Utility of Real-Time Quantitative Polymerase Chain Reaction in Detecting Mycobacterium tuberculosis

CRISPR/Cas12a-based assay for the rapid and high-sensitivity detection of Streptococcus agalactiae colonization in pregnant women with premature rupture of membrane

BACKGROUND

Streptococcus agalactiae or group B Streptococcus (GBS) is a leading infectious cause of neonatal morbidity and mortality. It is essential to establish a robust method for the rapid and ultra-sensitive detection of GBS in pregnant women with premature rupture of membrane (PROM).

METHODS

This study developed a CRISPR-GBS assay that combined the advantages of the recombinase polymerase amplification (RPA) and CRISPR/Cas12a system for GBS detection. The clinical performance of the CRISPR-GBS assay was assessed using vaginal or cervical swabs that were collected from 179 pregnant women with PROM, compared in parallel to culture-based matrix-assisted laser desorption ionization time-of-flight mass spectrometry (culture-MS) method and real-time quantitative polymerase chain reaction (qPCR) assay.

RESULTS

The CRISPR-GBS assay can be completed within 35 min and the limit of detection was as low as 5 copies μL^-1. Compared with the culture-MS, the CRISPR-GBS assay demonstrated a sensitivity of 96.64% (144/149, 95% confidence interval [CI] 92.39-98.56%) and a specificity of 100% (30/30, 95% CI  88.65-100%). It also had a high concordance rate of 98.88% with the qPCR assay.

CONCLUSIONS

The established CRISPR-GBS platform can detect GBS in a rapid, accurate, easy-to-operate, and cost-efficient manner. It offered a promising tool for the intrapartum screening of GBS colonization.

A case of postoperative tubercular spondylitis following microdiscectomy for lumbar disc herniation

Background:

Postoperative infections are one of the most common complications of spine surgery. However, following a lumbar microdiscectomy, a postoperative infection involving Mycobacterium tuberculosis (MTB) is extremely rare.

Case Description:

One and half months after a L4-5 microdiscectomy, a 47-year-old immunocompromised male with hepatitis B infection presented with low back and bilateral gluteal pain. The MRI revealed a large intraspinal/paraspinal fluid collection spanning from L4 to S1 along with an anterior epidural collection at L5. The patient underwent a L4 lumbar laminectomy for abscess drainage and wound debridement. After obtaining a positive culture for MTB, four antitubercular drug therapies (ATTs) were started, that is, isoniazid (H), rifampicin (R), ethambutol (E), a. One month later, the patient had minimal pain and no residual neurological deficit.

Conclusion:

MTB infection, although rare, should be considered among the differential diagnoses of postoperative infections following lumbar spine surgery in immunocompromised patients living in areas where tuberculosis is endemic.

Molecular detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary samples in a hospital-based study

OBJECTIVE

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a deadly infectious disease. India contributes to one-third of the global TB burden. However, no studies have been carried out in the Telangana (Hyderabad) population using real-time polymerase chain reaction (RT-PCR). Therefore, the current study evaluated the role of RT-PCR as a rapid and non-invasive test to diagnose TB by testing for pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB).

MATERIALS AND METHODS

This hospital-based study examined 1670 samples (900 EPTB; 770 PTB) comprising tissue (n = 537), peritoneal fluid (n = 420), sputum (n = 166), bronchial fluid (n = 126), cerebrospinal fluid (n = 145), ascetic fluid (n = 76), sputum pus (n = 78), urine (n = 79), and bronchoalveolar fluid (n = 43) samples. DNA from samples was separated using specific isolation kits and subjected to RT-PCR.

RESULTS

In this study, we enrolled 1670 subjects and categorized 54.4% as females and 45.6% as males. The collected samples were categorized as 48.5% of fluid samples, followed by tissue (32.2%), sputum (9.9%), urine (4.7%), and pus-swab (4.6%). RT-PCR analysis revealed that 4.7% patients were positive for Mtb. Our results revealed that 61% of the affected patients were male and 39% were female. Among the specimen types, tissue samples gave the highest proportion of positive results (36.3%).

CONCLUSION

The results showed that RT-PCR should be implemented and given top priority in TB diagnosis to save time and facilitate a definitive diagnosis. Tissue samples are highly recommended to screen the Mtb through the technique RTPCR. Future studies should extend the technique to the global population and exome sequencing analysis should be performed to identify TB risk markers.

Use of Digital Technology to Enhance Tuberculosis Control: Scoping Review

Background

Tuberculosis (TB) is the leading cause of death from a single infectious agent, with around 1.5 million deaths reported in 2018, and is a major contributor to suffering worldwide, with an estimated 10 million new cases every year. In the context of the World Health Organization’s End TB strategy and the quest for digital innovations, there is a need to understand what is happening around the world regarding research into the use of digital technology for better TB care and control.

Objective

The purpose of this scoping review was to summarize the state of research on the use of digital technology to enhance TB care and control. This study provides an overview of publications covering this subject and answers 3 main questions: (1) to what extent has the issue been addressed in the scientific literature between January 2016 and March 2019, (2) which countries have been investing in research in this field, and (3) what digital technologies were used?

Methods

A Web-based search was conducted on PubMed and Web of Science. Studies that describe the use of digital technology with specific reference to keywords such as TB, digital health, eHealth, and mHealth were included. Data from selected studies were synthesized into 4 functions using narrative and graphical methods. Such digital health interventions were categorized based on 2 classifications, one by function and the other by targeted user.

Results

A total of 145 relevant studies were identified out of the 1005 published between January 2016 and March 2019. Overall, 72.4% (105/145) of the research focused on patient care and 20.7% (30/145) on surveillance and monitoring. Other programmatic functions 4.8% (7/145) and electronic learning 2.1% (3/145) were less frequently studied. Most digital health technologies used for patient care included primarily diagnostic 59.4% (63/106) and treatment adherence tools 40.6% (43/106). On the basis of the second type of classification, 107 studies targeted health care providers (107/145, 73.8%), 20 studies targeted clients (20/145, 13.8%), 17 dealt with data services (17/145, 11.7%), and 1 study was on the health system or resource management. The first authors’ affiliations were mainly from 3 countries: the United States (30/145 studies, 20.7%), China (20/145 studies, 13.8%), and India (17/145 studies, 11.7%). The researchers from the United States conducted their research both domestically and abroad, whereas researchers from China and India conducted all studies domestically.

Conclusions

The majority of research conducted between January 2016 and March 2019 on digital interventions for TB focused on diagnostic tools and treatment adherence technologies, such as video-observed therapy and SMS. Only a few studies addressed interventions for data services and health system or resource management.

Accuracy of Commercial Molecular Diagnostics for the Detection of Pulmonary Tuberculosis in China: A Systematic Review

This systematic review assesses the accuracy of molecular diagnostic methods for the detection of pulmonary tuberculosis in studies performed in China, published in Chinese and English. We searched for studies that assessed the accuracy of molecular diagnostics for pulmonary TB in China in the China National Knowledge Infrastructure, the Wanfang Database, SinoMed, VIP Information, Pubmed, Embase, and the Cochrane Library. For each index test, a summary estimation for sensitivity and specificity was calculated using the bivariate random-effects model. A total of 59 studies were included in our analysis. Loop-mediated isothermal amplifcation (LAMP) assay (six studies; pooled sensitivity 90%, 95% CI 78-95%; specificity 93%, 85-97%), line probe assay (LPA) (one study; 87%, 84-90%; 94%, 92-95%) and polymerase chain reaction (PCR) (FQ-PCR and RT-PCR) (four studies; 90%, 55-99%; 93%, 71-99%) showed good diagnostic performance in the meta-analysis. The highest pooled sensitivity was from Xpert MTB/RIF (20 studies; pooled sensitivity 91%, 95% CI 87-94%). The highest pooled specificity was from cross-priming amplification (CPA) (six studies; pooled specificity 97%, 95-99%). The lowest pooled sensitivity and specificity were from simultaneous amplification and testing (SAT)-TB (three studies; 79%, 66-88%; 72%, 48-88%). In subgroup analysis, molecular diagnostics demonstrated higher sensitivity for pulmonary TB detection in smear-positive specimens. Xpert MTB/RIF, LAMP, LPA, CPA and PCR demonstrated high accuracy overall for pulmonary tuberculosis detection, while SAT-TB had poor performance.

Arthroscopic management for early-stage tuberculosis of the ankle

Background

Due to atypical clinical presentation, wide use of antibiotics, and lack of specificity in diagnosis, diagnosis of tubercular (TB) infection in joints is increasingly difficult, and misdiagnosis is common. The use of arthroscopy for the diagnosis and treatment of early-stage ankle TB has rarely been reported. This case series intended to present the clinical outcomes of arthroscopic management for early-stage ankle TB.

Methods

Fifteen patients with chronic synovitis of the ankle and suspicious cause of early-stage ankle TB underwent arthroscopic treatment from April 1, 2010, to March 31, 2016. These cases all failed to confirm diagnosis of TB by ankle arthrocentesis. They included seven males and eight females with an average age of 37.5 (8 to 70) in the study. Among them, five cases had history of pulmonary tuberculosis, and six had history of trauma. The procedure included synovial membrane biopsy and debridement. The diagnosis was confirmed by pathologic examination and culture. The treatment was combined with systemic anti-tuberculous drugs. Follow-up measurements included VAS score, AOFAS score, ESR, CRP, and MRI.

Results

After arthroscopic management, 13 cases confirmed TB by pathologic examination and culture, and two cases still remained clinically suspected TB; the rate of confirmed case was 87%. The incision healed well in all cases, and no serious complications were observed. There were significant differences in VAS scores, AOFAS scores, ESR, and CRP between before and after treatment (P < 0.01). Joint swelling disappeared or was relieved after 2 months in most patients. Ankle swelling and pain in one patient was improved after changing anti-tuberculous drugs. MRI suggested that all patients had effusion in the articular cavity, accompanied by bone edema of the distal tibia and talus before the treatment. After the surgery, the effusion was significantly reduced, and the signal of bone edema almost disappeared. No recurrent TB was found during the follow-ups.

Conclusion

Arthroscopic management for early-stage ankle TB is minimally invasive, safe, and reliable. It can easily obtain samples from specific area of TB for further confirmation of the diagnosis, while the debridement can also assist in local disease control. For cases of highly suspicious joint TB, arthroscopic biopsy and debridement after transient anti-TB treatment is recommended.

Level of evidence

Level IV, therapeutic case series

Electronic supplementary material

The online version of this article (10.1186/s13018-018-1048-y) contains supplementary material, which is available to authorized users.

The N-terminal domain of Mycobacterium tuberculosis PPE17 (Rv1168c) protein plays a dominant role in inducing antibody responses in active TB patients

The PPE (proline-proline-glutamic acid) proteins of Mycobacterium tuberculosis are characterized by a conserved N-terminal domain of approximately 180 amino acids and variable C-terminal domain. Since last decade, these proteins have gained much importance in the serodiagnosis of tuberculosis (TB) as they act as a source of antigenic variation. We have demonstrated earlier that one of the PPE proteins PPE17 (Rv1168c) induces strong B-cell and T-cell responses in active TB disease and also displays a higher antibody titer compared to immunodominant antigens such as ESAT-6, Hsp60 and PPD. However, the immunodominant domain of PPE17 (N-terminal or C-terminal) was not examined in detail. In the present study, we observed that antibody responses elicited in TB patients were directed mostly towards the N-terminal domain of PPE17 (N-PPE17). The antibody generated against N-PPE17 in TB patients did not significantly cross-react with N-terminal domains of other PPE proteins used in this study. Our data suggest that the N-terminal domain of PPE17 protein is immunodominant and could be used as a better serodiagnostic marker than the full-length PPE17 protein.