Target product profiles: leprosy diagnostics.

The World Health Organization (WHO) aims to reduce new leprosy cases by 70% by 2030, necessitating advancements in leprosy diagnostics. Here we discuss the development of two WHO's target product profiles for such diagnostics. These profiles define criteria for product use, design, performance, configuration and distribution, with a focus on accessibility and affordability. The first target product profile outlines requirements for tests to confirm diagnosis of leprosy in individuals with clinical signs and symptoms, to guide multidrug treatment initiation. The second target product profile outlines requirements for tests to detect Mycobacterium leprae or M. lepromatosis infection among asymptomatic contacts of leprosy patients, aiding prophylactic interventions and prevention. Statistical modelling was used to assess sensitivity and specificity requirements for these diagnostic tests. The paper highlights challenges in achieving high specificity, given the varying endemicity of M. leprae, and identifying target analytes with robust performance across leprosy phenotypes. We conclude that diagnostics with appropriate product design and performance characteristics are crucial for early detection and preventive intervention, advocating for the transition from leprosy management to prevention.

L'Organisation mondiale de la Santé (OMS) vise à réduire le nombre de nouveaux cas de lèpre de 70% d'ici 2030, ce qui nécessite un meilleur diagnostic de la maladie. Dans le présent document, nous évoquons le développement de deux profils de produit cible établis par l'OMS à cette fin. Ces profils définissent des critères en matière d'utilisation, de conception, de performances, de configuration et de distribution du produit, en accordant une attention particulière à l'accessibilité et à l'abordabilité. Le premier profil de produit cible décrit les exigences pour les tests servant à confirmer le diagnostic de la lèpre chez les individus qui présentent des signes cliniques et des symptômes, afin d'orienter l'instauration d'un traitement à base de plusieurs médicaments. Le second profil de produit cible décrit les exigences pour les tests servant à détecter une infection à Mycobacterium leprae ou M. lepromatosis parmi les contacts asymptomatiques de patients lépreux, ce qui contribue à l'adoption de mesures prophylactiques et à la prévention. Nous avons eu recours à une modélisation statistique pour évaluer les exigences de sensibilité et de spécificité de ces tests diagnostiques. Cet article met en évidence les obstacles à l'atteinte d'un niveau élevé de spécificité en raison de l'endémicité variable de M. leprae, et à l'identification d'analytes cibles offrant de bons résultats chez les phénotypes lépreux. Nous concluons qu'un diagnostic reposant sur des caractéristiques de performance et de conception appropriées est essentiel pour détecter rapidement la maladie et intervenir en amont, et nous plaidons pour une prévention plutôt qu'une gestion de la lèpre.

La Organización Mundial de la Salud (OMS) pretende reducir los nuevos casos de lepra en un 70% para 2030, lo que requiere avances en el diagnóstico de la lepra. Aquí se analiza el desarrollo de dos perfiles de productos objetivo de la OMS para este tipo de diagnósticos. Estos perfiles definen los criterios de uso, diseño, rendimiento, configuración y distribución de los productos, centrándose en su accesibilidad y asequibilidad. El primer perfil de producto objetivo describe los requisitos de las pruebas para confirmar el diagnóstico de la lepra en personas con signos y síntomas clínicos, con el fin de orientar el inicio del tratamiento con múltiples fármacos. El segundo perfil de producto objetivo describe los requisitos de las pruebas para detectar la infección por Mycobacterium leprae o M. lepromatosis entre los contactos asintomáticos de los pacientes con lepra, para facilitar las intervenciones profilácticas y la prevención. Se utilizaron modelos estadísticos para evaluar los requisitos de sensibilidad y especificidad de estas pruebas diagnósticas. El artículo destaca las dificultades para lograr una alta especificidad, dada la diferente endemicidad de M. leprae, y para identificar analitos diana con un rendimiento sólido en todos los fenotipos de lepra. Concluimos que los diagnósticos con un diseño de producto y unas características de rendimiento adecuados son fundamentales para la detección precoz y la intervención preventiva, lo que favorece la transición del manejo de la lepra a la prevención.

Highly sensitive and rapid determination of Mycobacterium leprae based on real-time multiple cross displacement amplification.

BACKGROUND: Mycobacterium leprae (ML) is the pathogen that causes leprosy, which has a long history and still exists today. ML is an intracellular mycobacterium that dominantly induces leprosy by causing permanent damage to the skin, nerves, limbs and eyes as well as deformities and disabilities. Moreover, ML grows slowly and is nonculturable in vitro. Given the prevalence of leprosy, a highly sensitive and rapid method for the early diagnosis of leprosy is urgently needed. RESULTS: In this study, we devised a novel tool for the diagnosis of leprosy by combining restriction endonuclease, real-time fluorescence analysis and multiple cross displacement amplification (E-RT-MCDA). To establish the system, primers for the target gene RLEP were designed, and the optimal conditions for E-RT-MCDA at 67 °C for 36 min were determined. Genomic DNA from ML, various pathogens and clinical samples was used to evaluate and optimize the E-RT-MCDA assay. The limit of detection (LoD) was 48.6 fg per vessel for pure ML genomic DNA, and the specificity of detection was as high as 100%. In addition, the detection process could be completed in 36 min by using a real-time monitor. CONCLUSION: The E-RT-MCDA method devised in the current study is a reliable, sensitive and rapid technique for leprosy diagnosis and could be used as a potential tool in clinical settings.

Transcription Factor HES-1: How Is the Expression of This Transcriptional Factor in Paucibacillary Leprosy Patients?

INTRODUCTION: Leprosy is an ancient and chronic infectious disease caused by 2 mycobacteria (Mycobacterium leprae and Mycobacterium lepromatosis). Recently, our research group observed that HES-1, an innate cellular component of the Notch signaling pathway, is related to the pathogenesis of leprosy. Therefore, it could be helpful in its detection. OBJECTIVE: To determine the expression of HES-1 in the skin of patients with paucibacillary (PB) leprosy. METHODS: A cross-sectional, descriptive, observational study was conducted. Forty-five skin samples from patients with leprosy were evaluated (30 samples from MB leprosy and 15 from PB leprosy) using immunohistochemistry of HES-1 and S-100. RESULTS: PB leprosy biopsies revealed a reduction of HES-1 in 66.7% of the epidermis, 80% of the eccrine glands, and 62.5% of the hair follicles of these patients, with statistical differences in the control group (P < 0.0001). Besides, HES-1 showed similar utility to S-100 immunostaining in detecting the MB and PB leprosy. CONCLUSIONS: HES-1 is a transcriptional factor also reduced in PB patients' epidermis and skin appendages. Finally, our data show that HES-1 could be a biomarker in diagnosing PB and MB leprosy.

Sensitivity of different DNA extraction methods and PCR to detect resistance in patients with leprosy stratified by the bacilloscopic index.

INTRODUCTION: Antimicrobial resistance in leprosy is an emerging problem, and the quantitative impact of low bacilloscopic indexes (BIs) on the sensitivity of molecular tests is unknown. We aimed to evaluate the sensitivity of gene sequencing for the detection of mutations related to antimicrobial resistance in Mycobacterium leprae in patients with low BIs using an analytical model. METHODS: Patients with leprosy were included and divided into two groups depending on their BIs (≥ 2+ and < 2+). The sensitivities of the two DNA extraction methods were compared after amplifying and sequencing the repetitive element (RLEP), folP1, rpoB and gyrA in M. leprae. RESULTS: We included 56 patients with leprosy: 35 had BIs less than 2+ (22 had negative slit-skin smear [SSS] results) and 21 patients had BIs greater than or equal to 2+. The sensitivity of the amplification of the RLEP target and the gene sequencing of folP1, rpoB and gyrA was 50 to 70% lower in patients with a BI less than 2+ and was significantly reduced in patients with lower BIs for all targets (p < 0.001). One patient had a mutation in the folP1 gene, and 14 patients had mutations in the gyrA gene, but no mutations related to antimicrobial resistance were found. CONCLUSIONS: We can conclude that the sensitivity of molecular tests is directly related to the BI, but these tests can still detect up to 20% of the targets in patients with BIs < 2+. New strategies to improve the sensitivity for detecting antimicrobial resistance in leprosy patients and reasonable clinical criteria for follow-up and the introduction of alternative treatments must be developed.

Laboratory perspectives for Leprosy: Diagnostic, prognostic and predictive tools.

The diagnosis of leprosy poses several challenges. The bacillary load, serology, and tissue response are determined by the host immune status, which make individual tests unsuitable across the spectrum. The sensitivity of tests for identifying paucibacillary cases remains limited, on the other hand, many tests lack specificity in differentiating contacts from diseased cases. Nonetheless, a plethora of laboratory tests have been added to the armamentarium of the clinicians dealing with leprosy. In the current review, we critically analyze the tests available for diagnosis, prognostication, and prediction of treatment response in leprosy. We discuss in brief the conventional tests available and detail the newer serologic and molecular tests added over the past few years with an attempt to suggest the pros and cons of each, and the tests best fit for each clinical scenario. Slit skin smears and skin or nerve biopsies are primarily performed to exclude clinical mimics, confirm a diagnosis, and immunologically subtype the case. Antibody titres of phenolic glycolipid-1 and its synthetic variants can be measured in serum and saliva and provide noninvasive means to detect leprosy with good specificity. Conventional, quantitative, real-time, and other variants of PCR can detect M. leprae DNA and have been used to effect in blood, tissue, and urine samples. T helper I and II cytokine signatures can be used to differentiate the subtypes of leprosy. Newer machine learning algorithms use combinations of these tests to predict the development of leprosy in contacts. Tests to detect treatment response, antimicrobial drug resistance, and predict the onset of reactions in leprosy can be used to advantage. We compare the characteristics of these tests and suggest an algorithm for leprosy diagnosis optimally utilizing them in various clinical settings.

Accuracy of rapid point-of-care serological tests for leprosy diagnosis: a systematic review and meta-analysis.

BACKGROUND: Leprosy is a chronic infectious disease, still endemic in many countries that may lead to neurological, ophthalmic, and motor sequelae if not treated early. Access to timely diagnosis and multidrug therapy (MDT) remains a crucial element in the World Health Organization's strategy to eliminate the disease as a public health problem. OBJECTIVES: This systematic review aims to evaluate the accuracy of rapid point-of-care (POC) tests for diagnosis of leprosy. METHODS: Searches were carried out in electronic databases (PubMed, EMBASE, CRD, Cochrane Library and LILACS) in April 2021 for patients with suspicion or confirmatory diagnostic of leprosy, classified in multibacillary (MB) or paucibacillary (PB) cases, performing rapid POC serological tests compared to clinical evaluation, smear microscopy and immunohistochemistry analysis. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2). A meta-analysis was undertaken to generate pooled estimates of diagnostic parameters, presenting sensitivity, specificity and diagnostic odds ratio (DOR) values. The review protocol was registered at PROSPERO, CRD # 42014009658. FINDINGS: From 893 potentially relevant references, 12 articles were included reporting 16 diagnostic tests accuracy studies with 5395 individuals enrolled. Meta-analysis of NDO-LID and PGL-I tests data in MB patients showed sensitivity and specificity [95% confidence interval (CI)] of 0.83 (0.71-0.91), 0.91 (0.72-0.97); and 0.92 (0.86-0.96), 0.93 (0.78-0.98); respectively, with high heterogeneity among the studies. MAIN CONCLUSIONS: Our results can inform policymakers regarding the possibility of implementing accurate, rapid POC tests for leprosy in public health services, especially within primary health care.

Development and validation of a multiplex real-time qPCR assay using GMP-grade reagents for leprosy diagnosis.

Leprosy is a chronic dermato-neurological disease caused by Mycobacterium leprae, an obligate intracellular bacterium. Timely detection is a challenge in leprosy diagnosis, relying on clinical examination and trained health professionals. Furthermore, adequate care and transmission control depend on early and reliable pathogen detection. Here, we describe a qPCR test for routine diagnosis of leprosy-suspected patients. The reaction simultaneously amplifies two specific Mycobacterium leprae targets (16S rRNA and RLEP), and the human 18S rRNA gene as internal control. The limit of detection was estimated to be 2.29 copies of the M. leprae genome. Analytical specificity was evaluated using a panel of 20 other skin pathogenic microorganisms and Mycobacteria, showing no cross-reactivity. Intra- and inter-operator Cp variation was evaluated using dilution curves of M. leprae DNA or a synthetic gene, and no significant difference was observed between three operators in two different laboratories. The multiplex assay was evaluated using 97 patient samples with clinical and histopathological leprosy confirmation, displaying high diagnostic sensitivity (91%) and specificity (100%). Validation tests in an independent panel of 50 samples confirmed sensitivity and specificity of 97% and 98%, respectively. Importantly, assay performance remained stable for at least five months. Our results show that the newly developed multiplex qPCR effectively and specifically detects M. leprae DNA in skin samples, contributing to an efficient diagnosis that expedites the appropriate treatment.

A pilot study to determine Neisseria gonorrhoeae-Chlamydia trachomatis coinfection rates in symptomatic patients attending STI Clinics, New Delhi, India.

BACKGROUND: Neisseria gonorrhoeae and Chlamydia trachomatis are the two most prevalent bacterial sexually transmitted infections. For over two decades, treatment guidelines have recommended empirical co-treatment for N.gonorrhoeae and C.trachomatis as symptoms overlap and co-infection is common. Studies from India estimating the same are limited and mostly based on conventional techniques. AIM AND OBJECTIVE: The aim of this study was to determine the frequency of N.gonorrhoeae and C.trachomatis coinfection using nucleic acid amplification tests. Further, we assessed the utility of pus cell estimation in Gram stained smears as a screening tool for inclusion of samples for molecular diagnosis. METHODS: This was a prospective study conducted at two tertiary care hospitals; 100 patients (55 females and 45 males) with genitourinary discharge attending STI clinics were recruited, and endocervical or urethral swabs were collected. PCRs for N.gonorrhoeae and C.trachomatis were put up. In addition, microscopy and culture for gonococcus was performed followed by antimicrobial susceptibility testing. Statistical analysis was performed using the SPSS 16 software. RESULTS: N.gonorrhoeae infection was more common than C.trachomatis. A total of 14 patients were positive by PCR (9 males and 5 females) for gonococcus. However, culture was positive only in 8 male patients. PCR for C.trachomatis was positive in 9 (4 males and 5 females) and the co-infection rate was 5%. The sensitivity and negative predictive value of pus cell estimation was 100% for males and 64% and 94.6% respectively for females. All isolates were susceptible to extended spectrum cephalosporins and azithromycin. LIMITATION: The sample size of the study was small. CONCLUSION: Frequency of N.gonorrhoeae/C.trachomatis coinfection in symptomatic STI patients is low. Coinfection is considerably overestimated and necessary confirmation of etiological diagnosis could reduce widespread empirical administration of broad-spectrum antibiotics.

RLEP LAMP for the laboratory confirmation of leprosy: towards a point-of-care test.

BACKGROUND: Nucleic acid-based amplification tests (NAAT), above all (q)PCR, have been applied for the detection of Mycobacterium leprae in leprosy cases and household contacts with subclinical infection. However, their application in the field poses a range of technical challenges. Loop-mediated isothermal amplification (LAMP), as a promising point-of-care NAAT does not require sophisticated laboratory equipment, is easy to perform, and is applicable for decentralized diagnosis at the primary health care level. Among a range of gene targets, the M. leprae specific repetitive element RLEP is regarded as highly sensitive and specific for diagnostic applications.  METHODS: Our group developed and validated a dry-reagent-based (DRB) RLEP LAMP, provided product specifications for customization of a ready-to-use kit (intended for commercial production) and compared it against the in-house prototype. The assays were optimized for application on a Genie® III portable fluorometer. For technical validation, 40 "must not detect RLEP" samples derived from RLEP qPCR negative exposed and non-exposed individuals, as well as from patients with other conditions and a set of closely related mycobacterial cultures, were tested together with 25 "must detect RLEP" samples derived from qPCR confirmed leprosy patients. For clinical validation, 150 RLEP qPCR tested samples were analyzed, consisting of the following categories: high-positive samples of multibacillary (MB) leprosy patients (> 10.000 bacilli/extract), medium-positive samples of MB leprosy patients (1.001-10.000 bacilli/extract), low-positive samples of MB leprosy patients (1-1.000 bacilli/extract), endemic controls and healthy non-exposed controls; each n = 30.  RESULTS: Technical validation: both LAMP formats had a limit of detection of 1.000 RLEP copies, i.e. 43-27 bacilli, a sensitivity of 92% (in-house protocol)/100% (ready-to-use protocol) and a specificity of 100%. Reagents were stable for at least 1 year at 22 °C. Clinical validation: Both formats showed a negativity rate of 100% and a positivity rate of 100% for high-positive samples and 93-100% for medium positive samples, together with a positive predictive value of 100% and semi-quantitative results. The positivity rate for low-positive samples was 77% (in-house protocol)/43% (ready-to-use protocol) and differed significantly between both formats.  CONCLUSIONS: The ready-to-use RLEP DRB LAMP assay constitutes an ASSURED test ready for field-based evaluation trials aiming for routine diagnosis of leprosy at the primary health care level.

Neutrophil-to-lymphocyte Ratio: A Biomarker for Predicting Systemic Involvement in Henoch-Schonlein Purpura.

BACKGROUND: Henoch-Schonlein purpura (HSP) is one of the commonest entities included within the category of cutaneous vasculitis (CV). Our work is purposed to explore the predictive value of neutrophil-to-lymphocyte ratio (NLR) for systemic involvement in Henoch- Schonlein purpura patients. This ratio is known as an inflammatory marker, and is used to assess the systemic inflammation associated with various diseases. Our objective is to establish whether it can be applied for the prediction of renal and gastrointestinal (GI) or purely renal involvement in Henoch-Schonlein purpura. AIM: To determine the relationship between neutrophil-to-lymphocyte ratio and systemic involvement in Henoch-Schonlein purpura Methods: This is a retrospective review of the patients who were diagnosed with Henoch-Schonlein purpura in our hospital between 2012 and 2018. RESULTS: A total of 57 patients met our inclusion criteria. Pre-treatment neutrophil-to-lymphocyte ratio was significantly associated with renal and/or GI manifestations of the disease (p<0.001). The optimal cut-off value of this ratio for predicting systemic involvement was 2.48, with a 95% specificity and a 94% sensitivity. In addition, pretreatment ratio was also found to be significantly correlated with the severity of relevant systemic manifestations of Henoch-Schonlein purpura (r=0.831; p<0.01). LIMITATIONS: The small number of patients recruited for our research, its retrospective design, and the inclusion of patients attending the same hospital. CONCLUSION: This study suggests that neutrophil-to-lymphocyte ratio is suitable as a potential indicator for predicting the systemic involvement in Henoch-Schonlein purpura.

Rapid diagnosis of Leishmania infection with a portable loopmediated isothermal amplification device.

L. donovani is an intracellular protozoan parasite, that causes visceral leishmaniasis (VL), and consequently, post-kala azar dermal leishmaniasis (PKDL). Diagnosis and treatment of leishmaniasis is crucial for decreasing its transmission. Various diagnostic techniques like microscopy, enzyme-linked immunosorbent assays (ELISA) and PCR-based methods are used to detect leishmaniasis infection. More recently, loop-mediated isothermal amplification (LAMP) assay has emerged as an ideal diagnostic measure for leishmaniasis, primarily due to its accuracy, speed and simplicity. However, point-of-care diagnosis is still not been tested with the LAMP assay. We have developed a portable LAMP device for the monitoring of Leishmania infection. The LAMP assay performed using our device can detect and amplify as little as 100 femtograms of L. donovani DNA. In a preliminary study, we have shown that the device can also amplify L. donovani DNA present in VL and PKDL patient samples with high sensitivity (100%), specificity (98%) and accuracy (99%), and can be used both for diagnostic and prognostic analysis. To our knowledge, this is the first report to describe the development and application of a portable LAMP device which has the potential to evolve as a point-of-care diagnostic and prognostic tool for Leishmania infections in future.

Potential of recombinant LiHyQ, a novel Leishmania infantum protein, for the diagnosis of canine visceral leishmaniasis and as a diagnostic and prognostic marker for human leishmaniasis and human immunodeficiency virus co-infection: A preliminary study.

Laboratory diagnosis of leishmaniasis shows variable efficacy in detecting infected mammalian hosts and there is a need to identify suitable antigens to improve the accuracy of diagnostic tests. In the present study, a L. infantum hypothetical protein called LiHyQ was evaluated for the diagnosis of tegumentary (TL) and visceral (VL) leishmaniasis using canine and human samples. A collection of dog sera (n=155) were tested and contained samples from asymptomatic (n=20) and symptomatic (n=25) VL animals, from healthy dogs living in endemic (n=25) or non-endemic (n=25) areas of disease, from Leish-Tec® vaccinated dogs (n=20) or from dogs infected with Ehrlichia canis (n=15), Babesia canis (n=10) and Trypanosoma cruzi (n=15). Sensitivity (Se), Specificity (Sp), Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of 100% were observed for rLiHyQ with these samples, whereas the Se, Sp, PPV and NPV values with L. infantum Soluble Leishmania Antigen (SLA) preparation were 60.0%, 99.0%, 96.0% and 86.0%, respectively. A collection of human sera (n=305) were tested and contained samples from TL (n=50) and VL (n=40) patients, from VL/HIV co-infected patients (n=35), from patients infected with HIV alone (n=30), Chagas Disease (n=30), malaria (n=10), tuberculosis (n=10), paracoccidioidomycosis (n=15), leprosy (n=30) or aspergillosis (n=15); and from healthy subjects (n=40). Se, Sp, PPV and NPV values of 100% were observed for rLiHyQ with these samples, whereas the Se, Sp, PPV and NPV values with SLA were 58.0%, 76.0%, 50.0% and 82.0%, respectively. The antibody reactivity against the protein was compared with commercial kits, and the kappa index varied from 0.95 to 1.00 for rLiHyQ, and of 0.55 to 0.82 for the kits. In addition, the serological follow-up of treated patients showed a significant reduction in rLiHyQ-specific IgG antibody levels. All canine and human samples were tested at the same time using the same reagents, in order to reduce experimental variation and interference in data interpretation. In conclusion, our preliminary data suggest a diagnostic and prognostic role for rLiHyQ against leishmaniasis.

Development of a novel loop-mediated isothermal amplification assay for rapid detection of Mycobacterium leprae in clinical samples.

BACKGROUND: Sensitive and definitive diagnostic tests are required for timely treatment of leprosy and to control its transmission. AIM: In the present study, we report the development of loop-mediated isothermal amplification assay using six primers targeting the RLEP gene sequence uniquely present in Mycobacterium leprae. METHODS: Tissue punch samples (n = 50) and slit aspirates (n = 50) from confirmed cases of leprosy (M. leprae positive by quantitative polymerase chain reaction), reporting at the Department of Dermatology, Safdarjung Hospital, New Delhi, were analyzed using newly developed closed tube loop-mediated isothermal amplification assay. The sensitivity and specificity; positive predictive value, negative predictive value and accuracy were calculated using MedCalc statistical software. RESULTS: The loop-mediated isothermal amplification assay specifically amplified M. leprae genomic DNA with an analytical sensitivity of 100 fg. About 47 Out of the 50 quantitative polymerase chain reactions confirmed M. leprae positive tissue samples, 47 were positive by loop-mediated isothermal amplification assay (sensitivity 94%; 95% confidence interval 83.5%-98.8%) while only 31/50 were positive by histopathology (sensitivity 62%; 95% confidence interval 47.2%-75.4%) . Using slit aspirate samples of these 50 patients, 42 were positive by both quantitative polymerase chain reaction and loop-mediated isothermal amplification assay (sensitivity 84%; 95% confidence interval 70.9%-92.8%) while only 23/50 (sensitivity 46%; 95% confidence interval 31.8%-60.7%) were positive by microscopy. LIMITATIONS: In the present study, the leprosy patient cohort was not uniform, as it comprised a lower number of paucibacillary cases (22%) compared to multibacillary (78%) cases. CONCLUSION: Loop-mediated isothermal amplification assay established here provides a rapid and accurate diagnostic test for leprosy in terms of sensitivity and specificity. The assay is simple to perform in comparison with other molecular techniques (polymerase chain reaction/quantitative polymerase chain reaction) and has potential for field applicability.

Development of a Loop-mediated isothermal amplification (LAMP) technique for specific and early detection of Mycobacterium leprae in clinical samples.

Leprosy, a progressive, mutilating and highly stigmatized disease caused by Mycobacterium leprae (ML), continues to prevail in the developing world. This is due to the absence of rapid, specific and sensitive diagnostic tools for its early detection since the disease gets notified only with the advent of physical scarring in patients. This study reports the development of a Loop-mediated isothermal amplification (LAMP) technique for fast, sensitive and specific amplification of 16S rRNA gene of ML DNA for early detection of leprosy in resource-limited areas. Various parameters were optimized to obtain robust and reliable amplification of ML DNA. Blind clinical validation studies were performed which showed that this technique had complete concurrence with conventional techniques. Total absence of amplification of negative control DNA confirmed the specificity of this test. Various visual detection methods viz. colorimetric, turbidity differentiation and bridge flocculation were standardized to establish easy-to-read and rapid diagnosis. This technique eliminates the lack of accuracy and sensitivity in skin smear tests in patients and the requirement for expensive lab equipments and trained technicians. The technique holds promise for further expansion and has the potential to cater to the unmet needs of society for a cheap, highly-sensitive and robust rapid diagnosis of ML.

Sensitivity and specificity of multibacillary and paucibacillary leprosy laboratory tests: A systematic review and meta-analysis.

This systematic review (number register: CRD42018112736) was performed to compare the sensitivity and specificity of leprosy diagnostic methods. The search was conducted in 3 electronic databases in January 2021. Studies evaluating leprosy diagnostic tests were included according the eligibility criteria. Meta-analysis was performed to calculate the sensibility and specificity of the groups. We included 36 studies. The test sensitivity for paucibacillary patients was 0.31 (95%CI: 0.29-0.33) and the specificity was 0.92 (95%CI: 0.92-0.93). In multibacillary patients, the sensitivity was 0.78 (95%CI: 0.77-0.80) and specificity was 0.92 (95%CI: 0.92-0.93). Comparing the sensitivity and specificity of the different techniques included, it should be noted that polymerase chain reaction (PCR) test presented the highest sensitivity for paucibacillary patients, while the western blot technique showed the highest sensitivity for multibacillary patients. However, further studies are needed to optimise the diagnosis of leprosy, requiring research with a larger number of samples and more uniform protocols.

A systematic review and meta-analysis of studies on the diagnostic accuracy and screening of tests to detect antimicrobial resistance in leprosy.

Although multidrug therapy is considered an effective treatment for leprosy, antimicrobial resistance is a serious concern. We performed a systematic review of studies on the diagnostic accuracy and screening of tests for antimicrobial resistance in leprosy. This review was registered in PROSPERO (CRD42020177958). In April 2020, we searched for studies in the PubMed, EMBASE, Web of Science, Scopus, Scielo, and LILACS databases. A random effects regression model was used for the meta-analysis. We included 129 studies. Molecular tests for dapsone resistance had a sensitivity of 78.8% (95% confidence interval [CI] = 65.6-87.9) and a specificity of 97.0% (95% CI = 94.0-98.6). Molecular tests for rifampicin resistance had a sensitivity and specificity of 88.7% (95% CI = 80.0-93.9) and 97.3% (95% CI = 94.3-98.8), respectively. Molecular tests for ofloxacin resistance had a sensitivity and specificity of 80.9% (95% CI = 60.1-92.3) and 96.1% (95% CI = 90.2-98.5), respectively. In recent decades, no increase in the resistance proportion was detected. However, the growing number of resistant cases is still a clinical concern.

Oct-6 transcriptional factor a possible biomarker for leprosy diagnosis.

Leprosy is an infectious disease caused by Mycobacterium leprae that affects the skin and nerves. The nerve damage in leprosy may be related to alterations in transcriptional factors, such as Krox-20, Oct-6, Sox-10. Thirty skin biopsies in leprosy patients and 15 non-leprosy skin biopsies were evaluated using RT-qPCR to assess Krox-20, Oct-6, and Sox-10 and these data was related with S-100 immunohistochemistry. Changes in gene expression were observed in the skin and dermal nerves of leprosy patients in Oct-6 and Sox-10. When comparing Oct-6 with S-100 IHC as diagnostic tests for leprosy, Oct-6 showed a sensitivity of 73.3%, and specificity of 100%, while S-100 IHC showed a sensitivity of 96.6% and specificity of 100%. Our data suggest Oct-6 could be an auxiliary biomarker specific to detecting changes in dermal nerves in leprosy and thus useful to health workers and pathologists with no expertise to observe nerve injuries in leprosy.

A systematic review and meta-analysis of studies on the diagnostic accuracy and screening of tests to detect antimicrobial resistance in leprosy

Although multidrug therapy is considered an effective treatment for leprosy, antimicrobial resistance is a serious concern. We performed a systematic review of studies on the diagnostic accuracy and screening of tests for antimicrobial resistance in leprosy. This review was registered in PROSPERO (CRD42020177958). In April 2020, we searched for studies in the PubMed, EMBASE, Web of Science, Scopus, Scielo, and LILACS databases. A random effects regression model was used for the meta-analysis. We included 129 studies. Molecular tests for dapsone resistance had a sensitivity of 78.8% (95% confidence interval [CI] = 65.6−87.9) and a specificity of 97.0% (95% CI = 94.0−98.6). Molecular tests for rifampicin resistance had a sensitivity and specificity of 88.7% (95% CI = 80.0−93.9) and 97.3% (95% CI = 94.3−98.8), respectively. Molecular tests for ofloxacin resistance had a sensitivity and specificity of 80.9% (95% CI = 60.1−92.3) and 96.1% (95% CI = 90.2−98.5), respectively. In recent decades, no increase in the resistance proportion was detected. However, the growing number of resistant cases is still a clinical concern(AU).

Multicentric validation of indigenous molecular test Truenat™ MTB for detection of Mycobacterium tuberculosis in sputum samples from presumptive pulmonary tuberculosis patients in comparison with reference standards.

BACKGROUND & OBJECTIVES: : Early case detection is essential to interrupt transmission and to prevent further spread of tuberculosis (TB) in high endemic settings. Nucleic acid amplification tests (NAATs) with visual read-outs are ideal as point-of-care tests. Truenat™ MTB is an indigenous chip-based NAAT for detection of Mycobacterium tuberculosis, which involves extraction of DNA and real-time polymerase chain reaction (PCR) using portable, automated, battery-operated instruments. The current multicentric study was aimed to evaluate Truenat for detection of MTB in sputum samples obtained from patients with presumptive pulmonary TB with reference to culture as gold standard and Xpert as a comparator. METHODS: : The study was conducted at four sites, namely ICMR-National Institute for Research in Tuberculosis, Chennai; All India Institute of Medical Sciences, New Delhi; ICMR-National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra; and National Institute of TB and Respiratory Diseases, New Delhi. Patients suspected to have TB were screened for eligibility. Two sputum samples were collected from each patient. Tests included smear, Xpert and Truenat directly from the sputum sample and culture by Lowenstein-Jensen (L-J) medium and MGIT960 from decontaminated pellets. Sample used for Truenat assay was coded. Resolution of Truenat false positives was done using an in-house PCR with TRC4 primers. RESULTS: : The study enrolled 2419 presumptive TB patients after screening 2465 patients, and 3541 sputum samples were collected from the enrolled patients. Results of 2623 samples were available for analysis. Truenat showed a positivity rate of 48.5 per cent as compared to 37.0 per cent by Xpert. The sensitivities of Truenat and Xpert were was 88.3 and 79.7 per cent, respectively in comparison with culture. INTERPRETATION & CONCLUSIONS: : Truenat MTB identified more positives among culture-confirmed samples than Xpert and had higher sensitivity. In addition, other advantageous operational features of Truenat MTB were identified which would be useful in field settings.