Line Probe Research Articles

Effects of boundary conditions on the transmitral pressure gradient for numerical simulation of flow in a left heart model

The transmitral pressure gradient is a crucial clinical indicator for diagnosing mitral regurgitation and stenosis. Numerical simulation of specific patients can obtain the complete pressure distribution in the left heart system, which is an important approach to evaluate cardiac function. However, the results are sensitive to the boundary conditions used in the numerical simulations. In the present work, we constructed a left heart model and assessed the effects of four typical boundary conditions on the transmitral pressure gradient, which is computed based on the Bernoulli equation and the line probe, respectively. The results show that the transmitral pressure gradient obtained by the line probe is sensitive to the boundary conditions. The sensitivity is closely related to the pressure in the atrium but has negligible effect on the pressure in the ventricle. This study sheds light on evaluating the pressure gradient of patient-specific treatments based on the numerical simulation of a left heart model.

Machine vision system for automatic defect detection of ultrasound probes

Industry 4.0 conceptualizes the automation of processes through the introduction of technologies such as artificial intelligence and advanced robotics, resulting in a significant production improvement. Detecting defects in the production process, predicting mechanical malfunctions in the assembly line, and identifying defects of the final product are just a few examples of applications of these technologies. In this context, this work focuses on the detection of ultrasound probes’ surface defects, with a focus on Esaote S.p.A.’s production line probes. To date, this control is performed manually and therefore biased by many factors such as surface morphology, color, size of the defect, and by lighting conditions (which can cause reflections preventing detection). To overcome these shortfalls, this work proposes a fully automatic machine vision system for surface acquisition of ultrasound probes coupled with an automated defect detection system that leverage artificial intelligence. The paper addresses two crucial steps: (i) the development of the acquisition system (i.e., selection of the acquisition device, analysis of the illumination system, and design of the camera handling system); (ii) the analysis of neural network models for defect detection and classification by comparing three possible solutions (i.e., MMSD-Net, ResNet, EfficientNet). The results suggest that the developed system has the potential to be used as a defect detection tool in the production line (full image acquisition cycle takes ~ 200 s), with the best detection accuracy obtained with the EfficientNet model being 98.63% and a classification accuracy of 81.90%.

Assessing boundary conditions in CFD for transvalvular pressure gradient calculation in cardiac hemodynamics

Abstract Background Computational fluid dynamics (CFD), which has the advantages of providing detailed pressure distribution, has been widely used for cardiac function assessment and heart disease diagnosis. However, the results are usually influenced by the boundary conditions. Particularly, the transvalvular pressure gradient, which serves as a crucial indicator for mitral stenosis and the efficacy of mitral valve surgery, can easily be miscalculated. Here, we assess the effects of widely used boundary conditions on the transvalvular pressure gradient computed based on the Bernoulli equation and the line probe, respectively. Purpose This study aims to determine the effects of boundary conditions on the transvalvular pressure gradient in CFD. Methods We constructed cardiac models including left atrium, left ventricle, aorta from CT and mitral valve from transesophageal echocardiography data (Figure 1). The intraventricular flow fields were computed using CFD tool with four different boundary conditions (BC) at the same cardiac output. BC1 involved specifying the total flow rate of the aorta, with zero pressure at the entrance of the pulmonary veins. BC2 maintained equal flow rates at the entrances of the pulmonary veins. BC3 followed Murray's law, where the flow rate ratio in the pulmonary veins is proportional to the 1.5 power of the area ratio. BC4 followed Poiseuille's law, where the flow rate ratio is proportional to the square of the area ratio. The results encompassed the mean transvalvular pressure gradient and peak transvalvular pressure gradient obtained through the Bernoulli equation and the line probe methods, respectively. Results Figures 2(A-D) present the contours of transvalvular pressure under peak flow velocity conditions and the isosurfaces of vorticity within the ventricle. The results show that the pressure within the atrium is notably lower in the BC2, leading to a 63% underestimation in the mean transvalvular pressure gradient and a 22.9% deviation in the peak transvalvular pressure gradient (Figure 2 F). The transvalvular pressure gradient for BC1, BC3, and BC4 do not exceed 10%. The results reveal that the pressure distribution and vorticity within the ventricle are consistent, primarily due to the influence of the mitral valve. Conclusion When evaluating transvalvular pressure gradient using CFD, it is crucial to specify appropriate boundary conditions. Using inappropriate boundary conditions may lead to underestimation of the transvalvular pressure gradient, thereby affecting further diagnostic decisions. In research studies, it is recommended to allocate flow in different branch vessels according to Murray's law, where the flow in different branch vessels is proportional to the 1.5 power of the vessel cross-sectional area.Modelling flow chartTransvalvular pressure gradient

Comparison of Molecular Testing Methods in Detecting Drug Resistance Tuberculosis

Tuberculosis (TB) is the leading cause of infectious disease-related deaths in Indonesia, and the COVID-19 pandemic has led to a decline in TB reporting and an increase in Drug-Resistant Tuberculosis (DR-TB). While traditional culture and Drug Susceptibility Testing (DST) takes 2-8 weeks, therefore, genotypic assays such as GeneXpert, Line Probe Assay (LPA), and sequencing offer faster and more precise diagnosis and drug resistance information.

Comparison of Truenat Mycobacterium tuberculosis with line probe assay for the diagnosis of rifampicin resistance and mutation pattern of Mycobacterium tuberculosis

Abstract Background: There is an increasing incidence of multidrug-resistant tuberculosis (TB)/preextensively drug-resistant TB (XDR TB) and XDR TB globally. Therefore, rapid diagnostic tests with good sensitivity and specificity are need of hour. Truenat Mycobacterium tuberculosis (MTB) is one such test which gives results in 1–2 h and can withstand a variety of environmental conditions. Objective: The objective of this study was to compare Truenat MTB with line probe assay (LPA) for the diagnosis of rifampicin resistance and to study the mutation pattern of MTB. Materials and Methods: A comparative record-based study was carried out among 325 patients with multidrug-resistant TB. Sputum samples for pulmonary TB and appropriate site samples for extrapulmonary TB were obtained and tested with Truenat-MTB and LPA. A comparison between results obtained by Truenat-MTB and LPA was done. Based on first-line-LPA and second-line-LPA, gene mutation pattern was studied. Results: Males (69.2%) were more than females (30.8%). 30–49 (34.5%) years of age were most commonly affected. The sensitivity, specificity, positive predictive value, and negative predictive value of Truenat MTB compared to LPA were 82.86%, 93.45%, 60.41%, and 97.83%, respectively. The most common gene mutation observed was katG MUT1 in 59 cases. This was followed by rpoB MUT1 in three cases, rpoB MUT2A in two cases, rpoB MUT2B in four cases, and rpoB MUT3 in 12 cases. gyrA mutation was seen in nine cases among which gyrA MUT3A was seen in one case, gyrA MUT3B in one case, and gyrA MUT3C was seen in four cases. Two cases of rrs MUT1 were seen. Five cases of inhA MUT1 were seen. Conclusion: Truenat has been found to be economical, less time-consuming, giving fast results, and accurate in the diagnosis of DR-TB. The most common gene mutation observed was katG MUT1 in 59 cases.

Molecular identification of Mycobacterium bovis in patients with tuberculosis attending a tertiary care hospital in South India

Background: Mycobacterium (M.) bovis is a member of Mycobacterium tuberculosis complex (MTBC). Clinical infection caused by M. bovis is indistinguishable from other MTBC and could pose a potential challenge for control of TB epidemic due to its zoonotic nature. Availability of reliable molecular diagnostic methods such as Genotype MTBC based on line probe assay (LPA) paves way for reliable differentiation of M. bovis from other MTBC. Objective: To determine the proportion of Mycobacterium bovis among the Mycobacterium tuberculosis complex isolates from patients with tuberculosis. Methods: In our study, we analysed MGIT positive cultures and performed Line probe assay (LPA) for identification of MTBC isolates. Total of 206 patient samples were taken, 104 pulmonary and 102 from extrapulmonary sites. Results: M.tuberculosis/ M.canettii was isolated in all pulmonary specimens (100%). Among 102 extrapulmonary samples, 99 % was identified as M.tuberculosis/ M.canettii, and 1 % as M. bovis BCG. Conclusion: Our study suggests that zoonotic TB by M. bovis may not be as prevalent in India and hence may not constitute a significant risk to public health in India. Keywords: TB; M. bovis; line probe assay.

Monolithic ceramic waveguide filter using a transition between GCPW feed and ceramic waveguide for 28 GHz

AbstractIn this letter, a mm‐wave monolithic ceramic waveguide filter using a transition between a grounded coplanar waveguide (GCPW) feed and a ceramic waveguide has been proposed. The published studies on monolithic ceramic waveguide filters with wideband properties for the mm‐wave are lacking. A desired external quality factor, satisfying wide bandwidth, is achieved using both inductive and capacitive couplings in the transition. The inductive coupling is realized with a waveguide's hole directly connected to the microstrip line probe of the GCPW. The capacitive coupling is employed with the slots of both GCPW and ceramic waveguide, which are placed facing each other. Adopting the presented transition, the inline monolithic ceramic waveguide filter for a fourth‐order Chebyshev response was designed. The fabricated filter provided the insertion and return losses of lower than 1.2 dB and higher than 10 dB, respectively, at frequencies from 26.43 to 29.76 GHz, with a fractional bandwidth of 11.85%.

Targeted deep sequencing of mycobacteria species from extrapulmonary sites not identified by routine line probe assays: A retrospective laboratory analysis of stored clinical cultures

ObjectivesNontuberculous mycobacteria (NTM) infections present a global health challenge. This study describes unidentified mycobacteria species from extrapulmonary sites, using advanced identification and sequencing techniques. MethodsExtrapulmonary mycobacteria growth indicator tube primary cultures collected retrospectively between 2019 and 2023, featuring unidentified mycobacteria species detected by GenoType Mycobacterium line probe assays, underwent multilocus targeted next-generation sequencing using Oxford Nanopore Technology, polymerase chain reaction amplicon Sanger sequencing, and Deeplex Myc-TB analysis. Previously collected clinical and laboratory data were reported. ResultsA total of 28 cultures, collected from extrapulmonary sites, each from different patients, were included. Mycobacterial mixtures were identified in 19 of 28 (68%) cultures, with four of 28 (14%) showing unidentified species based on sequencing of rpoB and hsp65 targets. Mycobacterium monacense was present in 13 of 28 (46%) of the cultures. Culturable Mycobacterium tuberculosis complex (MTBC) was identified in five extrapulmonary specimens that previously tested negative for MTBC using Xpert MTB/RIF Ultra. The comparative analysis between Sanger and targeted next-generation sequencing using Oxford Nanopore Technology sequencing (for hsp65) demonstrated 27 of 28 (96%) agreement on the predominant strain. Deeplex Myc-TB could not identify NTM-MTBC co-infections in minor subpopulations. ConclusionsThis study highlights the role of advanced sequencing in identifying NTM mixtures and mycobacterial co-infections. It calls for ongoing efforts to integrate next-generation sequencing into mycobacteria testing algorithms.

Concomitant Rifampicin-Sensitive Pulmonary Tuberculosis With Pre-extremely Drug-Resistant Neuro-Tuberculosis in Child With Steroid-Resistant Nephrotic Syndrome.

Mixed tuberculosis occurs with multiple clonally distinct mycobacterium tuberculosis strains in an individual. We present a 12-year-old girl with steroid-resistant nephrotic syndrome and drug-sensitive pulmonary tuberculosis (Xpert MTB/Rif) and preextensively drug-resistant tuberculosis neuro-tuberculosis (Line Probe Assay). Mixed tuberculosis involving drug-susceptible and drug-resistant strains can hinder treatment. This case highlights the challenges in diagnosing mixed tuberculosis to ensure effective management.

Evaluation of the GenoType NTM-DR line probe assay for nontuberculous mycobacteria using whole genome sequences as reference standard

Pulmonary nontuberculous mycobacteria (NTM) disease is an emerging public health challenge that is especially problematic in people with cystic fibrosis (CF). Effective treatment depends on accurate species and subspecies identification and antimicrobial susceptibility status. We evaluated the GenoType NTM-DR VER 1.0 assay using biobanked NTM isolates with whole genome sequence (WGS) data and control isolates (total n=285). Species and subspecies detection sensitivity and specificity were 100 % for all species and subspecies except for two subspecies of M. intracellulare, that demonstrated a small degree of discrepant identification between M. intracellulare subspecies intracellulare and subspecies chimaera. All antimicrobial resistance markers were identified with 100 % sensitivity and specificity.We conclude that the GenoType NTM-DR assay offers a rapid and accurate option for identifying the most frequently encountered pathogenic NTM taxa and drug resistance markers.SUPPORT: Colorado CF Research Development Program and Colorado CF National Resource Centers funded by the Cystic Fibrosis Foundation, NJH Advanced Diagnostics Laboratories, Colorado Advanced Industries Accelerator Grant

Utility of GeneXpert in Diagnosis of Pediatric Tuberculosis and Detection of Rifampicin Resistance

Abstract Background: Tuberculosis (TB) remains a significant public health challenge in developing countries, including India, where children under 15 years account for 12% of all TB cases. The National Tuberculosis Elimination Programme (NTEP) recommends the use of GeneXpert/Cartridge-Based Nucleic Acid Amplification Test (CBNAAT) for TB diagnosis, followed by Line Probe Assay (LPA) for detecting drug resistance. This study aimed to determine the prevalence of TB and rifampicin resistance in pediatric patients and to evaluate the utility of CBNAAT in comparison with LPA and Ziehl-Neelsen staining. Methods: This retrospective study was conducted over one year, from 1st January 2022 to 31st December 2022, at a tertiary care hospital in western Maharashtra. A total of 528 samples from pediatric patients (aged <18 years) suspected of having TB were included. Samples underwent CBNAAT testing and Ziehl-Neelsen staining. Positive samples were further analyzed using LPA or Mycobacterial Growth Indicator Tube (MGIT) culture. Results: Among the 528 samples analyzed, gastric lavage accounted for 81.25% of the specimens. CBNAAT detected TB in 61 (11.55%) of the samples, with 15 (24.59%) of these showing rifampicin resistance. Samples with very low or low bacterial loads were often missed by Ziehl-Neelsen staining. Conclusion: Pediatric tuberculosis continues to be a public health concern in developing countries. The study found an 11.55% positivity rate in children under 18 years of age, with 24.59% of positive cases exhibiting rifampicin resistance. The findings underscore the importance of using advanced diagnostic techniques like CBNAAT and highlight the limitations of Ziehl-Neelsen staining in detecting low bacterial loads.

Targeted next-generation sequencing of Mycobacterium tuberculosis from patient samples: lessons learned from high drug-resistant burden clinical settings in Bangladesh

ABSTRACT Lack of appropriate early diagnostic tools for drug-resistant tuberculosis (DR-TB) and their incomplete drug susceptibility testing (DST) profiling is concerning for TB disease control. Existing methods, such as phenotypic DST (pDST), are time-consuming, while Xpert MTB/RIF (Xpert) and line probe assay (LPA) are limited to detecting resistance to few drugs. Targeted next-generation sequencing (tNGS) has been recently approved by WHO as an alternative approach for rapid and comprehensive DST. We aimed to investigate the performance and feasibility of tNGS for detecting DR-TB directly from clinical samples in Bangladesh. pDST, LPA and tNGS were performed among 264 sputum samples, either rifampicin-resistant (RR) or rifampicin-sensitive (RS) TB cases confirmed by Xpert assay. Resistotypes of tNGS were compared with pDST, LPA and composite reference standard (CRS, resistant if either pDST or LPA showed a resistant result). tNGS results revealed higher sensitivities for rifampicin (RIF) (99.3%), isoniazid (INH) (96.3%), fluoroquinolones (FQs) (94.4%), and aminoglycosides (AMGs) (100%) but comparatively lower for ethambutol (76.6%), streptomycin (68.7%), ethionamide (56.0%) and pyrazinamide (50.7%) when compared with pDST. The sensitivities of tNGS for INH, RIF, FQs and AMGs were 93.0%, 96.6%, 90.9%, and 100%, respectively and the specificities ranged from 91.3 to 100% when compared with CRS. This proof of concept study, conducted in a high-burden setting demonstrated that tNGS is a valuable tool for identifying DR-TB directly from the clinical specimens. Its feasibility in our laboratory suggests potential implementation and moving tNGS from research settings into clinical settings.

Hepatitis C Virus Seroprevalence and Genotypic Distribution Among Hemodialysis Patients at a Teaching and Training Hospital in Western Rajasthan, India.

Background Hepatitis C virus (HCV) infection is a chronic hepatotropic blood-borne infection. The transmission of HCV in patients undergoing hemodialysis (HD) is more common in comparison to the general population due to factors such as frequent blood transfusions, prolonged vascular access, and the potential for nosocomial infections. Western Rajasthan in India is home to numerous teaching and training hospitals that cater to a large number of HD patients. Understanding the seroprevalence and genotypic distribution of HCV in this specific patient population is crucial for assessing the extent of infection within this vulnerable group for targeted surveillance and developing effectively tailored treatment protocolsin healthcare settings. Hence, this study was conducted with an aim to determine seroprevalence, seroconversion, and genotypes of HCV in HD patients at a tertiary care hospital. Methods This was a cross-sectional observational study. The duration of the study was from July 2019 to March 2022. In this study, the patients undergoing maintenance HD due to chronic kidney disease (CKD) were recruited. The data collected include patients' demographics, etiology of CKD, underlying other co-morbidities, duration of dialysis, and biochemical and blood count parameters. The patients recruited at the start of the study were screened for anti-HCV antibodies by HCV enzyme-linked immune sorbent assay (ELISA). The anti-HCV antibody-negative patients were followed up for the detection of anti-HCV antibodies. At the end of the follow-up period, all anti-HCV antibody negative samples in the pool of five and all anti-HCV antibody positive samples were subjected to a real-time polymerase chain reaction (RT-PCR) of 5' untranslated region (5'UTR) and core region, followed by line probe assay (LiPA). Results In this study, after applying inclusion and exclusion criteria, a total of 109 patients were recruited, out of which 64 (58.7%) were males and 45 (41.3%) were females. The age range of participants was 11-88 years with a mean and standard deviation of 46.75 and 16.35 years, respectively. A total of 39 patients (20 on screening, 19 on follow-up) were detected anti- HCV antibody positive. By RT-PCR, 24 patients tested HCV RNA positive (10 on screening, 14 on follow-up). Among 24 HCV RNA-positive samples, LiPA showed, HCV genotype 1a (n=21), genotype 3b (n=1), and two samples were detected to be inconclusive. Conclusion The increasing duration of dialysis is significantly associated with acquiring HCV infection. The majority of the cases of CKD in this geographical region are due to hypertensive nephropathy. There can be discordance between antibody and viral RNA positivity in HCV infection. The predominant HCV genotype identifiedin the dialysis ward of tertiary care hospital was genotype 1a.

Trends of drug resistance in M. tuberculosis in a reference laboratory in Central India: Forging ahead towards TB elimination

PurposeThe National Tuberculosis Elimination Programme (NTEP) of the Government of India has strived to control tuberculosis (TB) in the country through various interventions. Understanding the trends of resistance patterns may provide insights into the effectiveness of TB control activities in the country. MethodsA total of 31,144 clinical samples were received from 2013 to 2022 from presumptive drug-resistant TB patients. All the specimens were decontaminated and subjected to the line probe assay for detection of resistance to rifampicin and isoniazid. Mycobacterium tuberculosis (MTB) was detected in 28,814 samples. Autoregressive integrated moving average model (ARIMA) was fitted to assess the trend over time. ResultsA decreasing trend in multi-drug resistant TB from 19 % in 2013 to 4 % in 2022 was seen. A decreasing trend in rifampicin monoresistance from 11.2 % in 2013 to 1.5 % in 2022 was seen, though there was an increase in resistance in 2017. No significant decreasing trends were seen in the proportion of isoniazid monoresistance from 8.3 % in 2013 to 7 % in 2022. ConclusionThe findings are encouraging, and to a considerable extent, affirm that India is well on track with regard to the goal of TB elimination.

The Drug Susceptibility of Non-Tuberculous Mycobacteria (NTM) in a Referral Hospital in Rome from 2018 to 2023.

Background: The treatment of non-tuberculous mycobacterial (NTM) infections is challenging because of the difficulty in obtaining phenotypic (pDST) and/or molecular (mDST) drug susceptibility testing and the need of a multi-drug regimen. Objectives: The objective was to describe the in vitro susceptibility patterns of various NTM species through an analysis of susceptibility results obtained on isolates collected between 2018 and 2023. Methods: Species identification and mutations in rrs or rrl genes (mDST) were identified by a line probe assay, while the pDST was performed by broth microdilution and interpreted according to CLSI criteria. Results: We analysed 337 isolates of NTM belonging to 15 species/subspecies. The Mycobacterium avium complex (MAC) was the most common (62%); other species identified included M. gordonae (11%), M. kansasii (5%), the M. abscessus complex (8%), M. chelonae (6%), and M. fortuitum (2%). The results of pDST (claritromycin and amikacin) and mDST (rrl and rrs genes) on 66 NTM strains showed that while wild-type rrl and rrs occurred in 86.3% and 94% strains, respectively, the pDST showed 88% sensitivity for clarithromycin and 57.5% for amikacin. The main incongruity was observed for macrolides. Conclusions: Most NTM are likely to be susceptible to macrolides and aminoglycosides. The molecular identification of resistant genotypes is accurate and strongly recommended for optimal patient management.

Risk Factors Associated with Hepatitis C Subtypes and the Evolutionary History of Subtype 1a in Mexico.

The Hepatitis C Virus (HCV), with its diverse genotypes and subtypes, has significantly impacted the health of millions of people worldwide. Analyzing the risk factors is essential to understanding the spread of the disease and developing appropriate prevention strategies. This study aimed to identify risk factors associated with HCV subtype transmission and calculate the emergence time of subtype 1a in Mexico. A cross-sectional study was conducted from January 2014 to December 2018, involving 260 HCV-infected adults. HCV infection was confirmed via Enzyme-Linked Immunosorbent Assay, and viral load was measured by real-time PCR. Genotyping/subtyping tools were the Line Probe Assay and Sanger sequencing of the non-structural region 5B (NS5B). The most frequent HCV subtype was 1a (58.5%), followed by subtypes 1b (19.2%), 3a (13.1%), 2b (5.4%), 2a/2c (2.7%), 2a (0.8%), and 4a (0.4%). Intravenous drug use and tattoos were significant risk factors for subtypes 1a and 3a, while hemodialysis and blood transfusion were linked with subtype 1b. For the evolutionary analysis, 73 high-quality DNA sequences of the HCV subtype 1a NS5B region were used, employing a Bayesian coalescent analysis approach. This analysis suggested that subtype 1a was introduced to Mexico in 1976, followed by a diversification event in the mid-1980s. An exponential increase in cases was observed from 1998 to 2006, stabilizing by 2014. In conclusion, this study found that HCV subtypes follow distinct transmission routes, emphasizing the need for targeted prevention strategies. Additionally, the findings provide valuable insights into the origin of HCV subtype 1a. By analyzing the history, risk factors, and dynamics of the HCV epidemic, we have identified these measures: limiting the harm of intravenous drug trafficking, enhancing medical training and infrastructure, and ensuring universal access to antiviral treatments. The successful implementation of these strategies could lead to an HCV-free future in Mexico.

Evaluation of GeneNAT Real-Time Polymerase Chain Reaction Analyzer and Pre-loaded Chip-Based Mycobacterium tuberculosis and Multidrug-Resistant Tuberculosis Detection in the Diagnosis of Pulmonary Tuberculosis.

Tuberculosis (TB) is still the second causative agent of death worldwide after COVID-19. It is caused by Mycobacterium tuberculosis (MTB) infection. The aim of the current study was to compare the performance of GeneNAT real-time polymerase chain reaction analyzer and pre-loaded chip-based MTB screening and multidrug-resistant tuberculosis (MDR-TB) detection kit (Smart SureTM MTB & MDR-TB, Genetix Biotech Asia Pvt. Ltd., New Delhi, India) against the established WHO-approved GeneXpert Ultra (MTB/rifampicin (RIF)), line probe assay (LPA), and mycobacteriagrowthindicatortube(MGIT) culture at point of care (POC) level. A total of 450 pulmonary TB (PTB) suspect patients were enrolled from October 2023 to March 2024 at the Intermediate Reference Laboratory, Department of Medicine, All India Instituteof Medical Sciences, New Delhi, India. GeneXpert and GeneNAT tests were done directly from sputum specimens. However, processed sputum specimens were used for both LPA (GenoType MTBDRplus) and liquid culture and drug susceptibility testing (MGIT culture and drug susceptibility testing (DST)). On comparing with GeneXpert, for the detection of MTB and rifampicin (RIF), Smart SureTM showed a sensitivity of 98.18% and 97.5% with a specificity of 100% and 98.92%, respectively. While comparing mutations in therpoB gene with LPA, the Smart SureTM MDR-TB kit exhibited sensitivity and specificity of 96.77% and 99.12%, respectively. For katG and inhA genes, sensitivity and specificity were 97.6% & 85.71% and 98.66% & 98.01%, respectively, for both genes. Smart SureTM MDR-TB showed comparable results with MGIT-DST with sensitivity and specificity of 96.88% & 96.15% and 98.99%& 99.02%, respectively, for both RIF and isoniazid (INH) drugs. The GeneNAT system test may provide the status of RIF and INH resistance in PTB cases in a short time with the use of minimal specimens. It required very little infrastructurewith less skilled laboratory staffin comparison with other WHO-approved diagnostics used in resource-limited countries with TB and drug-resistant TB burdens.

TREATMENT OUTCOME OF TUBERCULOSIS CASES AMONG PAEDIATRIC PATIENTS IN WESTERN RAJASTHAN

Objective: This study aimed to identify drug-resistant tuberculosis cases and treatment results. Because it is one of the few studies that have looked at the results of TB treatment among children in the nation, this one was noteworthy. Methods: Drug-resistant cases of paediatric TB were recruited from various districts of Western Rajasthan. Drug resistance in Mycobacterium tuberculosis was detected by line Probe Assay. The cases were followed up for treatment. Results: A total of 41 drug-resistant TB cases were evaluated. Out of 41, 21 were rifampicin mono-resistant, 8 were isoniazid mono-resistant, MDR and pre-XDR were 5 each, and XDR cases were 2. 19 cases were successfully cured and there was one death reported during treatment. Conclusion: Cure rate of paediatric TB is less than 50% in our region. Adherence to treatment and contact isolation are crucial to increase cure rate and decrease the incidence of drug-resistant TB.

Non-tuberculous mycobacterium isolations from tuberculosis presumptive cases at the National Tuberculosis Reference Laboratory Kenya, 2018–2019

Background: Mycobacterial pathogens are among the top causes of diseases in humans. In Kenya, incidences of Non-Tuberculous Mycobacteria (NTM) species have steadily been on the increase. Most NTMare resistant to first line treatment of tuberculosis and have a challenge in timely and accurate diagnosis. Misdiagnosis has led to prescribing anti-tuberculosis regimens to patients suffering from NTM. We aimed to determine the most prevalent Non-Tuberculous Mycobacterium in Kenya. Methods: We reviewed records from the National Tuberculosis Reference Laboratory(NTRL ) Laboratory information management system (LIMS) between January 2018 and December 2019 for the patients on surveillance. All isolates were cultured in Mycobacterial Growth Indicator Tubes (MGIT) and incubated for detection using BACTEC™ MGIT™ system. Those with negative acid-fast bacilli (AFB) growth and negative for Mycobacterium Tuberculosis Complex Species (MTBC) protein-MPT64 were suggestive of NTM infections, which were sub-cultured in MGIT and characterized using Line Probe Assay (LPA) GenoType® MTBDR CM/AS. Descriptive and bivariate analysis was done. Results: Of the total 24,549 records reviewed, 167(0.7%) were NTM isolates. Males comprised of 74.2% (124/167), and the mean age was 42 years (SD±16), age group 35-44 years had the highest NTM at 26.3% (44/167). Nairobi had 12.6% (21/167), Mombasa 10.8% (18/167), Kilifi and Meru each had 7.8% (13/167). Eleven isolated species comprised of Mycobacterium intracellulare 35.3% (65/167), M. fortuitum at 27% (48/167), and M. scrofulaceum at 10.2% (17/167). Previously treated patients had higher NTM [63.5% (106/167)] than Drug-resistant follow-up patients [26.9% (45/167)]. Coinfection with HIV was at 27.5% (46/167). Conclusion: Previously treated patients should have an additional screening of NTMS, and drug susceptibility testing should be done before initiation of treatment.

Diagnostic accuracy of the Xpert® MTB/XDR assay for detection of Isoniazid and second-line antituberculosis drugs resistance at central TB reference laboratory in Tanzania

IntroductionEarly diagnosis of tuberculosis (TB) and universal access to drug-susceptibility testing (DST) are critical elements of the WHO End TB Strategy. Current rapid tests (e.g., Xpert® MTB/RIF and Ultra-assays) can detect rifampicin resistance-conferring mutations, but cannot detect resistance to Isoniazid and second-line anti-TB agents. Although Line Probe Assay is capable of detecting resistance to second-line anti-TB agents, it requires sophisticated laboratory infrastructure and advanced skills which are often not readily available in settings replete with TB. A rapid test capable of detecting Isoniazid and second-line anti-TB drug resistance is highly needed.MethodsWe conducted a diagnostic accuracy study to evaluate a new automated Xpert MTB/XDR 10-colour assay for rapid detection of Isoniazid and second-line drugs, including ethionamide, fluoroquinolones, and injectable drugs (Amikacin, Kanamycin, and Capreomycin). Positive Xpert MTB/RIF respiratory specimens were prospectively collected through routine diagnosis and surveillance of drug resistance at the Central TB Reference Laboratory in Tanzania. Specimens were tested by both Xpert XDR assay and LPA against culture-based phenotypic DST as the reference standard.FindingsWe analysed specimens from 151 TB patients with a mean age (SD) of 36.2 (12.7) years. The majority (n = 109, 72.2%) were males. The sensitivity for Xpert MTB/XDR was 93.5% (95% CI, 87.4–96.7); for Isoniazid, 96.6 (95% CI, 92.1–98.6); for Fluoroquinolone, 98.7% (95% Cl 94.8–99.7); for Amikacin, 96.6%; and (95% CI 92.1–98.6) for Ethionamide. Ethionamide had the lowest specificity of 50% and the highest was 100% for Fluoroquinolone. The diagnostic performance was generally comparable to that of LPA with slight variations between the two assays. The non-determinate rate (i.e., invalid M. tuberculosis complex detection) of Xpert MTB/XDR was 2·96%.ConclusionThe Xpert MTB/XDR demonstrated high sensitivity and specificity for detecting resistance to Isoniazid, Fluoroquinolones, and injectable agents. This assay can be used in clinical settings to facilitate rapid diagnosis of mono-isoniazid and extensively drug-resistant TB.