Diagnosis of extrapulmonary tuberculosis by PCR

Osteoarticular tuberculosis in an HIV-positive patient: a case report

The authors report a case of a 38-year-old HIV-positive woman, with subcutaneous nodules on the thoracic region with 3 months of evolution. Clinical, laboratory, and epidemiological features were evaluated and associated with apparent damage to the T11-T12 vertebrae, identification by imaging tests, positivity in a polymerase chain reaction-based test, and reactivity to the Mantoux tuberculin skin test (PPD-RT 23). The patient was diagnosed with osteoarticular tuberculosis and received treatment for a year, and clinical cure was achieved.

Tuberculous mastitis presenting as a lump: a mimicking disease in a pregnant woman case report and review of literature

Tuberculosis (TB) of the breast is a rare entity, and can be confused with many other breast disorders, like mamma carcinoma or inflammatory breast cancer. When finding granulomatous mastitis (GM) on histology, it is important to make a differential diagnosis and seek actively for clues on the presence of tuberculosis, sarcoidosis, Wegener's granulomatosis, or idiopathic granulomatous mastitis, since treatment strategies differ and maltreatment has major implications on morbidity and mortality. An extensive clinical evaluation, laboratory work up, and imaging will lead in most cases to the right diagnosis. Anti-tuberculous therapy is the core treatment for breast TB, and surgery is indicated for extensive or persistent residual disease. Here we present a case of tuberculous mastitis and a review of literature on GM.

Use of conventional PCR and smear microscopy to diagnose pulmonary tuberculosis in the Amazonian rainforest area

The diagnostic usefulness of Ziehl-Neelsen (ZN)-stained sputum smears combined with conventional polymerase chain reaction (ZN/PCR) to amplify IS6110 region DNA extracted from ZN slides was evaluated. The objective was to verify if this association could improve tuberculosis (TB) diagnosis in patients at remote sites. The study was carried out in 89 patients with culture-confirmed pulmonary TB as defined by the Brazilian Manual for TB Treatment. The participants were recruited in a reference unit for TB treatment in Rondônia, a state in the Amazonian area in northern Brazil. ZN, PCR, and culture performed in the sputum samples from these patients were analyzed in different combinations (i.e., ZN plus PCR and ZN plus culture). The prevalence rates of pulmonary TB in these patients were 32.6 and 28.1% considering culture and ZN/PCR, respectively. The sensitivity and specificity of ZN/PCR were 86 and 93%, respectively. ZN/PCR was able to detect more TB cases than ZN alone. This method could offer a new approach for accurate tuberculosis diagnosis, especially in remote regions of the world where culture is not available.

CFP10 and ESAT6 aptamers as effective Mycobacterial antigen diagnostic reagents

The development of effective Mycobacterial antigen diagnostic reagents remains a high priority. The 6-kDa early secreted antigenic target (ESAT6) and 10-kDa culture filtrate protein (CFP10) are secreted early by virulent Mycobacterium tuberculosis (M. tb) and are not present in the non-virulent Bacillus Calmette-Guerin (BCG). In this study, we used a Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technique to screen for a functional ssDNA aptamer "antibody" that specifically bound to ESAT6-CFP10 (CE) protein. The selected single ssDNA aptamers (CE24 and CE15) demonstrated the highest specificity and binding affinity to CFP10 (CE24: Kd = 3.75 × 10(-7) M) and ESAT6 (CE15: Kd = 1.6 × 10(-7) M). We further detected CFP10 and ESAT6 proteins in serum samples from active pulmonary tuberculosis (TB) patients, extrapulmonary TB patients and healthy donors by using an enzyme-linked oligonucleotide assay (ELONA). The results showed that the sensitivity and specificity were 100% and 94.1% (using CE24 aptamer-based ELONA) and 89.6% and 94.1% (using CE15 aptamer-based ELONA), respectively. A good correlation was observed between aptamer-based ELONA and T-SPOT TB assay. Thus, our study suggests that CE24 and CE15 have potentially broad applications as early antigen diagnostic agents not only for active pulmonary TB, extrapulmonary TB, but also possibly for latent TB infection and TB with immune-deficiency.

Microbial DNA testing for inflammatory diseases of the brain of uncertain etiology

Neurologists may be confronted with patients who present with inflammatory brain lesions where the diagnosis cannot be made through history and physical examination alone. Molecular testing for bacterial infections, tuberculosis, and fungal infections may aid in the diagnosis. Since the treatments for these disorders are different and delays can result in permanent neurologic disability and death, rapid and accurate diagnoses are critical. This review provides the neurologist with testing options and recommends ways to enhance sensitivity and specificity.

Factors influencing polymerase chain reaction outcomes in patients with clinically suspected ocular tuberculosis

Background

Polymerase chain reaction (PCR) assay can be a useful method for definitive diagnosis in paucibacillary infections such as ocular tuberculosis (TB). In this study, we have evaluated factors affecting PCR outcomes in patients with clinically suspected ocular TB. Patients with clinically suspected ocular TB were investigated by PCR of aqueous or vitreous samples. Three control groups were also tested: group 1 included culture-proven non-tuberculous endophthalmitis, group 2 culture-negative non-tuberculous endophthalmitis, and group 3 patients undergoing surgery for uncomplicated cataract. PCR targeted one or more of following targets: IS6110, MPB64, and protein b genes of Mycobacterium tuberculosis complex. Multiple regression analysis (5% level of significance) was done to evaluate the associations between positive PCR outcome and laterality of disease, tuberculin skin test (TST)/interferon-gamma release assay (IGRA), chest radiography, and type of sample (aqueous or vitreous). The main outcome measures were positive PCR by one or more gene targets, and factors influencing positive PCR outcomes.

Results

All 114 samples were tested for MPB64, 110 for protein b, and 88 for IS6110. MPB64 was positive in 70.2% (n = 80) of tested samples, protein b in 40.0% (n = 44), and IS6110 in only 9.1% (n = 8). DNA sequencing of amplicons from four randomly chosen PCR reactions showed homology for M. tuberculosis complex. Of the 80 PCR-positive patients, 71 completed a full course of antitubercular therapy, of which 65 patients (91.5%) had complete resolution of inflammation at final follow-up. Among controls, 12.5% (3 out of 24) in group 1 and 18.7% (6 out of 32) in group 2 also tested positive by PCR. No PCR-positive outcome was observed in control group 3 (n = 25). Multiple regression analysis revealed significant association of positive PCR outcome with bilateral presentation, but not with a positive TST/IGRA, chest radiography, or type of sample (aqueous/vitreous) used.

Conclusions

Careful selection of gene targets can yield high PCR positivity in clinically suspected ocular TB. Bilateral disease presentation but not any evidence of latent systemic TB influences PCR outcomes. False-positive results may be seen in ocular inflammation unrelated to ocular TB.

Identification of a 251 gene expression signature that can accurately detect M. tuberculosis in patients with and without HIV co-infection

Background

Co-infection with tuberculosis (TB) is the leading cause of death in HIV-infected individuals. However, diagnosis of TB, especially in the presence of an HIV co-infection, can be limiting due to the high inaccuracy associated with the use of conventional diagnostic methods. Here we report a gene signature that can identify a tuberculosis infection in patients co-infected with HIV as well as in the absence of HIV.

Methods

We analyzed global gene expression data from peripheral blood mononuclear cell (PBMC) samples of patients that were either mono-infected with HIV or co-infected with HIV/TB and used support vector machines to identify a gene signature that can distinguish between the two classes. We then validated our results using publically available gene expression data from patients mono-infected with TB.

Results

Our analysis successfully identified a 251-gene signature that accurately distinguishes patients co-infected with HIV/TB from those infected with HIV only, with an overall accuracy of 81.4% (sensitivity = 76.2%, specificity = 86.4%). Furthermore, we show that our 251-gene signature can also accurately distinguish patients with active TB in the absence of an HIV infection from both patients with a latent TB infection and healthy controls (88.9–94.7% accuracy; 69.2–90% sensitivity and 90.3–100% specificity). We also demonstrate that the expression levels of the 251-gene signature diminish as a correlate of the length of TB treatment.

Conclusions

A 251-gene signature is described to (a) detect TB in the presence or absence of an HIV co-infection, and (b) assess response to treatment following anti-TB therapy.

Detection of potential microbial antigens by immuno-PCR (PCR-amplified immunoassay)

Immuno-PCR (PCR-amplified immunoassay; I-PCR) is a novel ultrasensitive method combining the versatility of ELISA with the sensitivity of nucleic acid amplification of PCR. The enormous exponential amplification power of PCR in an I-PCR assay leads to at least a 10(2)-10(4)-fold increase in sensitivity compared with an analogous ELISA. I-PCR has been used to detect many biological molecules such as proto-oncogenes, toxins, cytokines, hormones, and biomarkers for autoimmune and Alzheimer's diseases, as well as microbial antigens and antibodies, and it can be adapted as a novel diagnostic tool for various infectious and non-infectious diseases. Quantitative real-time I-PCR has the potential to become the most analytically sensitive method for the detection of proteins. The sensitivity and specificity of a real-time I-PCR assay can be enhanced further with the use of magnetic beads and nanoparticles. This review is primarily focused on the detection of potential viral, bacterial and parasitic antigens by I-PCR assay, thus enabling their application for immunological research and for early diagnosis of infectious diseases.

Value of interferon-γ release assay and polymerase chain reaction for Mycobacterium tuberculosis in differentiation of intestinal tuberculosis from Crohn's disease

China is one of the countries having the highest burden of tuberculosis. The number of patients with Crohn's disease (CD) is gradually increasing in China. Sometimes intestinal tuberculosis (ITB) and CD are quite similar in clinical manifestations and the findings of radiological and endoscopic examinations, and it is difficult to differentiate the two diseases; however, the treatments and prognosis of the two diseases are completely different. Besides clinical characteristics, radiological examinations, endoscopic examinations, histopathological examinations, acid-fast staining, Mycobacterium tuberculosis culture, serum markers and tuberculin skin test (TST), interferon-γ release assay (IGRA) and polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR) have recently been used to differentiate ITD from CD. Both IGRA and TB-PCR have a high sensitivity and specificity in diagnosis of ITB when differentiating ITB from CD. This review focuses on the value of IGRA and TB-PCR in the differentiation of ITB from CD.

Posterior mediastinal tuberculous lymphadenitis with dysphagia as the main symptom: a case report and literature review

INTRODUCTION

Mediastinal tuberculous lymphadenitis (MTL) is mostly seen in primary tuberculosis in children, uncommon observed in adults. It usually presents the toxic symptoms of tuberculosis but rarely with symptoms characteristic of esophageal compression, such as dysphagia. Such patients can easily be misdiagnosed as esophageal neoplasm and get delayed or faulty treatment.

CASE REPORT

A 32-year-old man presented with dull chest pain of one month and dysphagia of five days. CRP was elevated, and a skin test was strongly positive. At upper endoscopy, a protruding lesion covered by normal mucosa was seen at 26 cm from the upper incisor. Barium swallow showed visible external compressive stricture on the middle-lower esophagus with normal mucosal pattern. Chest computed tomography (CT) scan showed a subcarinal mass adjacent to the esophageal wall in posterior mediastinum. An endoscopic ultrasonography (EUS) revealed a hypoechoic lesion suspected of esophageal stromal tumor in the fourth layer. A tissue was obtained by ultrasound-guided fine-needle aspiration (EUS-FNA), but cytopathology, bacilliculture and PCR test had no special findings. The patient required experimental antitubercular treatment and the protruding lesion shrank gradually during therapy period.

CONCLUSIONS

MTL could not be ignored in the differential diagnosis of posterior mediastinal mass with dysphagia. Analyzing and evaluating test results comprehensively is the key to make correct diagnosis and timely treatment. The experimental antituberculous treatment should be used if MTL is highly suspected.

Central Nervous System Tuberculosis: Challenges and Advances in Diagnosis and Treatment

Mycobacterium tuberculosis is one of the most prevalent human infections. Although the largest share of the burden of disease is in Africa and Asia, tuberculosis has a global footprint due to travel and migration. Resource constraints in many low- and middle-income countries are hampering efforts to control new infections and to prevent drug resistance. Infection of the central nervous system by Mycobacterium tuberculosis includes meningitis, tuberculoma, and abscess and carries a high morbidity and mortality. High clinical suspicion, combined with cerebrospinal fluid analysis and brain imaging studies, can improve the diagnostic certainty. The recent scale-up of nucleic acid amplification technology may allow earlier diagnosis of tuberculous meningitis in many regions of the world. Treatment of tuberculous infection of the central nervous system is usually empirical and follows conventional regimens for pulmonary tuberculosis. The optimal treatment regimen is still being elucidated and has been the subject of recent clinical trials.

Detection of Mycobacterium tuberculosis in blood by use of the Xpert MTB/RIF assay

We have developed a novel blood lysis-centrifugation approach for highly sensitive Mycobacterium tuberculosis detection in large volumes of blood with the Xpert MTB/RIF assay. One through 20 ml of blood was spiked with 0.25 to 10 CFU/ml of the M. tuberculosis surrogate M. bovis BCG. Multiple replicates of each sample were processed by a new lysis-centrifugation method and tested with the Xpert MTB/RIF assay. The assay was very sensitive with increased blood volumes. In the 20-ml samples, BCG was detected in blood spiked with 10, 5, 1, and 0.25 CFU/ml 100, 100, 83, and 57% of the time, respectively, compared to 100, 66, 18, and 18%, of the time, respectively, in 1-ml blood samples. Assay sensitivity was influenced by the type of anticoagulant used, with acid-citrate-dextrose solution B (ACD-B) providing the best results. A limit of detection of 10 CFU/ml was established with BCG spiked into ACD-B-treated blood, and 92, 36, and 33% of the samples with 5, 1, and 0.5 CFU/ml, respectively, were assay positive. The lysis buffer was stable both at room temperature and at 4°C for 2 months. The assay was tested with blood stored for 8 days without a change in sensitivity as measured by cycle threshold. This new assay format extends the capability of the Xpert MTB/RIF test, enabling up to 20 ml of blood to be tested rapidly for the presence of M. tuberculosis. This approach may be a useful method to detect extrapulmonary tuberculosis and the risk of death in immunocompromised patients.

Evaluation of interferon-γ release assay in the diagnosis of osteoarticular tuberculosis

The aim of this study was to assess the value of interferon-γ (IFN-γ) release assay (IGRA) (T-SPOT.TB) for patients with suspected osteoarticular tuberculosis (TB) in comparison with conventional and molecular methods. Of 145 patients with suspected osteoarticular TB, recruited from Beijing Chest Hospital between July 2011 and June 2012, 86 (59.3%)had osteoarticular TB (26 with culture-confirmed TB, 60 with probable TB), 24 (16.6%) were not having active TB. The remaining 17 (11.7%) inconclusive TB and 18 (12.4%) possible TB were excluded from final analysis. In addition to conventional tests and molecular method, T-SPOT.TB assay using peripheral blood mononuclear cells to examine IFN-γ response to early secretory antigenic target 6 and culture filtrate protein 10 was also performed. The sensitivity and specificity for T-SPOT.TB assay were 94.2% and 70.8%, respectively. A statistically significant difference in sensitivity was found between T-SPOT.TB assay (94.2%) and other tests (acid-fast bacilli smear (19.7%), culture (34.2%), real-time PCR (36.8%); P < 0.01, respectively). These results suggested that the IGRA assay could provide useful aids in the diagnosis of osteoarticular TB.