Are WHO approved nucleic acid amplification tests causing large-scale “false identification” of rifampicin-resistant tuberculosis?: Programmatic experience from south india

Introduction: The nucleic acid amplification tests (NAATs): Line probe assay and GeneXpert (Xpert) have evolved as the primary tool for identification of rifampicin (RIF)-resistant (RR) tuberculosis (TB) worldwide, primarily because of the ease and speed. We rechecked RR isolates identified by NAATs from presumptive RR TB cases belonging to South India by the Revised National TB Control Program, India using multiple RIF concentrations on Bactec MGIT system and compared the mutation patterns with the resistance levels. Methodology: Standard protocol for Bactec MGIT system as given by the manufacturer modified for the multiple RIF concentrations was used. All the retests were done in a certified BSL3 laboratory. Results: We found that there is a mismatch of up to 20% (RIF breakpoint 0.5 mg/L); the NAATs probably overidentifying RR TB. Half of the cases with mismatch showed a sub-breakpoint rise in resistance level (0.125 mg/L to 0.5 mg/L RIF). Discussion and Conclusion: The probable reasons for the mismatch are “sub-breakpoint low-level resistance mutants,” hetero-resistant bacterial populations, and other inherent test limitations along with the low RR TB prevalence in South India (<5%) among “presumptive multidrug-resistants.” This could be due to the incomplete selection pressure by an inadequate RIF exposure caused by various factors including a low-RIF dosage being used widely and poor Directly observed treatment. To prevent the false diagnosis of RR TB in a massive scale when using NAATs, we may need to enforce a carefully targeted testing approach and a phenotypic susceptibility testing with multiple RIF concentrations for confirmatory purposes

Predictable repeatability issues with GeneXpert-Xpert MTB/RIF (version 4) derived rifampicin resistant tuberculosis results from South India: Appreciating the limits of a technological marvel!

Background: GeneXpert MTB/RIF (Xpert), the fully automated cartridge-based nucleic acid amplification test for simultaneous identification of Mycobacterium tuberculosis complex and rifampicin resistance (RR), directly from samples is considered as a game changer for tuberculosis (TB) control programs worldwide. Methods: We are reporting serious issues with repeatability among a subgroup of Xpert (Version 4) identified RR results from South Indian state recently switched to Xpert by the National TB control program. Results: We have demonstrated that poor repeatability is frequently associated with those Xpert derived RR results, identified by detection of delayed amplification of any probe in the presence of positive analyte results for all probes. Another significant contributing factor was found to be lower bacterial loads in samples. The repeat tests were done by Xpert and/or by line probe assay depending on smear positivity. The finding is worrying as Xpert is recommended over other tests due to its reportedly better performance among low bacterial load samples such as pediatric, extra-pulmonary, HIV-TB co-infected, and smear negative pulmonary TB and the same samples, it seems are more likely to cause error prone RR results. Conclusions: We recommend for additional genotypic tests with specific mutant probes for detecting mutations at rpoB hot sites and growth based tests for all Xpert derived RR-TB cases identified by the above algorithm for confirmation of the presence of mutation, based on our available data

LC/MS-Based Profiling of <i>Hedyotis aspera</i> Whole-Plant Methanolic Extract and Evaluation of Its Nephroprotective Potential against Gentamicin-Induced Nephrotoxicity in Rats Supported by In Silico Studies

Many high-altitude plants, such as Hedyotis aspera, need to be explored for their possible medicinal value. The current study explored the protective effect of Hedyotis aspera methanolic extract whole plant (HAME) against gentamicin-induced nephrotoxicity in rats. It profiled their phytocontents using HPLC-QTOF-MS/MS analytic methods. The LC-MS analysis of HAME revealed 27 compounds. Eight compounds followed Lipinski’s rule of five and were found to be potential TNF-α inhibitors with binding affinities of −6.9, −6.3, −6.3, and −6.3 Kcal/mol, such as 14,19-Dihydroaspidospermatine, coumeroic acid, lycocernuine and muzanzagenin. All potential compounds were found to be safe according to the ADMET analysis. The in vitro 2,2-diphenyl-1-picrlhydrazyl (DPPH) assay assessed the antioxidant activity. The nephroprotective activity was assessed in rats using a gentamicin-induced nephrotoxicity model. The in vivo analysis involved histological examination, tissue biochemical evaluation, including a kidney function test, catalase activity (CAT), reduced glutathione (GSH) levels, superoxide dismutase (SOD), and the inflammatory mediator TNF-α. Based on DPPH activity, HAME showed a scavenging activity IC50 of 264.8 ± 1.2 µg/mL, while results were compared with a standard vitamin C IC50 of 45 ± 0.45 µg/mL. Nephrotoxicity was successfully induced, as shown by elevated creatinine and uric acid levels, decreased kidney antioxidant levels, and increased TNF-α in gentamicin-treated rats. The HAME treatment significantly reduced serum creatinine and uric acid levels, increased GSH (p p p p < 0.001 ***) in nephrotoxic rats. The histopathological examination of the groups treated with HAME revealed a notable enhancement in the structural integrity of the kidneys as compared to the group exposed to gentamicin. Biochemical, histopathological, and phytochemical screening of HAME suggests that it has nephroprotective potential, owing to the presence of 14,19-Dihydroaspidospermatine, coumeroic acid, lycopene, and muzanzagenin

Recurrence of tuberculosis among newly diagnosed sputum positive pulmonary tuberculosis patients treated under the Revised National Tuberculosis Control Programme, India: A multi-centric prospective study

<div><p>Introduction</p><p>There is lack of information on the proportion of new smear—positive pulmonary tuberculosis (PTB) patients treated with a 6-month thrice-weekly regimen under Revised National Tuberculosis Control Programme (RNTCP) who develop recurrent TB after successful treatment outcome.</p><p>Objective</p><p>To estimate TB recurrence among newly diagnosed PTB patients who have successfully completed treatment and to document endogenous reactivation or re-infection. Risk factors for unfavourable outcomes to treatment and TB recurrence were determined.</p><p>Methodology</p><p>Adult (aged ≥ 18 yrs) new smear positive PTB patients initiated on treatment under RNTCP were enrolled from sites in Tamil Nadu, Karnataka, Delhi, Maharashtra, Madhya Pradesh and Kerala. Those declared “treatment success” at the end of treatment were followed up with 2 sputum examinations each at 3, 6 and 12 months after treatment completion. MIRU-VNTR genotyping was done to identify endogenous re-activation or exogenous re-infection at TB recurrence. TB recurrence was expressed as rate per 100 person-years (with 95% confidence interval [95%CI]). Regression models were used to identify the risk factors for unfavourable response to treatment and TB recurrence.</p><p>Results</p><p>Of the1577 new smear positive PTB patients enrolled, 1565 were analysed. The overall cure rate was 77% (1207/1565) and treatment success was 77% (1210 /1565). The cure rate varied from 65% to 86%. There were 158 of 1210 patients who had TB recurrence after treatment success. The pooled TB recurrence estimate was 10.9% [95%CI: 0.2–21.6] and TB recurrence rate per 100 person–years was 12.7 [95% CI: 0.4–25]. TB recurrence per 100 person–years varied from 5.4 to 30.5. Endogenous reactivation was observed in 56 (93%) of 60 patients for whom genotyping was done. Male gender was associated with TB recurrence.</p><p>Conclusion</p><p>A substantial proportion of new smear positive PTB patients successfully treated with 6 –month thrice-weekly regimen have TB recurrence under program settings.</p></div

Treatment outcome of new smear positive pulmonary TB patients [N = 1565].

<p>Treatment outcome of new smear positive pulmonary TB patients [N = 1565].</p

Risk factors for unfavourable response at the end of treatment in new smear positive pulmonary TB patients [N = 1543].

<p>Risk factors for unfavourable response at the end of treatment in new smear positive pulmonary TB patients [N = 1543].</p

Study sites for the recurrence of TB among the newly diagnosed sputum positive pulmonary TB patients treated under RNTCP in India.

<p>Study sites for the recurrence of TB among the newly diagnosed sputum positive pulmonary TB patients treated under RNTCP in India.</p

Status at 12 months after Treatment success in new smear positive pulmonary TB patients [N = 1210].

<p>Status at 12 months after Treatment success in new smear positive pulmonary TB patients [N = 1210].</p

Details of TB recurrence in new smear positive pulmonary TB patients [N = 158].

<p>Details of TB recurrence in new smear positive pulmonary TB patients [N = 158].</p

Details on screening, enrolment and follow-up for TB recurrence in new smear positive pulmonary TB patients under RNTCP.

<p>Details on screening, enrolment and follow-up for TB recurrence in new smear positive pulmonary TB patients under RNTCP.</p