石蜡包埋组织实时荧光定量聚合酶链反应检测在结核病诊断中的价值

目的探讨石蜡包埋组织实时荧光定量聚合酶链反应(FQ-PCR)检测结核分枝杆菌DNA在结核病诊断中的价值。方法275例组织标本行常规组织病理学检查、抗酸染色,并对石蜡包埋组织应用实时荧光定量聚合酶链反应检测结核分枝杆菌DNA。结果275例FQ-PCR检测结核分枝杆菌DNA阳性211例(76.7%),病理诊断为结核183例(66.5%),抗酸染色阳性23例(8.4%)。病理诊断为结核者FQ-PCR阳性率为93.4%,抗酸染色阳性者FQ-PCR阳性率95.7%。结论实时荧光聚合酶链反应技术敏感性高、其与组织病理学相结合可以提高诊断率。     

γ干扰素释放试验在肺结核和非结核分枝杆菌肺病鉴别诊断中的应用价值

目的 探讨结核分枝杆菌特异性γ干扰素释放试验（interferon gamma release assays,IGRAs）在鉴别诊断肺结核和非结核分枝杆菌（non-tuberculous mycobacteria,NTM）肺病中的应用价值.方法 选择深圳市第三人民医院2011年1月至2013年5月334例收住于肺科住院部感染了分枝杆菌的肺病患者.采用反向斑点杂交技术对334例分枝杆菌感染的肺病患者痰培养分离的分枝杆菌进行菌种鉴定;采用IGRAs测定患者外周血结核分枝杆菌抗原特异性γ干扰素（IFN-γ）应答;采用结核分枝杆菌特异性荧光定量PCR技术检测痰标本中结核分枝杆菌DNA.结果 在334例分枝杆菌感染的患者中,240例的菌株为结核分枝杆菌,94例为NTM; 240例肺结核患者中痰结核分枝杆菌DNA PCR检测阳性率为74.58％（179/240）,IGRAs检测阳性率为77.08％（185/240）;94例NTM肺病患者中,结核分枝杆菌DNA PCR检测阳性率为10.64％（10/94）,IGRAs检测阳性率为20.21％（19/94）.结核分枝杆菌DNA PCR和IGRAs检测鉴别诊断肺结核和NTM肺病的敏感度分别为74.58％（179/240）、77.08％（185/240）,特异度分别为89.36％（84/94）、79.79％（75/94）;两种方法联合检测肺结核的敏感度为%.75％（225/240）、特异度为77.66％（73/94）.结论 IGRAs对于鉴别肺结核和NTM肺病具有较好的应用价值,联合应用结核分枝杆菌DNA PCR和IGRAs可以显著增加鉴别诊断的准确性,对于早期抗结核药物的选择具有重要的指导意义.     

血结核抗体和结核DNA联合检测对肺外结核的诊断价值

目的 肺外结核占结核病的比例较低，且部位广泛，不易获得细菌学证据，对此，采用查抗体和DNA，探讨诊断价值。方法 对肺外结核l15例采用血清TBAb血单个核细胞TBDNA联合检测。结果 肺外结核组：血抗PPD—IgG和PCR TB DNA联合检测累计阳性108例，阳性率93．9％；对照组：血抗PPD—IgG和PCR TB DNA联合检测累计阳性12例，阳性率10．7％。结论 血结核抗体和结核DNA联合检测能为肺外结核诊断提供线索。     

猴源性结核分枝杆菌的分离和鉴定

目的探讨非人灵长类结核病的诊断方法，以及进行结核病的病原学的调查研究。方法利用病理学诊断方法，微生物分离方法以及分子生物学技术对结核菌素阳性的4只恒河猴，1只食蟹猴进行疾病诊断和病原分离。结果5只猴尸检，出现典型的干酪样病变；病变组织切片，显微镜检，可见典型的结核病特征。利用米氏7H9培养基和改良罗氏培养基进行病原分离，通过TCH和PNB等培养基进行生化鉴定，确认所分离的分枝杆菌是结核分枝杆菌；巢式PCR对石蜡包埋的病变组织抽提的DNA进行扩增，5只猴的DNA样品都扩增出结核分枝杆菌特异的123bp片段，证实感染猴的病变组织中含有结核分枝杆菌。结论非人灵长类死后，结核病的诊断可以通过常规的病理和微生物分离诊断方法进行。分子生物学技术在结核病的诊断中的应用逐渐成为必不可少的诊断方法，它将有利于对病理学诊断、病原分离困难的小的病变组织的诊断，以及对病原分离过程中分枝杆菌污染的判定。     

结核分枝杆菌Ag85A／ESAT-6嵌合型质粒DNA疫苗和抗结核药物联合治疗小鼠耐药结核病的效果研究

目的研究结核分枝杆菌Ag85A／ESAT-6嵌合型质粒DNA疫苗和抗结核药物联合治疗小鼠耐药结核病的效果。方法用结核分枝杆菌高耐利福平低耐异烟肼临床分离株HB240尾静脉注射BALB／c小鼠1个月后，将小鼠随机分成2组，第1组用利福平（RFP）、异烟肼（INH）治疗12周，第2组用RFP、INH和结核分枝杆菌Ag85A／ESAT-6嵌合型质粒DNA疫苗（免疫5次）联合治疗12周；治疗结束后4和8周，分别取肺、肝和脾观察病理改变、称取质量、作菌落计数。结果治疗结束后4和8周，第2组小鼠体质量均超过第1组，但无显著性差异（P〉0．05）。治疗结束后4周，第2组肺、脾脏指数（0．017，0．011）均略低于第1组（0，020，0，012）（P〉0．05）；治疗结束后8周，第2组肺、肝脏指数（O．021，0．047）均略低于第1组（0．022，0．048）（P〉0．05）；而第2组脾脏指数（0．008）显著低于第1组（0．012）（P〈0．05）。治疗结束后4周，第2组有4例脾脏未见明显病变，第1组仅1例脾脏未见明显病变；治疗结束后8周，第2组有1例肺门淋巴结肿大，而第1组有3例；第2组有5例脾脏未见明显病变，第1组仅2例脾脏未见明显病变。治疗结束后4周，第2组肺菌落计数和脾菌落计数比第1组显著减少，分别减少70％和80％。结论DNA疫苗和抗结核药物联合治疗小鼠耐药结核病疗效高于单纯化疗。     

噬菌体生物扩增法检测尿液结核分枝杆菌对肾结核的诊断价值探讨

目的 利用噬菌体生物扩增法检测尿液结核分枝杆菌,评价其对肾结核诊断价值。 方法 对肾结核患者63例应用涂片抗酸染色法检测结核分枝杆菌、结核分枝杆菌培养、噬菌体生物扩增法进行尿液结核分枝杆菌检测,聚合酶链反应法检测结核菌DNA。同时选正常人群21人作为对照组行尿液噬菌体生物扩增法检测结核分枝杆菌,聚合酶链反应法检测结核分枝杆菌DNA。结果 肾结核患者尿液行噬菌体生物扩增法检测结核分枝杆菌阳性率明显高于涂片抗酸染色法检测结核分枝杆菌及结核分枝杆菌培养（P<0.01）。与PCR法比较差异无统计学意义（P>0.05）,噬菌体生物扩增法检测尿液中结核分枝杆菌对肾结核诊断有较高的特异度(95.2%)和灵敏度(69.8%)。 结论 噬菌体生物扩增方法检测尿液结核分枝杆菌对肾结核诊断具有重要的参考价值。     

巢式实时荧光定量聚合酶链反应检测结核分枝杆菌DNA的临床应用

目的探讨巢式实时荧光定量PCR（QNRT-PCR）检测结核分枝杆菌（MTB）DNA的临床价值。方法应用SYBR Green I建立检测结核分枝杆菌MTP64基因的QNRT—PCR方法,分别检测24份肺结核患者痰液,27份结核性胸膜炎患者胸水,以及对照组75份痰液和胸水的MTBDNA含量。结果以培养为金标准,QNRT—PCR敏感性、特异性、阳性预测值（PPV）、阴性预测值（NPV）分别为95．83％、61．54％、69．70％和94．12％,结核性胸膜炎的阳性率为70．37％。三种PCR方法阳性率比较,差异具有统计学意义（P〈0．05）,QNRT—PCR与实时荧光定量PCR拷贝数配对检验差异没有统计学意义（P〉0．05）,QNRT—PCR与实时荧光定量PCR的Cr值配对检验差异具有统计学意义（P〈0．01）。结论QNRT—PCR方法可检测痰液和胸水MTB DNA,对含微量MTB DNA样本的高敏感性在结核病的早期诊断中有重要参考价值。     

颗粒溶素和白细胞介素12重组耻垢分枝杆菌对小鼠结核病的治疗作用

目的 探讨携带编码人天然颗粒溶素和小鼠白细胞介素12（IL-12）基因质粒（pZM03）的重组耻垢分枝杆菌对结核分枝杆菌感染的疗效与机制。方法 结核分枝杆菌H37Rv感染Balb／c小鼠4周后，分别用生理盐水、耻垢分枝杆菌、pZM03、重组耻垢分枝杆菌治疗6次，于第1次治疗后3个月处死小鼠，检测器官荷菌量、脾淋巴细胞γ干扰素的分泌水平、血清IL-12和IgG2a分泌水平和肺、脾组织中颗粒溶素表达，同时观察小鼠肺、脾组织病理改变情况。结果 重组耻垢分枝治疗组的肺和脾组织对数荷菌量分别为（4.57±0．28）和（3．47±0．25）CFU／g，比生理盐水组的（5．77±0．12）和（4．66±0．18）CFU／g、载体组的（5．62±0．14）和（4．65±0．26）CFU／g及质粒组的（5．04±0．22）和（4．25±0．48）显著降低；重组耻垢分枝杆菌组和pZM03组经结核菌素纯蛋白衍生物刺激后，1干扰素分泌水平显著高于耻垢分枝杆菌组和生理盐水对照组；重组耻垢分枝杆菌组血清IL-12水平和IgG2a水平显著高于耻垢分枝杆菌组和生理盐水对照组。用免疫组织化学方法检测到小鼠肺及脾组织中颗粒溶素的表达。生理盐水和耻垢分枝杆菌组的肺组织病理改变以渗出为主，病变广泛，增生改变不明显；重组耻垢分枝杆菌组的病变范围局限，并有类上皮细胞和泡沫细胞。治疗组和对照组的脾脏病理改变不明显。结论 携带颗粒溶素和IL-12的重组耻垢分枝杆菌对小鼠结核病有一定的免疫治疗作用，与增强宿主Th1型免疫应答和颗粒溶素的抗菌活性有关。     

二聚体蝎型探针荧光定量PCR快速检测临床标本结核分枝杆菌DNA

目的比较二聚体蝎型探针荧光定量PCR与抗酸染色、L-J培养法、结核分枝杆菌直接试验（MTD）的检出率、检测时间等，探讨二聚体蝎型探针荧光定量PCR检测临床标本中结核分枝杆菌DNA（T＆DNA）的实际应用价值。方法以建立的结核二聚体蝎型探针荧光定量PCR方法为基础，对43例结核确诊患者的标本及11例非肺结核患者的痰标本进行检测，并与抗酸染色、L-J培养法、结核分枝杆菌直接试验（MTD）进行比较。结果二聚体蝎型探针荧光定量PCR能快速准确的检测临床标本中的TB-DNA。其标准品浓度在10^2～10^6copies／μl时，方法能够保持良好的线性关系（相关系数为0．9994），阳性检出率（100％）显著高于抗酸染色法（16．28％）和培养法（37．21％）的检出率，与MTD试验的检出率（100％）一致。MTD试验检测时间约4～5h，而二聚体蝎型探针FQ-PCR检测约需80min即可得到检测结果，检测费用仅为MTD的1／4。结论二聚体蝎型探针荧光定量PCR用于临床标本结核分枝杆菌DNA的检测具有快速价廉、敏感特异的特点，该方法作为定量检测结核分枝杆菌的分子诊断新途径值得临床推广应用。     

荧光定量聚合酶链反应检测肺结核和非典型分枝菌肺病的结果分析

目的了解荧光定量聚合酶链反应（FQ—PCR）技术检测在临床工作中对结核分枝杆菌检测的敏感性和特异性,鉴别结核分枝杆菌和非典型分枝杆菌。方法留取病者痰液行FQ—PCR检测及抗酸杆菌培养鉴定。结果FQ-PCR监测结核病组阳性率52．5％,而非典型分枝杆菌肺病组也有12．5％阳性率,经χ^2检查P〈0．01,两者差异显著。结论FQ—PCR检测对于鉴别结核分枝杆菌和非典型分枝杆菌有一定的意义,但在临床工作中的敏感性和特异性有待提高。     

Extrapulmonary Locations of Mycobacterium tuberculosis DNA During Latent Infection

Background.?One-third of the world's population has latent infection with Mycobacterium tuberculosis, and 10%-15% of cases of reactivation occur at extrapulmonary sites without active pulmonary tuberculosis. Methods.?To establish the frequency and location of mycobacterial DNA, organ specimens from 49 individuals who died from causes other than tuberculosis were studied by means of polymerase chain reaction (PCR), PCR plus DNA hybridization, in situ PCR, real-time PCR, and spoligotyping. Results.?Lung specimens from most subjects (36) were positive for M. tuberculosis, as were specimens from the spleen (from 35 subjects), kidney (from 34), and liver (from 33). By in situ PCR, mycobacterial DNA was found in endothelium, pneumocytes, and macrophages from the lung and in Bowman's parietal cells and convoluted proximal tubules from the kidney. In spleen, macrophages and sinusoidal endothelial cells were positive, whereas in liver, Kupffer cells and sinusoidal endothelium were commonly positive. Spoligotyping of 54 pulmonary and extrapulmonary positive tissues from 30 subjects showed 43 different genotypes, including 36 orphan types. To confirm the viability of mycobacteria, 10 positive tissue samples were selected for isolation of mycobacterial RNA. All samples showed 16S ribosomal RNA expression, while 8 and 4 samples showed expression of the latent infection genes encoding isocitrate lyase and α-crystallin, respectively. Conclusions.?M. tuberculosis persists in several sites and cell types that might constitute reservoirs that can reactivate infection, producing extrapulmonary tuberculosis without lung involvement.     

High prevalence of Mycobacterium tuberculosis DNA in biopsies from sarcoidosis patients from Catalonia, Spain

BACKGROUND: Sarcoidosis is a systemic granulomatous disease of unknown etiology. The presence of mycobacterial nucleic acid components in patients with sarcoidosis has been demonstrated with varying degrees of success. OBJECTIVES: The aim of this study was to estimate the presence of Mycobacterium tuberculosis DNA in tissues from sarcoidosis patients, in Catalonia, Spain, as well as to assess the long-term clinical course in these patients. METHODS: Fifty-eight paraffin-embedded tissue biopsies corresponding to cases of sarcoidosis (n = 23), lung neoplasm (n = 23), and lung tuberculosis (n = 12) available in 1996 were analyzed in a retrospective study by means of a nested polymerase chain reaction using primers corresponding to the insertion element IS6110 of M. tuberculosis complex. For greater sensitivity, Southern blot hybridization was performed. Clinical data were recorded prior to and after PCR analysis (follow-up reported until 2002). RESULTS: M. tuberculosis DNA was present in 9 out of 23 sarcoidosis biopsies (39%), in 1 out of 23 control patients (4%) (p < 0.01), and in all tissue samples from the 12 control patients with tuberculosis. To date, none of these sarcoidosis patients has developed tuberculosis over a mean (+/-SD) follow-up period of 11 (+/-3.4) years. CONCLUSION: In our setting, M. tuberculosis DNA is present in tissue biopsies of significantly more sarcoidosis patients than controls. However, these results do not demonstrate causality, although they may suggest a link between M. tuberculosis infection and sarcoidosis in some cases. Follow-up of these patients suggests that M. tuberculosis-DNA-positive sarcoidosis patients are not at greater risk of developing tuberculosis than M. tuberculosis-DNA-negative patients.     

A search for mycobacterial DNA in granulomatous tissues from patients with sarcoidosis using the polymerase chain reaction.

We have used the polymerase chain reaction as a tool to detect the presence of mycobacterial DNA from organisms of the Mycobacterium tuberculosis complex and other species of mycobacteria in samples from patients with sarcoidosis. Using systems based on the amplification of a fragment of the gene coding for the 65-kD mycobacterial antigen, which were demonstrated to detect approximately 20 mycobacterial genomes/microgram total DNA, DNA from M. tuberculosis was reproducibly identified in DNA extracted from granulomatous tissues from two patients with sarcoidosis, but could not be detected in DNA extracted from tissue biopsies (n = 16) or cells recovered by lavage (n = 6) from most sarcoid patients or from control subjects (n = 22). Using a system based on the amplification of a fragment of the IS6110 insertion element, which could reliably detect two genomes of mycobacterial DNA/microgram total DNA, no additional positive results were observed. In an effort to identify another species of Mycobacterium present in granulomatous tissues from sarcoid patients but not control tissues, a fragment of the 65-kD mycobacterial antigen was amplified and then reamplified using "nested" primers recognizing sequences that are highly conserved among mycobacteria and closely related species, and the amplified DNA products were cloned and sequenced. Amplified DNA was observed in a minority of samples from patients and control subjects (32/84 and 34/77 attempts, respectively, p greater than 0.2), resulting from amplification of DNA from at least 17 different organisms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Specific detection of Mycobacterium paratuberculosis DNA associated with granulomatous tissue in Crohn's disease.

The role of mycobacteria, specifically Mycobacterium paratuberculosis, in Crohn's disease has aroused considerable controversy for many years. Using the ultra sensitive polymerase chain reaction some studies have reported detection of M paratuberculosis DNA in as many as 65% of Crohn's disease patients but also in patients without disease. Other studies have been negative for both groups. We therefore designed a double blind control trial to investigate the presence of mycobacterial DNA in age, sex, and tissue matched paraffin wax embedded tissues from 31 Crohn's disease tissues, 20 diseased gut control tissues, and 10 ulcerative colitis tissues. The specimens were coded and analysed blind with three separate polymerase chain reactions (PCR) based on DNA sequences specific for M paratuberculosis (IS900), M avium (RFLP type A/1) (IS901), and the Mycobacterium genus (65 kDa gene, TB600). The number of granulomata and presence of acid fast bacilli in each Crohn's disease tissue was also investigated. The sensitivity of the system was determined using similarly prepared gut tissue from an animal infected with M paratuberculosis. Four of 31 Crohn's disease tissues and none of the 30 control and ulcerative colitis derived tissues amplified M paratuberculosis DNA. Crohn's disease tissues containing granulomata were significantly more likely to amplify M paratuberculosis specific DNA on PCR than the non-Crohn's disease tissues (p = 0.02). All the positive Crohn's disease tissues contained granulomata, and none contained acid fast bacilli. Equivalent numbers of Crohn's and non-Crohn's disease tissues amplified the region of the 65 kD gene on PCR for non-specific mycobacterial DNA (11/31 and 9/30 respectively). No sections produced an amplified product with the IS901 PCR. These results suggest that few Crohn's disease gut biopsy sections contain M paratuberculosis DNA in association with granulomata. The absence of such DNA in any control and ulcerative colitic tissue strengthens the case for it having a specific association, which may be pathogenic, with Crohn's disease in this minority of patients.     

Evaluation of polymerase chain reaction for detection of Mycobacterium tuberculosis in pleural fluid

OBJECTIVES: Tuberculosis, a reemergent killer, is threatening to assume serious proportions all over the world, particularly in view of the AIDS pandemic. The detection of mycobacterial DNA by polymerase chain reaction (PCR) in clinical samples is a promising approach for the rapid diagnosis of tuberculous infections. The aims of this study were to evaluate PCR for detection of Mycobacterium tuberculosis in pleural fluids and to correlate the results with adenosine deaminase activity (ADA) estimation and acid-fast bacilli (AFB) screening. METHODS: The sensitivity and specificity of PCR in detection of mycobacterial DNA in 20 samples of tuberculous pleural effusion were evaluated using 40 samples of nontubercular pleural effusion as controls. The results were correlated with the ADA in all 60 pleural fluids. In addition, AFB detection by Ziehl-Neelsen staining on cytospin smears of all pleural fluids was also compared. RESULTS: Of the 20 samples of tuberculous pleural effusion, mycobacterium could be detected by AFB staining in 4 samples. Fourteen samples were PCR positive. None of the samples from the control group were AFB or PCR positive. The sensitivity of PCR, therefore, was 70.0% with specificity of 100% (positive predictive value, 100%; negative predictive value, 86.95%). The sensitivity of AFB screening was at best 20%. The mean of ADA values in tubercular pleural effusions was 63.21 U/L (SD, 33.01), and the mean in the control samples was 51.1 U/L (SD, 29.71). Taking a cut-off value of 50 U/L, both the sensitivity and specificity of ADA estimation in diagnosing tuberculosis were only 55%. CONCLUSION: PCR represents a rapid and sensitive method for the detection of mycobacterial DNA in tuberculous pleural effusions. AFB screening has low sensitivity, and ADA estimation has both low sensitivity and specificity. Therefore, when the clinical suspicion is high and smear result is negative, but the signs and symptoms of M tuberculosis are apparent, PCR is the method of choice for identifying the infection.     

Evaluation of PCR-based methods for the diagnosis of tuberculosis by identification of mycobacterial DNA in urine samples.

SETTING: The Chest Clinic and the JICA (Japan International Cooperation Agency) Molecular Laboratories, University Teaching Hospital, Lusaka, Zambia, and the Department of Internal Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan. OBJECTIVE: To evaluate the polymerase chain reaction (PCR) as a laboratory test for the rapid diagnosis of pulmonary tuberculosis in the African situation by identifying mycobacterial DNA in urine samples using two commonly described molecular methods. DESIGN: Prospective collection and laboratory analysis of urine samples from adult Zambian patients with culture-confirmed pulmonary tuberculosis and healthy controls. METHODS: Urine was obtained from 63 patients with culture-confirmed active pulmonary tuberculosis and 63 'healthy' control patients with no active tuberculosis. DNA was isolated from urine sediment and subjected to analyses by two well-described PCR-based methods, 'the Sechi method' and 'the Githui method', for the identification of Mycobacterium tuberculosis DNA. The sensitivity and specificity of the two tests were determined. RESULTS: The sensitivity and specificity of the Githui method were 55.6% (35/63) and 98.4% (62/63), respectively. The sensitivity and specificity of the Sechi method were 28.6% (18/63) and 98.4% (62/63), respectively. Of the 63 patients, 50 (79%) were HIV sero-positive and the frequency of positive PCR urines using the Githui method was greater in HIV-positive patients than in HIV-negative patients (32/50 = 64% vs. 3/13 = 23%; P = 0.05). CONCLUSIONS: Neither the Githui method nor the Sechi method was sensitive enough to be recommended for routine use in clinical practice. PCR-based assays for the detection of M. tuberculosis DNA in urine will require further refinement before they can be recommended for use in clinical practice in Africa. The presence of mycobacterial DNA in urine samples of patients with pulmonary tuberculosis also requires further study.     

实时荧光PCR检测儿童肺结核粪便中Mtb-DNA的效果评价

目的 应用实时荧光PCR快速检测肺结核患儿粪便中Mtb-DNA,并初步评估其临床效果。 方法 收集肺结核住院儿童粪便标本76份,应用实时荧光PCR检测Mtb-DNA,检测结果与20例其他呼吸系统疾病患儿的粪便实时荧光PCR检测Mtb-DNA、76例粪便抗酸杆菌涂片检查以及41例患儿痰标本的涂片和(或)培养、实时荧光PCR检测结果进行比较。 结果 粪便实时荧光PCR检测敏感度达到23.68%(18/76),特异度为100.00％(20/20),肺结核患儿粪便PCR阳性率［23.68%(18/76)］明显高于涂片阳性率［6.58%(5/76)］,41例患儿中痰涂片和(或)培养阳性例数(15例)和痰PCR检测阳性例数(18例)高于粪便PCR检测阳性例数(11例)。 结论 实时荧光PCR检测儿童粪便Mtb-DNA,是一种特异度高、比较敏感、非侵入性且相对安全的儿童肺结核快速诊断方法。     

Immune responses to mycobacterial antigens in sarcoidosis: a systematic review

From the time sarcoidosis has been described, there has always been a viewpoint that the disease is in some way related to tuberculosis (TB). Sarcoidosis is a granulomatous disease, which is likely a result of continued presentation of a poorly degradable antigen. Mycobacterium tuberculosis has been a very strong contender for this antigen. Besides the molecular studies demonstrating mycobacterial deoxyribonucleic acid (DNA) in the sarcoid tissue, assessment of immune responses against mycobacterial antigens provides a useful tool to study the role of mycobacteria in the pathogenesis of sarcoidosis. We reviewed the studies focussing on T-cell and B-cell responses to tubercular antigens in patients with sarcoidosis. Pooled data from various studies does provide a suggestive, though not unequivocal evidence in favour of mycobacteria as a cause of sarcoidosis. These findings not only reinforce the possible pathogenic role of mycobacterial antigens in sarcoidosis, but at the same time also limit the clinical utility of molecular and serological studies based on mycobacterial antigens in the differential diagnosis of TB from sarcoidosis, particularly in a country with high endemicity for TB.     

Molecular evidence for the role of mycobacteria in sarcoidosis: a meta-analysis.

The aetiology of sarcoidosis is currently unknown. Due to the clinical and histological similarities between sarcoidosis and tuberculosis, the role of mycobacteria has been repeatedly investigated as an aetiological agent for sarcoidosis. The current meta-analysis aimed to evaluate the available molecular evidence on the possible role of mycobacteria in the development of sarcoidosis. The MEDLINE, EMBASE, CINAHL, DARE and CENTRAL databases were searched for relevant studies published from 1980 to 2006, and studies evaluating the presence of mycobacteria using molecular techniques in biological samples of patients with sarcoidosis were included in the current analysis. The 95% confidence intervals (CI) were calculated for the expected proportion (of individual studies); the data was then pooled to obtain a summary success rate with 95% CI. The odds ratio (95% CI) was also calculated in order to assess the presence of mycobacteria in samples of patients with sarcoidosis versus those from nonsarcoidosis control samples. The database search yielded 31 studies. All studies used polymerase chain reaction for nucleic acid amplification followed by identification of nucleic acid sequences specific for different types of mycobacteria. Overall, 231 out of the 874 patients were positive for mycobacteria with a positive signal rate of 26.4 (23.6-29.5%), and the odds of finding mycobacteria in samples of patients with sarcoidosis versus controls were 9.67 (4.56-20.5%) using the random effects model and 19.49 (11.21-35.54%) using the exact method. There was methodological and statistical heterogeneity and evidence of publication bias. The results of the current study illustrate a demonstrable mycobacterial presence in sarcoidosis lesions suggesting an association between mycobacteria and some cases of sarcoidosis. To avoid methodological diversity, larger multicentre trials with a central laboratory for sample testing should be designed.