结核分枝杆菌重要诊断用抗原研究进展

血清学试验是结核诊断的重要依据。随着科学技术的进步,新的结核诊断用抗原不断被发现。我们简要综述了结核菌素蛋白衍生物、抗原85复合体、38kDa磷酸盐转运蛋白、6kDa早期分泌性蛋白、10kDa培养滤液蛋白、免疫性蛋白MPT64、主要分泌性免疫蛋白MPB70、表面脂蛋白MPB83等8种结核分枝杆菌重要抗原作为结核诊断用抗原的研究进展。     

Rapid Detection of Mycobacterium tuberculosis by Recombinase Polymerase Amplification

Improved access to effective tests for diagnosing tuberculosis (TB) has been designated a public health priority by the World Health Organisation. In high burden TB countries nucleic acid based TB tests have been restricted to centralised laboratories and specialised research settings. Requirements such as a constant electrical supply, air conditioning and skilled, computer literate operators prevent implementation of such tests in many settings. Isothermal DNA amplification technologies permit the use of simpler, less energy intensive detection platforms more suited to low resource settings that allow the accurate diagnosis of a disease within a short timeframe. Recombinase Polymerase Amplification (RPA) is a rapid, low temperature isothermal DNA amplification reaction. We report here RPA-based detection of Mycobacterium tuberculosis complex (MTC) DNA in <20 minutes at 39°C. Assays for two MTC specific targets were investigated, IS6110 and IS1081. When testing purified MTC genomic DNA, limits of detection of 6.25 fg (IS6110) and 20 fg (IS1081)were consistently achieved. When testing a convenience sample of pulmonary specimens from suspected TB patients, RPA demonstrated superior accuracy to indirect fluorescence microscopy. Compared to culture, sensitivities for the IS1081 RPA and microscopy were 91.4% (95%CI: 85, 97.9) and 86.1% (95%CI: 78.1, 94.1) respectively (n = 71). Specificities were 100% and 88.6% (95% CI: 80.8, 96.1) respectively. For the IS6110 RPA and microscopy sensitivities of 87.5% (95%CI: 81.7, 93.2) and 70.8% (95%CI: 62.9, 78.7) were obtained (n = 90). Specificities were 95.4 (95% CI: 92.3,98.1) and 88% (95% CI: 83.6, 92.4) respectively. The superior specificity of RPA for detecting tuberculosis was due to the reduced ability of fluorescence microscopy to distinguish Mtb complex from other acid fast bacteria. The rapid nature of the RPA assay and its low energy requirement compared to other amplification technologies suggest RPA-based TB assays could be of use for integration into a point-of-care test for use in resource constrained settings.     

人型结核杆菌全染色体DNA探针鉴别结核杆菌和其安分枝杆菌

The dot-blots containing DNA isolated from nonmycobacterial and mycobacterial microorganisms were hybridized with 32P-labeled M. tuberculosis whole chromosomal DNA at the various temperatures. The probe did not cross-hybridize to DNA of nonmycobacterial microorganisms (E. coli, Plasmid pUC19, Nocardia asteriodes), nor with DNA from all mycobacteria tested except M. bovis BCG under the higher temperature conditions. Microorganisms could also be directly spotted and lysed on nitrocellulose filters and used for hybridization thus making this technique suitable for clinical diagnosis.     

Radioactive Bromide Partition Test in Differential Diagnosis of Tuberculous Meningitis

In 19 cases of lymphocytic meningitis, the radioactive bromide partition test showed that four were tuberculous and 15 viral in origin. In all the tuberculous cases the serum/cerebrospinal fluid bromide ratio was below a critical value of 1·6, and in all the cases of viral meningitis the ratio was above this value. The test may be particularly helpful when diagnosis is difficult. The test may prove to be a valuable and justified additional procedure in the early diagnosis of tuberculous meningitis.     

聚合酶链式反应检测结核杆菌的研究

以人型结核杆菌基因组DNA为模板,合成二段引物各20个碱基进行聚合酶链式反应(PCR)。经琼脂糖凝胶电泳证实,获得一条245bp扩增带。PCR检测的敏感性染色体基因组DNA为1pg,菌悬液为13个活菌／ml。在特异性试验中,人型结核杆趋,牛型结核杆菌、BCG可见此扩增带。被试的其它14种扰酸菌以及变铅青链霉菌、大肠杆菌质粒Puc19、星状诺卡氏菌、红球菌均未见该扩增带。54例肺结核痰标本3种方法检查的阳性率分别为：萋尼氏抗酸染色16．7％,培养法14．8％,PCR 37．0％。前2种检查方法分别与PCR比较,经统计学处理均有显著性差异(P<0．01)。12例非结核性肺部疾患痰标本抗酸染色和PCR均为阴性。结果表明,PCR技术是快速、敏感、特异诊断结核病的方法。     

Disruption of response regulator gene, devR, leads to attenuation in virulence of Mycobacterium tuberculosis

The devR-devS two-component system of Mycobacterium tuberculosis was identified earlier and partially characterized in our laboratory. A devR::kan mutant of M. tuberculosis was constructed by allelic exchange. The devR mutant strain showed reduced cell-to-cell adherence in comparison to the parental strain in laboratory culture media. This phenotype was reversed on complementation with a wild-type copy of devR. The devR mutant and parental strains grew at equivalent rates within human monocytes either in the absence or in the presence of lymphocytic cells. The expression of DevR was not modulated upon entry of M. tuberculosis into human monocytes. However, guinea pigs infected with the mutant strain showed a significant decrease in gross lesions in lung, liver and spleen; only mild pathological changes in liver and lung; and a nearly 3 log lower bacterial burden in spleen compared to guinea pigs infected with the parental strain. Our results suggest that DevR is required for virulence in guinea pigs but is not essential for entry, survival and multiplication of M. tuberculosis within human monocytes in vitro. The attenuation in virulence of the devR mutant in guinea pigs together with DevR-DevS being a bona fide signal transduction system indicates that DevR plays a critical and regulatory role in the adaptation and survival of M. tuberculosis within tissues.     

Rapid Diagnosis and Simultaneous Identification of Tuberculous and Bacterial Meningitis by a Newly Developed Duplex Polymerase Chain Reaction

The present study describes the development and evaluation of a duplex polymerase chain reaction (D-PCR) for diagnosis and simultaneous identification of tuberculous meningitis (TBM) and bacterial meningitis (BM) in a single reaction. A D-PCR with primers amplifying portions of the Mycobacterium tuberculosis IS6110 and the eubacteria 16SrDNA sequence in a same reaction mix was developed and tested on DNA extracted from 150 clinical CSF samples from different categories (TBM = 39, BM = 26, control infectious and non-infectious category = 85). The results indicate a clear differentiation between bands for eubacteria and M. tuberculosis with an analytical sensitivity of 10³ cfu/ml for eubacteria and 10² cfu/ml for M. tuberculosis. When evaluated in clinical samples, D-PCR overall diagnosed 100 % confirmed TBM and 100 % confirmed BM cases with overall specificity of 96.5 %. D-PCR can be an effective tool for diagnosis and simultaneous identification of TBM or BM in a single PCR reaction. It saves time, cost, labour and sample amount and help in administration of appropriate antimicrobial therapy. The proposed diagnostic assay would be helpful in correct and rapid management of TBM and BM patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s12088-015-0517-9) contains supplementary material, which is available to authorized users.     

The use of Mycobacterium tuberculosis HspX and GlcB proteins to identify latent tuberculosis in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is an autoimmune disease characterised by the destruction of articular cartilage and bone damage. The chronic treatment of RA patients causes a higher susceptibility to infectious diseases such as tuberculosis (TB); one-third of the world’s population is latently infected (LTBI) with Mycobacterium tuberculosis (Mtb). The tuberculin skin test is used to identify individuals LTBI, but many studies have shown that this test is not suitable for RA patients. The goal of this work was to test the specific cellular immune responses to the Mtb malate synthase (GlcB) and heat shock protein X (HspX) antigens of RA patients and to correlate those responses with LTBI status. The T-helper (Th)1, Th17 and Treg-specific immune responses to the GlcB and HspX Mtb antigens were analysed in RA patients candidates for tumour necrosis factor-α blocker treatment. Our results demonstrated that LTBI RA patients had Th1-specific immune responses to GlcB and HspX. Patients were followed up over two years and 14.3% developed active TB. After the development of active TB, RA patients had increased numbers of Th17 and Treg cells, similar to TB patients. These results demonstrate that a GlcB and HspX antigen assay can be used as a diagnostic test to identify LTBI RA patients.     

应用膜反向斑点杂交技术快速检测结核分支杆菌耐乙胺丁醇基因型的研究

应用膜反向斑点杂交技术快速检测结核分支杆菌对乙胺丁醇（EMB）耐药性。设计与合成用于检测结核分支杆菌耐EMB基因embB的寡核苷酸探针,点于硝酸纤维素膜上,与结核分支杆菌临床分离株生物素标记的聚合酶链反应（PCR）产物进行反向斑点杂交,并与PCR单链构象多态性（PCRSSCP）和PCR直接测序（PCRDS）结果比较。对81株结核分支杆菌临床分离株进行分析,31株EMB敏感株中,26株embB基因的SSCP图谱、膜反向斑点杂交结果与标准株(H37Rv)完全相同;其余5株SSCP图谱出现泳动变位,其中3株E1b杂交阳性,PCRDS分析为embB基因306位密码子ATG→GTG突变;2株E1d杂交阳性,PCRDS分析为embB基因306位密码子ATG→ATA突变。50株耐EMB菌株中,24株PCRSSCP 图谱与标准菌株相同,E1杂交阳性;26株PCRSSCP图谱出现泳动变位,其中18株E1b杂交阳性,2株E1c杂交阳性,5株E1d杂交阳性,1株E1e杂交阳性,未发现E1f杂交阳性,与PCRSSCP、PCRDS分析结果一致。突变检出率为52%。 膜反向斑点杂交技术可能成为检测部分结核分支杆菌乙胺丁醇耐药基因型简便、快速的方法。     

头颅CT、头颅MRI 在结核性脑膜炎诊断中应用

结核性脑膜炎是中枢神经系统感染性疾病中常见病,且致死率、致残率都很高.结核性脑膜炎的临床表现具有非特异性性,因此临床上容易引起误诊、漏诊.目前结核性脑膜炎的诊断主要是依据临床资料,脑脊液检查、生化及病原学和影像学检查等综合诊断方法.早期诊断及治疗和结核性脑膜炎的预后有着密切的关系,提高早期诊断是改善结核性脑膜炎顸后关键.头颅CT、头颅MR在结核性脑膜炎诊断中有着重要的作用,对结核性脑膜炎的诊断可提供重要的价值.本文就头颅CT及头颅MR在结核性脑膜炎中的作用做一综述.     

结核分枝杆菌诊断技术研究进展

近年来,结核病的诊断方法逐渐得到完善,将传统细菌学检验方法、免疫学方法和分子生物学的方法相结合,加速了对结核病的诊断研究。特别是分子生物学技术的发展,对于阐明分枝杆菌和结核分枝杆菌的遗传变异规律及分子进化等都有重要的意义。我们结合近年来结核分枝杆菌诊断在免疫学检测、PCR技术、基因技术等方面的进步,从细菌学检测、免疫学检测、分子生物学检测等3个方面做简要综述。     

PCR法快速检测临床标本中结核杆菌DNA

应用聚合酶链反应（ＰＣＲ）快速检测临床标本（脑脊液、胸水、腹水、血、痰液）中的结核杆菌ＤＮＡ,特异性扩增片段１２３ｂｐ,为结核杆菌的特异性重复序列ＩＳ６１１０部分基因。ＰＣＲ检测人型结核杆菌的敏感性达１０ｆｇＤＮＡ。临床标本的ＰＣＲ检测阳性率（２３．３％）明显高于抗酸染色涂片（２．９％）和细菌培养（５．７％）的阳性率（Ｐ〈０．０５）。通过设立对照系统及对扩增产物酶切分析,表明该法无假阴性结果（特异     

分枝杆菌RpsI序列差异对核糖体结构与功能的影响

核糖体结构存在动态调控,其变化与细菌发育、环境适应等过程密切相关。使用NCBI BLAST比对结核分枝杆菌(Mycobacterium tuberculosis)核糖体蛋白RpsI、RpmI和RpmJ与耻垢分枝杆菌(Mycobacterium smegmatis)相应蛋白的氨基酸序列,发现RpsI N端氨基酸序列存在较大差异。为了探究该N端序列差异对核糖体结构与功能的影响,将表达有结核分枝杆菌rpsI基因(rpsI_Rv)的质粒整合至耻垢分枝杆菌基因组中,并利用同源重组的方法敲除耻垢分枝杆菌rpsI基因,以此构建重组菌株。聚合酶链反应(polymerase chain reaction,PCR)结果表明该重组菌株构建成功。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)显示0.5 mmol/L异丙基-β-D-硫代半乳糖苷(IPTG)于16 ℃可诱导表达RpsI_Rv。用纯化的RpsI_Rv制备特异性多克隆抗体,其效价为 1 600 000。反转录PCR 和蛋白质印迹法(Western blot)显示rpsI_Rv在重组菌株中成功表达。测定重组菌株与空载对照菌株在不同温度下的生长曲线,该重组菌株在不同温度下的生长速率未发生改变。采用通用液体倍比稀释法测定作用于核糖体不同位点的5种抗生素最小抑菌浓度(MIC₉₀),重组菌株对阿米卡星(作用于核糖体小亚基A位点的抗生素)的敏感性升高,提示分枝杆菌RpsI序列差异导致核糖体小亚基A位点附近的结构发生改变,这为分枝杆菌核糖体结构与功能的机制研究提供了数据。     

Locked Nucleic Acid Probe-Based Real-Time PCR Assay for the Rapid Detection of Rifampin-Resistant Mycobacterium tuberculosis

Drug-resistant Mycobacterium tuberculosis can be rapidly diagnosed through nucleic acid amplification techniques by analyzing the variations in the associated gene sequences. In the present study, a locked nucleic acid (LNA) probe-based real-time PCR assay was developed to identify the mutations in the rpoB gene associated with rifampin (RFP) resistance in M. tuberculosis. Six LNA probes with the discrimination capability of one-base mismatch were designed to monitor the 23 most frequent rpoB mutations. The target mutations were identified using the probes in a “probe dropout” manner (quantification cycle = 0); thus, the proposed technique exhibited superiority in mutation detection. The LNA probe-based real-time PCR assay was developed in a two-tube format with three LNA probes and one internal amplification control probe in each tube. The assay showed excellent specificity to M. tuberculosis with or without RFP resistance by evaluating 12 strains of common non-tuberculosis mycobacteria. The limit of detection of M. tuberculosis was 10 genomic equivalents (GE)/reaction by further introducing a nested PCR method. In a blind validation of 154 clinical mycobacterium isolates, 142/142 (100%) were correctly detected through the assay. Of these isolates, 88/88 (100%) were determined as RFP susceptible and 52/54 (96.3%) were characterized as RFP resistant. Two unrecognized RFP-resistant strains were sequenced and were found to contain mutations outside the range of the 23 mutation targets. In conclusion, this study established a sensitive, accurate, and low-cost LNA probe-based assay suitable for a four-multiplexing real-time PCR instrument. The proposed method can be used to diagnose RFP-resistant tuberculosis in clinical laboratories.     

Amplicon DNA Melting Analysis for the Simultaneous Detection of Brucella spp and Mycobacterium tuberculosis Complex. Potential Use in Rapid Differential Diagnosis between Extrapulmonary Tuberculosis and Focal Complications of Brucellosis

Some sites of extrapulmonary tuberculosis and focal complications of brucellosis are very difficult to differentiate clinically, radiologically, and even histopathologically. Conventional microbiological methods for the diagnosis of extrapulmonary tuberculosis and complicated brucellosis not only lack adequate sensitivity, they are also time consuming, which could lead to an unfavourable prognosis. The aim of this work was to develop a multiplex real-time PCR assay based on SYBR Green I to simultaneously detect Brucella spp and Mycobacterium tuberculosis complex and evaluate the efficacy of the technique with different candidate genes. The IS711, bcsp31 and omp2a genes were used for the identification of Brucella spp and the IS6110, senX3-regX3 and cfp31 genes were targeted for the detection of the M. tuberculosis complex. As a result of the different combinations of primers, nine different reactions were evaluated. A test was defined as positive only when the gene combinations were capable of co-amplifying both pathogens in a single reaction tube and showed distinguishable melting temperatures for each microorganism. According to the melting analysis, only three combinations of amplicons (senX3-regX3+bcsp31, senX3-regX3+IS711 and IS6110+IS711) were visible. Detection limits of senX3-regX3+bcsp31 and senX3-regX3+IS711 were of 2 and 3 genome equivalents for M. tuberculosis complex and Brucella while for IS6110+IS711 they were of 200 and 300 genome equivalents, respectively. The three assays correctly identified all the samples, showing negative results for the control patients. The presence of multicopy elements and GC content were the components most influencing the efficiency of the test; this should be taken into account when designing a multiplex-based SYBR Green I assay. In conclusion, multiplex real time PCR assays based on the targets senX3-regX3+bcsp31 and senX3-regX3+IS711 using SYBR Green I are highly sensitive and reproducible. This may therefore be a practical approach for the rapid differential diagnosis between extrapulmonary tuberculosis and complicated brucellosis.