Objective To analyze the drug resistance situation of patients with suspected multidrug-resistant pulmonary tuberculosis (MDR-PTB) in TB control institutes and TB designated hospitals in Beijing,to provide suggestions for clinical diagnosis,treatment,and control.Methods We made a retrospective analysis,including preliminary bacteria identification and drug susceptibility testing of the bacteria isolated from the positive sputum specimens of the 881 suspected MDR-PTB patients from 14 TB control institutes and 6 TB designated hospitals in Beijing between January 2014 and December 2016.We collected their drug susceptibility testing results against INH,RFP,Sm,EMB,Lfx,Am,Cm,Pto,and PAS.SPSS 17.0 was used for statistical analysis.We analyzed and summarized the drug resistance situation of suspected MDR-PTB patients in those 3 years.Results In the 881 suspected MDR-PTB patients,the isolation rate of Mycobacterium tuberculosis complex group was 88.6％ (781/881).The isolation rate of non-tuberculous mycobacterium (NTM) was 11.4 ％ (100/881).The total drug resistant rate of the clinical isolates of Mycobacterium tuberculosis complex group was 33.3 ％ (260/781).The multidrug-resistance (MDR) rate was 17.2％ (134/781).The proportion of high-level of resistance rates (defined as ＞67.0％) against the four first-line TB drugs (INH,RFP,Sm and EMB) was 69.0％ (127/184),57.1％ (92/161),60.5％ (107/177) and 31.7％(19/60) respectively.Conclusion It is very necessary to carry out a drug sensitive test for the suspected MDR PTB patients in Beijing,and the epidemic situation of TB resistance faced in Beijing is still very severe.

病案故事 1 2016年3月,17岁的高三学生小王,因考前体检发现右上肺斑片状阴影,并有空洞(临床无任何症状),诊断为活动性肺结核,予2个月异烟肼、利福平、乙胺丁醇、吡嗪酰胺强化治疗,4个月异烟肼、利福平、乙胺丁醇巩固治疗,休学在家口服药物治疗,并由家庭成员监督其完成抗结核治疗,定期复查.治疗6个月后病灶吸收,完成疗程,继续上学.

Objective To analyze the test results of tuberculosis prevention and control for the undergraduate of the Capital medical university,discusses how to improve teaching methods.Methods After teachers taught contents of the basic theoretical knowledge with traditional teaching method.Students were sorted by their ID and divided into 7 groups for the different topic,there were 4 groups each of 5 students,3 groups each of 6 students.Students were arranged to collect materials about different topic and give a special report.The report contents of fifth group and the seventh group were not directly involved the contents of teaching,those students needed to col lect relevant materials.Then students took part in an open-book exam.Through one-factor ANOVA and wilcoxon rank sum test,compared differences of examination results of different subjects or different report group,explored the better teaching model for learning.Results The average score of examination is 69.6 ± 6.6,52.6％ of students scores between 61-70 fraction;The fifth exam topic was monitoring analysis and evaluation index of tuberculosis and its significance,its average score was 17.5±2.0 points (20 points per exam topic,a total of 5),that was the highest among five exam topic,it was significantly higher than the average scores first topics (13.5 ± 2.9),second topics (11.3 ± 2.8),third topics (13.5 ± 2.5),fourth topics (13.9 ± 1.8) (F =32.14,P＜ 0.01).The report title and content of seventh group was not directly involved in teachers' collective teaching content.So students of seventh group needed to collect the data and material,to learn and think autonomously.Average score (14.6±3.0) of seventh group has a trend that was higher than other groups (13.0±2.6,13.9±2.6,13.5±3.4,14.4±2.6,14.1±3.7,13.8±3.7),but there had not statistical significance (H=7.42,P＞0.05).The report con tent was related highly with first exam,the average rank (28.8) of first exam topic of seventh group was obviously higher than other groups (15.1,21.2,26.3,22.0,12.0,12.1) (H=12.77,P＜0.05).Conclusion In teaching activities of TB prevention and control,exam scores of active learning group was better than that of non-Active Learn ing Group.It was suggested for teaching of TB prevention and control,firstly carry out case-based teaching several times,improve students' active learning motivation,so that strengthen the basic theoretical knowledge.Finally,organize a problem-based learning (PBL) teaching to extend teaching ideas.

Objective To analyze the distribution and drug resistance of nontuberculous mycobacteria( NTM) in Beijing.Methods Using PCR-fluorescence probe method we identified 1552 mycobacterial isolates in 2009 and 1553 mycobacterial isolates in 2013, which were stored by Beijing Research Institute for Tuberculosis Control.All identified NTM strains were confirmed by 16S rRNA gene sequencing , and drug sensitivity testing was performed by using 1% ratio method.SPSS 13.0 was used for statistical analysis.Results The isolation rate for NTM in 2009 and 2013 was 3.8%(59/1552),and 4.6%(71/1553) respectively.A total of 130 NTM strains were identified to 13 species by 16S rRNA gene sequencing , including M.intracellulare strains 39.2%( 51/130 ) , M.kansasii strains 37.7%( 49/130 ) , M.avium strains 6.9%(9/130), M.abscessus strains 5.4%(7/130), M.fortuitum strains 3.0%(4/130), M.gordonae strains 1.5%( 2/130 ), M.xenopi strains 1.5%( 2/130 ), M.scrofulaceum, M.Phlei, M.smegmatis, M.vaccae, M.neoaurum, M.kumamotonense 1 strain each.For the patients infected with NTM, 87 were male and 43 were female, with an average age of 55 years.The results of drug sensitivity test from 97 strains of NTM showed that isoniazid and p-aminosalicylic acid showed the highest drug resistant rate of 98%( 95/97 ) , followed by streptomycin 94.8%( 92/97 ) , capreomycin 81.4%( 79/97 ) , amikacin 69.1%( 67/97 ) , levofloxacin 56.7%( 55/97 ) , rifampicin 54.6%( 53/97 ) , prothionamide 51.5%(50/97), and ethambutol 50.5%(49/97).Conclusions Mycobacterium intracellulare and Mycobacterium kansasii were the main strains isolated from patients infected with NTM in Beijing .Patients infected withNTM were mostly males.NTM showed high resistance to anti-tuberculosis drugs.

目的 探讨北京地区结核分枝杆菌卷曲霉素(Cm)和阿米卡星(Am)耐药与rrs基因和tlyA基因突变相关性.方法 采用比例法对保存的临床菌株进行Cm和Am药敏试验测定,并对其中的临床菌株rrs基因和tlyA基因进行PCR、测序分析.筛选得到了10株Am耐药菌株、25株Cm耐药菌株、15株Am和Cm交叉耐药菌株,并选择了30株敏感菌株作为对照分析.数据采用SPSS 17.0进行统计分析,组间率的比较采用Fisher精确概率法检验,P＜0.05为差异有统计学意义.结果 tlyA基因突变结果显示,Cm耐药菌株有6株突变(24.0％,6/25),与敏感菌株相比差异有统计学意义(P＜0.05),Am耐药菌株、Am和Cm交叉耐药菌株与敏感菌株相比差异无统计学意义(P＞0.05);在m基因检测中,Am耐药、Cm耐药、Am和Cm交叉耐药突变率分别有30.0％(3/10)、8.0％(2/25)和26.7％(4/15),敏感菌株中也有10.0％(3/30)突变株,3组耐药菌株与敏感菌株比较,差异均无统计学意义(F=2.353、0.06、1.161,P值均＞0.05).在3组中,rrs基因A1401G突变位点突变比例分别是10.0％(1/10)、8.0％(2/25)和13.3％(2/15),1株在Am和Cm交叉耐药双位点突变,共计6株A1401G位点突变菌株,与敏感菌株比较无统计学意义(P＞0.05).另一突变位点C1402T在Am、Am和Cm交叉耐药中各1株.结论 结核分枝杆菌tlyA基因可能与Cm耐药相关,与Am耐药不相关;rrs基因A1401G和C1402T突变可能与Am和Cm交叉耐药有关.

目的 比较传统培养法和PCR-荧光探针法在分枝杆菌的鉴定中有无差异.方法 对1552株分枝杆菌临床分离株同时用传统培养法对硝基苯甲酸(PNB)、噻吩二羧酸肼(TCH)培养基生长试验及PCR-荧光探针法进行鉴定,结果有差别的菌株用16SrRNA基因测序的方法进行确认.结果 两种方法非结核分枝杆菌的符合率为75.4％(46/61),结核分枝杆菌复合群的符合率为99.0％(1491/1506),总体符合率为99.0％(1537/1552).两种方法检测结果不同的15株样本经16SrRNA基因测序进行鉴定,PCR-探针法与16SrRNA结果一致的有14株,另外1株经传代分离纯化后测序结果为结核分枝杆菌和戈登分枝杆菌的混合菌.非结核分枝杆菌对PNB培养基的敏感度为21.7％(13/60),有0.1％(1/1492)的结核分枝杆菌复合群对PNB表现耐受性.对PNB敏感的13株非结核分枝杆菌中,有76.9％(10/13)为堪萨斯分枝杆菌.结论 部分非结核分枝杆菌使用PNB-TCH生长试验进行鉴定时会出现误判,而PCR-荧光探针法鉴定结核分枝杆菌复合群和非结核分枝杆菌的准确性较高.

结核分枝杆菌基因分型是监测结核病流行和传播的有效手段.用于结核病流行病学研究的分型方法已有很多种,但不同的基因分型方法各有特点,应根据不同的研究目的选择合适的方法,或者多种方法结合使用,并结合传统的流行病学资料综合分析可得出可靠结论.结核分枝杆菌分型鉴定技术在研究结核分枝杆菌菌种鉴定、耐药和耐多药检测,以及结核病的病原演变、跟踪和确定传染源、确定流行病学事件、揭示疾病传播机制等方面发挥着重要的作用.同时,此类研究正与新兴的遗传信息学相结合,相应成果能够为更科学地制定结核病防控策略提供依据.

目的 对荧光显微镜检测抗酸杆菌的应用进行评价.方法 5个结核病专业诊疗机构共收集2157份标本,每份标本均采用荧光染色(FS)、萋-尼染色(Z-N染色)镜检.其中1245份标本同时进行传统培养检查,并且以培养结果为最终的金标准,计算FS和Z-N染色镜检方法的敏感度、特异度和正确指数[正确指数=(敏感度+特异度)-1=1-(假阴性率+假阳性率)].所有结果采用SPSS 17.0统计软件完成配对x2检验,以P＜0.05为差异有统计学意义.结果 全部标本荧光染色镜检阳性率为10.8％(234/2157),萋-尼染色镜检阳性率为8.8％(190/2157),两种镜检方法阳性率差异有统计学意义(x2=25.473,P＜0.001).初诊标本经荧光染色镜检的阳性率为15.9％(179/1127),萋尼染色阳性率为13.2％(149/1127),荧光染色镜检检出抗酸杆菌的能力较萋-尼染色高20.1％;两种镜检方法检查初诊标本的阳性率,差异有统计学意义(x2=18.000,P＜0.001).同时完成涂片和培养的标本,荧光染色镜检阳性率13.8％(172/1245),培养阳性率15.2％(189/1245),两者比较差异无统计学意义(x2=2.173,P=0.140).同时完成涂片和培养的初诊标本,荧光染色镜检阳性率16.4％％(128/781),培养阳性率19.7％(154/781),分离培养阳性率较荧光染色阳性率高20.3％,差异有统计学意义(x2=7.861,P＜0.01).荧光染色镜检的敏感度为60.3％(114/189)、特异度为94.5％(998/1056),假阴性率为39.7％(75/189)、结果正确指数为0.548,萋-尼染色镜检相应指标分别是56.6％(107/189),97.1％(1025/1056),43.4％(82/189)和0.537.结论 与萋-尼染色镜检比较,荧光染色镜检具有更高的敏感度和很好的特异度;能够提高工作效率,降低工作强度,适合在工作量较大、人力资源紧张的基层实验室开展.

Background: Tuberculosis (TB) is a serious problem in China. While there have been some studies on the nationwide genotyping of Mycobacterium tuberculosis (M. tuberculosis), there has been little detailed research in Beijing, the capital of China, which has a huge population. Here, M. tuberculosis clinical strains collected in Beijing during 2009 were genotyped by classical methods.Methodology/Principal Findings: Our aim was to analyze the genetic diversity of M. tuberculosis strains within the Beijing metropolitan area. We characterized these strains using two standard methods, spoligotyping (n = 1585) and variable number of tandem repeat (VNTR) typing (n = 1053). We found that the most prominent genotype was Beijing family genotype. Other genotypes included the MANU, T and H families etc. Spoligotyping resulted in 137 type patterns, included 101 unclustered strains and 1484 strains clustered into 36 clusters. In VNTR typing analysis, we selected 12-locus (QUB-11b, MIRU10, Mtub21, MIRU 23, MIRU39, MIRU16, MIRU40, MIRU31, Mtub24, Mtub04, MIRU20, and QUB-4156c) and named it 12-locus (BJ) VNTR. VNTR resulted in 869 type patterns, included 796 unclustered strains and 257 strains clustered into 73 clusters. It has almost equal discriminatory power to the 24-locus VNTR.Conclusions/Significance: Our study provides a detailed characterization of the genotypic diversity of M. tuberculosis in Beijing. Combining spoligotyping and VNTR typing to study the genotyping of M. tuberculosis gave superior results than when these techniques were used separately. Our results indicated that Beijing family strains were still the most prevalent M. tuberculosis in Beijing. Moreover, VNTR typing analyzing of M. tuberculosis strains in Beijing was successfully accomplished using 12-locus (BJ) VNTR. This method used for strains genotyping from the Beijing metropolitan area was comparable. This study will not only provide TB researchers with valuable information for related studies, but also provides guidance for the prevention and control of TB in Beijing.

Objective To evaluate the effectiveness of manual mycobacteria growth indicator tube( M-MGIT)system for rapid detection of Mycobacterium tuberculosis. Methods Five hundred and twenty-six sputa of newly diagnosed tuberculosis patients were collected from January 2012 to February 2013 in the tuberculosis clinic of Chaoyang District Center for Disease Control and Prevention. All the sputa were cultured by Lwenstein-Jensen( L-J) medium,M-MGIT system and automated BACTEC MGIT 960( A-MGIT) system. The χ2test and t test were used to analyze statistically the result,and if P < 0. 05,the results had the significant difference. Results Of the 526 sputa specimens,261( 49. 6%) were isolated as Mycobacterium tuberculosis strains. The positive culture rates of the M-MGIT,A-MGIT and L-J method were 48. 7%( 256/526),49. 0%( 258/526) and 41. 3%( 217/526) respectively. The culture positive rates of M-MGIT and A-MGIT both were significantly higher than that of L-J method( χ2M-MGIT and L-J= 5. 84,χ2A-MGIT and L-J= 6. 45,both P < 0. 05),but the difference between M-MGIT and A-MGIT was not significant( χ2M-MGIT and A-MGIT= 0. 02,P > 0. 05). The mean times of detection with M-MGIT system,A-MGIT system and L-J method were 13( 13 ± 6) days,12( 12 ± 6) days and 24( 24 ± 9)days,respectively. Comparing the mean detection times of M-MGIT with L-J method and A-MGIT with L-J method,both differences were statistically significant( t M-MGIT and L-J= 15. 84,t A-MGIT and L-J= 18. 32,P < 0. 05). Comparing the mean detection time of M-MGIT system with A-MGIT system,the difference had not statistical significance( t = 1. 89,P > 0. 05). The rates of contamination were 4. 6%( 24/526) with the M-MGIT system,4. 9%( 26/526) with A-MGIT system and 4. 1%( 43/1052) with L-J medium,the difference was not statistically significant( χ2= 0. 64,P > 0. 05). Conclusion MMGIT system is a rapid detection method of Mycobacterium tuberculosis with a higher positive detection rate,do not need expensive equipment,is suitable for the routine diagnosis in the primary tuberculosis laboratories.

Objective To explore the status and effect of standard treatment regimens of retreatment pulmonary tuberculosis patients in Beijing.Methods This was a retrospective study.The bacteriologically confirmed retreated pulmonary tuberculosis cases registered from 2009 to 2010 in Beijing were enrolled and divided into rifampin-sensitive(138 cases) and rifampin-resistant(39 cases)groups,according to the results of drug susceptibility test.The cases in each group were divided into isoniazid-sensitive and isoniazid-resistant groups.There were 114 cases sensitive to both isoniazid and rifampin,24 resistant to isoniazid and sensitive to rifampin,12 sensitive to isoniazid and resistant to rifampin,and 27 resistant to both isoniazid and rifampin.Standard treatment regimens(2HRZES/6HRE)were applied,and the effect was retrospectively analyzed.Results In isoniazid-sensitive and resistant groups,the sputum conversion rates were 92.9%(117/126)and 66.7%(34/51),and the treatment success rates were 87.3%(110/126)and 60.8%(31/51)respectively.There was no statistical significant difference in the sputum conversion and the treatment success between two groups(χ2 MH value were 2.183 and 1.974,both PMH value >0.05).In rifampin-sensitive and resistant groups,the sputum conversion rates were 94.2%(130/138) and 53.8%(21/39),and the treatment success rates were 88.4%(122/138) and 48.7%(19/39) respectively.The differences in the sputum conversion and the treatment success between two groups were statistical significant(χ2 MH values were 16.199 and 12.686,both PMH value <0.001).Conclusion The effect of standard regimens of rifampin-sensitive pulmonary tuberculosis has been approved,while the rationality of applying standard regimens to those rifampin-resistant cases needs to be discussed.

Objective To understand the drug resistance of retreatment tuberculosis patients in Beijing,and to provide evidence for Beijing TB control.Methods One hundred and ninty-five retreatment tuberculosis patients registered in TB control organizations from 2009 to 2010 that had performed both the 1st-line and 2nd-line drug susceptibility tests were collected and analyzed.Chi-square test was used for comparing difference of drug resistant rate,α=0.05.Results The resistance rate of 1st-line anti-TB drugs was 56.4%(110/195),for 2nd-line anti-TB drug resistance rate was 63.6%(124/195),multi-drug resistant(MDR) rate was 28.2%(55/195),extensively-drug resistant(XDR) rate was 3.1%(6/195).Drug resistance rate in the top 5 of the 9 drugs tested were Pto 57.9%(113/195),INH 42.6%(83/195),EMB 36.4%(71/195),S 34.9%(68/195) and RFP 33.8%(66/195).There were no significant difference of drug resistance in different gender[male 78.8%(119/151),female 79.5%(35/44),χ2=0.011,P>0.05],age group["15～years old" 82.9%(34/41),"30～years old" 83.8%(57/68),"45～years old" 79.2%(38/48),"60～years old" 65.8%(25/38),χ2=5.328,P>0.05],region[local census register,79.2%(103/130),Nonlocal census register 78.5%(51/65),χ2=0.015,P>0.05]and patient classification [relapse 77.7%(122/157),initial treatment failure 84.6%(11/13),other retreatment 84.0%(21/25),χ2=0.824,P>0.05].Conclusion The drug resistance of retreatment tuberculosis is serious in Beijing.We should strengthen the research on existing treatment methods in TB control in order to meet the evolving needs of capital tuberculosis control under the new situation.

Objective To study para-aminosalicylic acid(PAS) resistance rates in M.tuberculosis isolates and the relationship with thyA gene mutation.Methods Ninety-six M.tuberculosis strains were isolated and identified from the sputa or throat swab specimens of tuberculosis patients.M.tuberculosis strains resistance to PAS was determined by the proportional method,and their thyA gene mutation was detected by PCR-DNA sequencing.Results Of 96 M.tuberculosis isolates,65 were PAS-sensitive,and 31 were PAS-resistant.Using M.tuberculosis H37Rv as a control,the thyA gene mutation rate in PAS-sensitive and PAS-resistant strains of M.tuberculosis were 46.15%(30/65) and 70.97%(22/31),respectively.Most of stains showed single base deletion and insertion mutations,in which C deletion at codon 19 and codon 168 were 54.84%(17/31),25.81%(8/31) in PAS-resistant stains respectively,and 35.38%(23/65) and 12.31%(8/65) in PAS-sensitive strains respectively.Conclusion The frequency of the thyA gene mutation in PAS-resistant strains was significantly higher than that in PAS-sensitive strains.The thyA gene could be a potential target for the development of PAS resistance.But there were not any site with specific mutation found in this study.

Objective To understand the condition of the second-line drug susceptibility testing in multidrug-resistant tuberculosis(MDR-TB) patients in Binzhou city from 2009 to 2011 and to provide evidences for making the treatment regimens.Methods The absolute concentration method was used in drug susceptibility testing with 4 kind of second-line anti-TB drug in 41 confirmed MDR-TB cases.Results In 41 MDR-TB cases,14.6% was resistant to KM,9.8% was resistant to AMK,7.3% was resistant to LFX and 4.9% was resistant to CPM.65.9% of the MDR-TB strains were sensitive to the 4 kind of second-line anti-TB drugs,and XDR-TB accounted for 2.4%.Conclusions The second-line anti-TB drug susceptibility testing will help us to make the standard individual treatment regimens for the MDR-TB patients.

Objective To evaluate the clinical application value of detecting the Mycobacterium tuberculosis and non-tuberculous mycobacteria(NTM) by PCR-fluorescent probe. Methods 1015 sputum specimens and 56 clinical isolates were studied using PCR-fluorescent probe of Capital Bio Corporation.And the results were compared with that of Mycobacterium tuberculosis detection kit of Daan Company. Results The sensitivity and specificity of detecting Mycobacteria in the sputum specimens by PCR-fluorescent probe were 50.3%(373/741) and 98.9%(271/274) respectively,in which the sensitivities for smear-positive and smear-negative pulmonary tuberculosis were 97.0%(257/265) and 24.4%(116/476) respectively.Of 1015 sputum specimens,11(1.1%)were detected as NTM,Using 16S rDNA sequencing as control,the accuracy rate was 100.0%.138 sputum specimens were detected repeatedly,the coincidence rate was 100.0%.Of 56 clinical isolates,1 strain was detected as Mycobacterium tuberculosis and 55 were detected as NTM,the accuracy rate was also 100.0%.The total coincidence rate of 226 sputum specimens was 95.1%(215/226) compared with Mycobacterium tuberculosis detection kit of Daan Company.There were no significant difference between two methods(χ2=2.98,P=0.226). Conclusion PCR-fluorescent probe can rapidly detect and differentiate Mycobacterium tuberculosis and NTM,have the value of clinical application.

Objective To evaluate the clinical diagnostic value of real-time FQ-PCR assay for the detection of Mycobacterium tuberculosis(MTB)/non-tuberculous mycobacteria(NTM). Methods 420 specimens were detected by real-time FQ-PCR,and the results were compared with those of AFB smear and culture. Results The sensitivity of FQ-PCR was 48.5%,in which the sensitivity in bacterium-positive and bacterium-negative specimens were 95.8% and 14.5%,respectively.The specificity,positive predictive value and negative predictive value of FQ-PCR were 99.3%,99.1% and 55.5%,respectively.1 of 388 sputum specimens was NTM-positive by FQ-PCR,which was confirmed by DNA sequencing.32 NTM isolates were confirmed by FQ-PCR and DNA sequencing.Their accuracy was 100%. Conclusions The real-time FQ-PCR was a simple,rapid and specific assay for the detection of Mycobacterium tuberculosis/non-tuberculous mycobacteria in a sealed tube.

患者男,19岁,因间断发热3个月,发现HIV抗体阳性3d于2010年7月16日人院.患者3个月前无明显诱因出现发热,体温最高达39℃,在当地诊所对症治疗,效果不佳.2周前在外院就诊,考虑合并结核感染可能性大,予利福平、毗嗪酞胺、乙胺丁醇治疗,体温仍波动于38.0～39.5℃.3d前发现HIV抗体阳性,故转人我院.

Objective To discuss the application of rotary fluorescent quantitative PCR instrument in clinical detection of M. tuberculosis. Methods 1 132 clinical isolated strains were tested by rotary fluorescent quantitative PCR(FQ-PCR) for strain identification and quantitative analysis and specimens were examined microscopically with Ziehl -Neelsen staining and cultured at the same time. Results Total positive detection rate was 48.6% and positive detection rate 96.56%(253/262) in positive acid fast stain with negative coincidence 77.85% (369/474). Coincidence of strain identification was 100% . Conclusion Using rotary FQ-PCR instrument with supporting reagent can effectively identify Mycobacterium tuberculosis complex and diagnose tuberculosis.

Objective To develop an improved minimum inhibitory concentration (IMIC) test to detect drug-resistant Mycobacterium tuberculosis clinical isolates. Methods 135 clinical isolates detected the drug susceptibility using traditional proportional method were retested and verified their sensitivity to isoniazid (INH),rifampin (RFP),ethambutol (EMB),streptomycin (SM) and ofloxacin (OFLX) by IMIC test. Results In the tubes with same drug concentration,68.89% of 135 clinical isolates with 1×107/ml bacterium number inoculated got the same results as those with 1×105/ml bacterium number inoculated,and 31.1% was inconsistent. 14.8% (20/135) of the isolates (including 1 RFP-resistant,3 INH-resistant,3 OFLX-resistant,5 EMB-resistant and 8 SM-resistant strains) were judged the results from negative to positive. Conclusions The improved minimum inhibitory concentration test could increase positive detectable rate of drug-resistant Mycobacterium tuberculosis,and find more potential drug-resistant TB patients.

Objective To evaluate the effect of MTBDRplus assay in rapid detection of resistance to rifampin(RIF) and isoniazid(INH) in Mycobacterium tuberculosis clinical isolates collected in Beijing.Methods A total of 169 clinical isolates were enrolled in the study.Using the tranditional drug susceptibility testing as the control,the sensitivity and specificity of the MTBDRplus assay and the variety of gene mutations were assessed.Results The sensitivity and specificity of MTBDRplus assay for the detection of RIF and INH resistance were 96.9%,85.3% and 93.2%,98.1%,respectively.The S531L mutation of rpoB was the most frequent(55.2%),followed by mutations D516V(8.3%),H526Y(7.3%) and H526D(3.1%).The frequent mutations of katG gene and inhA promoter region were S315T1(62.9%) and C15T(21.6%) in INH-resistant isolates,respectively.Conclusion The MTBDRplus assay is a sensitive,specific and rapid tool for the diagnosis of RIF,INH resistance and multi-drug resistance in clinical isolates.