6%(95%CI69.5%-94.1%)and6cases were drug resistant accounting for15.4%(95%CI5.9%-30.1%). In all41non-Beijing genotype strains,34cases were drug susceptive, accounting for82.9%(95%CI67.9%-92.8%) and the other7cases were drug resistant, accounting for17.1%(95%CI7.2%-32.1%). The statistical analysis showed that there was no difference between the Beijing and non-Beijing genotype in drug resistance(χ2=0.04, P=0.839>0.05), also between the Beijing and non-Beijing genotype in in resistance type (χ2=1.93, P=0.380>0.05)5. Analysis Influencing factors of drug resistant TB.Single factor analysis of logistics found the MDR-TB population was associated with retreatment (P<0.05), and age, sex, occupation, household register, treatment, sputum smear, genotype had no obvious correlation with drug-resistant patient population distribution. Multiple logistic analyses found MDR-TB was associated with retreatment. Retreatment TB patients were predominant in the population occurrence of multiple drug resistant TB (retreatment/initial treatment: OR:15.854;95%CI:1.866-134.677).6. Genotyping of M.TB15MIRU-VNTR loci were used for genotyping all M.TB strains. Every locus showed different polymorphism. The highly HGI locus was MIRU26(HGI=0.865) and the lowest HGI locus was ETRC(HGI=0.165). There were10loci in which HGI was higher than0.5.The15loci of MIRU-VNTR genotyping showed that80strains of M.TB could be categorized into78genotypes, including76unique genotypes and two clusters each contained two strains. The clustering rate was2.5%. According to the Bionumerics analysis,78genotypes could be divided into eight groups(Ⅰ, Ⅱ,Ⅲ、 Ⅳ、Ⅴ、Ⅵ、Ⅶ、Ⅷ).8.75%were group I including7genotypes,11.25%were group II including8genotypes,55.0%were group III including43genotypes,6.25%were group Ⅳ including5genotypes,2.5%were group V including2genotypes, 8.75%were group VI including7genotypes,5.0%were group Ⅶ including4genotypes,2.5%were group Ⅶ including2genotypes.The study showed that there was a low level prevalence of tuberculosis and a drug resistance rate below the national level in the rural area of Taizhou. The statistical analysis showed that there was no difference between the newly diagnosed and previously treated patients in general drug resistance, also between the Beijing and non-Beijing genotypes in general drug resistance. Non-Beijing genotypes were the dominant strains. The15loci of MIRU-VNTR genotyping verified that relapses and re-infections not of recent transmission were the dominant epidemic character of tuberculosis in the rural area of Taizhou, because of the low clustering rate. |
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