A dual strain probiotic administered via the waterline beneficially modulates the ileal and cecal microbiome, sIgA and acute phase protein levels, and growth performance of broilers during a dysbacteriosis challenge

Intestinal dysbacteriosis is increasing in broilers due to the reduced use of antibiotics in feed. This study tested the effect of daily waterline administration of a dual-strain probiotic comprising Lactobacillus acidophilus AG01 and Bifidobacterium animalis subspecies lactis AG02, on growth performance and intestinal health during a 3-step microbial challenge. In total, 900 Ross 308 males were assigned to 36 floor pens (25 birds/pen, 12 pens/treatment) in a completely randomized design. Birds were fed a corn, wheat and soybean-meal based diet. Diets were formulated in 3 phases (starter: 1 to 10; grower: 11 to 24; finisher: 25 to 42 d of age). Treatments comprised a non-challenged control (NC), challenged control (CC), and the CC supplemented with 1 × 108 colony forming units (CFU)/bird/day of the probiotic (CC+Probiotic). The challenge comprised 1 × 108 CFU/bird of Avian Pathogenic Escherichia coli on d 7, 4,000 oocysts/bird of Eimeria on d 15 and 1 × 109 CFU/bird of C. perfringens on d 18, 19 and 20. Growth performance was monitored over 42 d, blood samples, and digesta were collected and intestinal dysbacteriosis scoring was performed. Compared to NC birds, CC birds exhibited reduced BW (all phases), reduced feed intake (starter and grower phase), increased FCR (grower phase and overall; P < 0.05), reduced ileal lactic acid bacteria concentrations (d 24 and 42), and increased cecal E. coli (d 24; P < 0.05). Compared to CC birds, CC+Probiotic birds exhibited increased BW, BW gain and feed intake during grower phase (P < 0.05), increased ileal lactic acid bacteria at d 24 and 42 and reduced ileal C. perfringens at d 24, increased mucosal secretory IgA and reduced serum alpha-1-acid-glycoprotein at d 42. The overall growth performance of CC+Probiotic birds was equivalent to NC birds. These results confirm the efficacy of the dual strain probiotic for mitigating the negative effects of a multi-microbial challenge, improving gut health and growth performance in commercial broilers under dysbacteriosis challenge.

Operational feasibility and multi-centric evaluation of 'TBDetect sputum microscopy kit' for the direct detection of Mycobacterium tuberculosis in field settings

BACKGROUND

India relies primarily on direct smear microscopy for tuberculosis (TB) diagnosis. However, the low sensitivity of smear microscopy emphasizes the need to improve its performance. We recently described the development of 'TBDetect' kit which showed improved performance over direct smear microscopy at National Reference Laboratories (NRLs) in India.

METHODS

The present study was aimed to assess the operational feasibility of 'TBDetect' microscopy in field settings. This was evaluated by (i) assessing the performance of 'TBDetect' microscopy vs. LED-fluorescence microscopy (LED-FM) on consecutive presumptive pulmonary TB patients (n = 5300) who attended Designated Microscopy Centres (DMCs, n = 13) under 4 NRLs at Bhubaneswar, Bhopal, Chennai, and New Delhi, and (ii) obtaining feedback from Scientists (n = 10) and laboratory technicians (n = 42) using semi-structured questionnaires under the following parameters: feasibility of initiation of 'TBDetect' microscopy in DMCs, sample preparation and testing, training, time-to-result, logistics, and troubleshooting. A scoring questionnaire was also used to assess 'TBDetect' microscopy vs. LED-FM and statistical significance of the scores was calculated using paired t-test.

RESULTS

The overall positivity of 'TBDetect' microscopy was 10.32% (547/5300) vs. 8.96% (475/5300) of LED-FM at all sites and the increment in positivity was significant (p = 0.019). In addition, 'TBDetect' microscopy yielded an increment in smear grade status over LED-FM (p = 0.043). The feedback from the study-in-charge and kit users indicated that 'TBDetect' microscopy was easily adapted in point-of-care settings. An analysis of scoring feedback suggested that it was easy to perform and observe in comparison to LED-FM (p < 0.005).

CONCLUSIONS

This study established the feasibility of 'TBDetect' microscopy in field settings.

Dose to Organ at Risk and its Characteristic Variation with the Clinically Used Different Prescription Levels for Early-stage Left-sided Breast Cancer

AIMS

To evaluate the organ at risk (OAR) dose and its characteristic variation with different clinically usable prescription doses (RxD) for breast and chest wall radiotherapy in patients with early-stage left-sided breast cancer.

MATERIALS AND METHODS

In total, 145 patients with early-stage breast cancers (T1N0M0-T2N0M0) on the left side were treated with radiotherapy after a modified radical mastectomy or breast conservation surgery, with a mean age of 45.1 ± 21.6 years. The patient received 4050 cGy of field-in-field (three-dimensional conformal radiotherapy) treatment limited to the breast or chest wall, excluding the supraclavicular node, axillary node and internal mammary chain, over 15 fractions. Additional plans of 5000 cGy/25 fractions, 4500 cGy/20 fractions and 2600 cGy/5 fractions were created with no or minor changes to the original plan. Mathematical modelling was used to study the distinctive change in the dose-volume characteristics for various OARs as a function of the RxD. OAR dosages, both absolute and normalised, were expressed in terms of the RxD. The mathematical (functional) relationship between OAR doses and different prescription levels was deduced by the least squares fit method.

RESULT

The left lung mean dose, V5Gy (%), V10Gy (%) and V20Gy (%) and the heart mean dose, V10Gy (%) and V20Gy (%) were evaluated. The dose-volume parameters showed a parabolic variation (x2) with the RxD. Prescription normalised OAR doses showed a linear relationship with the RxD; relative dose increased with diminishing RxD. Normalised lung and heart mean doses exhibited saturation (linear relationship) with RxD variation. Paired sample t-test results between RxD versus all evaluated parameters were found to be statistically significant (P = 0.004). The Pearson correlation coefficient between different prescription levels for left lung mean dose (range 0.942-1.0), heart mean dose (range 1.0-1.0), left lung V5Gy (%) (range 0.987-1.0), left lung V10Gy (%) (range 0.991-0.999), heart V10Gy (%) (range 0.998-1.0).

CONCLUSION

The functional form of absolute OAR dose-volume parameters versus RxD is parabolic and the RxD normalised OAR dose-volume parameter versus RxD is a straight line with a negative slope as RxD increases. This indicates an increase in the relative OAR dose-volume parameters if the RxD is reduced. This study is the first of its kind to compare the OAR doses as a function of clinically used degenerate prescription levels. These data will help to comprehend the OAR doses while adopting a new dose fractionation regimen and reviewing the radiotherapy treatment plans.

Direct Detection of Fluoroquinolone Resistance in Sputum Samples from Tuberculosis Patients by High Resolution Melt Curve Analysis

Multidrug-resistant tuberculosis (MDR-TB) requires treatment with fluoroquinolone (FLQ) drugs, however, the excessive use of FLQ has led to the rise of extensively drug-resistant TB. In 2019, ~ 20% of total MDR-TB cases were estimated to be resistant to FLQ drugs. In the present study, we developed and evaluated the utility of high-resolution melt curve analysis (HRM) for the rapid detection of FLQ-resistant Mycobacterium tuberculosis for the first time directly from sputum samples. A reference plasmid library was generated for the most frequently observed mutations of gyrA gene and was used to discriminate between mutant and wild-type samples in the FLQ-HRM assay. The developed assay was evaluated on n = 25 MDR M. tuberculosis clinical isolates followed by validation on archived sputum DNA (n = 88) using DNA sequencing as a gold standard. The FLQ-HRM assay showed a 100% sensitivity [95% Confidence Interval (CI): 71.5 to 100] and specificity (95% CI: 39.7 to 100) in smear-positive category, and a sensitivity of 88.9% (95% CI: 77.3 to 95.8) with 84.2% (95% CI: 60.4 to 96.6) specificity in smear-negative category. The assay showed a high level of concordance of ~ 90% (κ = 0.74) with DNA sequencing, however, we were limited by the absence of phenotypic drug susceptibility testing data. In conclusion, HRM is a rapid, cost-effective (INR 150/USD 1.83) and closed-tube method for direct detection of FLQ resistance in sputum samples including direct smear-negative samples.

Evaluation of Mycobacterium tuberculosis derived cell-free DNA using pleural fluid and paired plasma samples for the diagnosis of pleural tuberculosis

Pleural tuberculosis (pTB) is a grave clinical challenge. A novel cell-free M. tuberculosis DNA (cfM.tb-DNA) probe-based-qPCR assay was developed for the diagnosis of pTB. Total cell-free DNA was extracted from pleural fluid (PF) and paired plasma samples and cfM.tb-DNA was quantified by probe-based qPCR targeting devR (109-bp) gene of M. tuberculosis in patients with pleural effusion. Patient categorization was done using 'Composite-Reference-Standard' formulated for the study. Assay cut-offs were determined from samples in the 'Development set' (n = 17; 'Definite & Probable' pTB; n = 9 and 'Non-TB'; n = 8) by ROC-curve analysis and applied to 'Validation set' (n = 112; 'Definite' pTB; n = 8, 'Probable' pTB; n = 34, 'Possible' pTB; n = 28 and 'Non-TB'; n = 42). cfM.tb-DNA qPCR had a sensitivity of 62.5% (95%CI; 24.4,91.4) in 'Definite' pTB category and 59.5% (95%CI; 43.2,74.3) in 'Definite & Probable' pTB category with 95.2% (95%CI; 83.8,99.4) specificity using PF. In plasma (n = 85), the assay had a sub-optimal sensitivity of 7.6% (95%CI; 0.95,25.1) with 88.2% (95%CI; 72.5,96.7) specificity in 'Definite & Probable' pTB group. Xpert MTB/RIF assay detected only six-samples in the 'Validation set'. Logistic regression analysis indicated that PF-cfM.tb-DNA qPCR provided incremental advantage over existing pTB diagnostic algorithms. To the best of our knowledge, this is the first report describing the utility of cfM.tb-DNA for pTB diagnosis in India.

MPT51 and MPT64-based antigen detection assay for the diagnosis of extrapulmonary tuberculosis from urine samples

In view of WHO's "End-TB" strategy, we developed a non-invasive, urine-based ELISA, targeting 2 Mycobacterium tuberculosis antigens namely MPT51 and MPT64 for extrapulmonary TB (EPTB) diagnosis. Suspected EPTB patients (n = 137) [Pleural TB, Abdominal TB and Tuberculous meningitis] were categorized in "Definite" EPTB (n = 10) [Xpert-MTB/RIF and/or culture-positive], "Probable" EPTB (n = 77) and "Non-EPTB" (n = 50) groups using defined composite reference standards. ROC-curves were generated using ELISA results of "Definite" EPTB and "Non-EPTB" groups for both antigens independently and cut-off values were selected to provide 86.3% (95%CI:73.3-94.2) specificity for MPT51 and 92% (95%CI:80.8-97.8) for MPT64. The sensitivity of MPT51-ELISA and MPT64-ELISA was 70% (95%CI:34.7-93.3) and 90% (95%CI:55.5-99.7) for "Definite" EPTB group and 32.5% (95%CI:22.2-44.1) and 30.8% (95%CI:20.8-42.2) for "Probable" EPTB group, respectively. Combining the results of both ELISAs showed a 100% (95%CI:69.1-100) sensitivity in "Definite" EPTB group and 41.6% (95%CI:30.4-53.4) in "Probable" EPTB group, with an 80% (95%CI:66.3-89.9) specificity. The results demonstrated the potential of urine-based ELISAs as screening tests for EPTB diagnosis.

Novel biomarkers predict ablation outcomes in long stranding persistent atrial fibrillation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHR

Background

Ablation of long-standing persistent atrial fibrillation (LSPAF) is not always successful. The arrhythmia burden was reduced by 75% by 12 months in majority (72%) of patients with LSPAF who underwent surgical or percutaneous ablation in the CASA-AF trial. We hypothesised that biomarker(s) improve prediction of clinical success and offer insights into mechanisms.

Objective

To identify biomarkers that predict success (75% arrhythmia burden reduction) after ablation for LSPAF at 12-months.

Methods

Amongst patients participating in the CASA-AF RCT (ISRCTN18250790), pre-ablation serum samples were selected for 20 patients who met criteria for ablation-success at 12 months, and 20 who did not. Olink ProteomicsTM (Sweden) provided analyses using three biomarker panels [inflammation (INFL), cardiovascular III (CVD III), and cell cytology (CELL)] each containing 92 biomarkers. Univariate and multivariable analyses were adjusted for age, sex, BMI, LA diameter and CRP. ROC analysis was undertaken to assess the diagnostic accuracy of the biomarkers. To counter the false discovery rate, Benjamini-Hochberg correction was utilised.

Results

When patients with ablation-success and -failure were compared, no differences in demographics or cardiac function were found. On univariate analysis, several biomarkers in each panel were associated with ablation-success. Multivariable analysis narrowed the range of biomarkers and identified those that were jointly predictive of outcome: INFL (MCP1 + CD8A + CD40, Figure 1), CVD III (FAS + CPB1) and CELL (GCG + ENTPD6 + IL17RB). These joint biomarkers were analysed using ROC (Figure 2), which showed that increases of biomarkers on the INFL panel (MCP1 + CD8A + CD40) were associated with a greater risk of failure and achieved the highest AUC for prediction of outcome [0.82 (0.75-0.87)].

Conclusion

The increase in the serum concentration of markers of inflammation (MCP1 + CD8A + CD40) might be used to identify patients less likely to have sustained benefit from LSPAF ablation. Further studies are required to confirm their prognostic value as pre-procedural biomarkers.

The acute haemodynamic response with endocardial biventricular pacing: comparing RV paced and LBBB patients

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Boston Scientific

Background

A third of patients that receive cardiac resynchronisation (CRT) are non-responders. Predictors of positive response include broader QRS duration, non-ischaemic aetiology and sinus rhythm, but it is still unclear whether lead placement site determines a positive responder.

Purpose

We assessed the acute haemodynamic response of endocardial biventricular pacing in patients with intrinsic left bundle brunch block (LBBB) versus LBBB due to pre-existing right ventricular pacing (RVP).

Methods

Patients who fulfilled standard criteria for CRT implantation but had failed conventional (coronary sinus) left ventricular (LV) lead placement (primary or revision) or were deemed clinical ‘non-responders after &gt; 6 months of conventional CRT were enrolled. The acute haemodynamic response during endocardial biventricular pacing was assessed with a roving LV lead at 9 different locations (basal and mid: septal, anterior, posterior and lateral walls and apex). Acute changes in beat-to-beat systolic blood pressure (SBP) in the left ventricle were recorded and analysed.

Results

We recruited 23 patients across 10 UK centres: 14 intrinsic LBBB and 9 dependent on RVP. Patient characteristics were comparable: age (mean 67 + 10.6 years vs. 62 + 15.4 years), ischaemic (63% vs 50%), QRS (160 + 18ms vs. 190 + 36ms, p =0.07). Of the RVP group 5/9 had septal RV leads (the remainder apically positioned).

There was no difference in the SBP improvement between the groups: change in SBP ranged from -5.25 – 19.91mmHg (median 3mmHg) in RVP patients vs -5.92 – 23.03mmHg (median 3mmHg) for intrinsic LBBB. However, the improvement in SBP was more consistent across the different segments in the patients with RVP (group A), as compared to intrinsic LBBB (group B), where the lateral wall and then non-septal walls provided the greatest haemodynamic improvement.

Figure 1: depicts SBP improvement (in mmHg) during endocardial biventricular pacing in different positions within the LV for patients with RVP (A) vs underlying intrinsic LBBB (B): 9 segment model of the LV: Ant (anterior wall), Lat (lateral wall), Post (posterior wall), Sept (septum). Outer ring represents the four basal LV locations, middle ring the mid LV locations and centre ring the apex. Scale depicts mmHg improvement in SBP.

Conclusion

When implanting an LV lead for patients who are RV pacing dependent any position within the LV provides an acute haemodynamic improvement, compared with those with intrinsic LBBB, where a targeted lateral wall approach is more important. This finding corroborates the key differences in LV activation patterns for induced versus intrinsic LBBB.

Direct Molecular Detection of Drug-Resistant Tuberculosis from Transported Bio-Safe Dried Sputum on Filter-Paper

In 2019, amongst half a million new rifampicin-resistant tuberculosis (TB) cases, 78% were multi drug-resistant TB (MDR-TB). Access to rapid and Universal-Drug susceptibility testing (DST) to patients in remote areas is a major challenge to combat drug-resistant TB. To overcome this challenge, we had recently reported the development of 'TB Concentration & Transport kit' for bio-safe ambient temperature transport of dried sputum on filter-paper (Trans-Filter). The present study was conducted to evaluate the utility of DNA extracted from sputum on Trans-Filter in a Multiplex PCR-based sequencing assay (Mol-DSTseq) for diagnosing drug-resistant TB. The developed Mol-DSTseq assays were standardized on Mycobacterium tuberculosis clinical isolates (n = 98) and further validated on DNA extracted from sputum on Trans-Filter (n = 100). Using phenotypic DST as gold standard, the Mol-DSTseq assay showed 100% (95% Confidence Interval [CI] 79.4-100%) and 73.3% (95% CI 54.1-87.7%) sensitivity for detecting rifampicin and isoniazid resistance with a specificity of 85.1% (95% CI 66.2-95.8%) and 100% (95% CI:82.3-100%), respectively. For fluoroquinolones and aminoglycosides, the Mol-DSTseq assay showed a sensitivity of 78.5% (95% CI 49.2-95.3%) and 66.6% (95% CI 9.4-99.1%) with a specificity of 88.2% (95% CI 72.5-96.7%) and 100% (95% CI 93.1-100%), respectively. The Mol-DSTseq assays exhibited a high concordance of ~ 83-96% (κ value: 0.65-0.81) with phenotypic DST for all drugs. In conclusion, the 'TB Concentration and Transport kit' was compatible with Mol-DSTseq assays and has the potential to provide 'Universal-DST' to patients residing in distant areas in high burden countries, like India for early initiation of anti-tubercular treatment.

Compatibility of a novel filter paper-based bio-safe sputum transport kit with line probe assay for diagnosing drug-resistant tuberculosis: a single-site evaluation study

Background

Near-patient access to appropriate tests is a major obstacle for the efficient diagnosis of tuberculosis (TB) and associated drug resistance.

Methods

We recently developed the “TB Concentration & Transport” kit for bio-safe, ambient-temperature transportation of dried sputum on Trans-Filter, and the “TB DNA Extraction” kit for DNA extraction from Trans-Filter for determining drug resistance by DNA sequencing. In the present study, we evaluated the compatibility of Kit-extracted DNA with Hain's line probe assays (LPAs), which are endorsed by National TB programmes for the detection of drug resistance in sputum collected from presumptive multidrug-resistant TB patients (n=207).

Results

Trans-Filter-extracted DNA was seamlessly integrated with the LPA protocol (Kit-LPA). The sensitivity of Kit-LPA for determining drug resistance was 83.3% for rifampicin (95% CI 52–98%), 77.7% for isoniazid (95% CI 52–94%), 85.7% for fluoroquinolones (95% CI 42–100%) and 66.6% for aminoglycosides (95% CI 9–99%), with a specificity range of 93.7% (95% CI 87–97) to 99.1% (95% CI 95–100) using phenotypic drug susceptibility testing (DST) as a reference standard. A high degree of concordance was noted between results obtained from Kit-LPA and LPA (99% to 100% (κ value: 0.83–1.0)).

Conclusions

This study demonstrates successful integration of our developed kits with LPA. The adoption of these kits across Designated Microscopy Centres in India can potentially overcome the existing challenge of transporting infectious sputum at controlled temperature to centralised testing laboratories and can provide rapid near-patient cost-effective “Universal DST” services to TB subjects residing in remote areas.

The adoption of bio-safe “TB Concentration & Transport” kit by Microscopy Centres can potentially overcome the challenge of transporting infectious sputum to central laboratories and provide universal DST services to TB subjects residing in remote areas.https://bit.ly/2QrQ5qL

Atrial fibrillation substrate mapping with decrement evoked potential mapping

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Sociedad Española de Cardiologia.

OnBehalf

DEFINE-AF

Background

Identifying and targeting atrial substrate zones that are vulnerable to unidirectional block and slow conduction may be critical to improve the outcomes of atrial fibrillation (AF) ablation. Functional mapping of the atrial substrate with Decrement Evoked Potential (DeEP) and a single extrastimulus in this population could potentially lead to novel therapeutic strategies.

Aim

1) To systematically analyze whether the DEEP are present in the atrial tissue and their locations after pulmonary vein isolation. 2) To assess their relationship with the underlying voltage.  3) To assess the presence of DEEP as a function of the subtype of AF.

Methods

Consecutive patients with AF undergoing ablation were prospectively enrolled at 3 institutions. A biatrial voltage map was created and after pulmonary vein isolation (PVI). A drive train and an extrastimulus (atrial refractory period + 20ms) was delivered from an epicardial site (proximal CS) and an endocardial site (left atrial appendage (LAA). A multipolar mapping catheter was sequentially placed at 8 left atrial sites and 5 right atrial sites. Electrograms (EGMs) that showed a local delay of &gt;10ms in activation with the extrastimulus were identified as DEEPs. Patients were followed for a mean of 11 ± 5 months

Results

74 patients, 63 pers AF (85%), mean age 62 ± 8, mean LA size 41 ±12 mm were enrolled. Of 19240 EGMs analyzed, 8.2% showed DEEPs (54.6% with CS pacing and 45.4% with LAA pacing, p = 0.0001). The mean local decrement seen was 39 ms. Most DEEPs (76.2%) were identified in sites with a normal EGM at baseline with preserved voltages. DEEPs were differentially distributed within the regions mapped, more frequently in LA than RA (9.2% vs 6.6%, p &lt; 0.0001). Patients with persistent AF had a higher proportion of DEEPs than patients with paroxysmal AF (9.7% vs 5.1%, p &lt; 0.001).

Conclusions

Atrial DEEPs are: 1) More often identified when pacing endocardially. 2) More common in patients with persistent AF. 3) More frequent in the LA than in the RA. 4) Mostly located in regions with normal voltages at baseline. All those findings suggest the importance of the functional substrate mapping in the atrium and could lead to novel therapeutic targets. Abstract Figure. Example of atrial DEEP

Evaluation of 'TBDetect' sputum microscopy kit for improved detection of Mycobacterium tuberculosis: a multi-centric validation study

OBJECTIVES

The present study aimed to evaluate the performance of the 'TBDetect' kit-based bio-safe fluorescent microscopy filter (BioFM-Filter) microscopy in comparison with direct smear microscopy and culture for the detection of pulmonary tuberculosis (TB) in a multi-centric setting in India.

METHODS

The TBDetect kit enables sputum concentration through filtration using the BioFM-Filter for improved and bio-safe smear microscopy. We evaluated the performance of the TBDetect kit in a six-site multi-centric validation study on sputum collected from 2086 presumptive TB patients.

RESULTS

The combined positivity of TBDetect microscopy performed on these sputum samples was 20% (n = 417/2086) vs 16.1% of light-emitting diode fluorescence microscopy (LED-FM, n = 337/2086) and 16% of Ziehl Neelsen (ZN) smear microscopy (n = 333/2086). The increment in positivity of TBDetect over both LED-FM and ZN smears was significant (p < 0.001). The overall sensitivity of TBDetect for six sites was ~55% (202/367, 95% confidence interval (CI): 50, 60%) vs 52% (191/367, 95% CI: 47, 57%) for LED-FM (p 0.14) and 50.9% (187/367, 95% CI: 46, 56%) for ZN smear (p < 0.05), using Mycobacterium Growth Indicator Tube culture (MGIT, n = 1949, culture positive, n = 367) as the reference standard. A bio-safety evaluation at six sites confirmed efficient sputum disinfection by TBDetect; 99.95% samples (1873/1874) were sterile after 42 days of incubation. Scientists and technicians at the study sites indicated the ease of use and convenience of TBDetect microscopy during feedback.

CONCLUSIONS

TBDetect added value to the smear microscopy test due to its improved performance, convenience and user safety. These findings indicate that equipment-free TBDetect technology has the potential to improve TB diagnosis in basic laboratory settings by leveraging on the existing nationwide network of designated microscopy centres and primary healthcare centres.

Brown fat activity determined by infrared thermography and thermogenesis measurement using whole body calorimetry (BRIGHT Study)

To assess BAT activity in humans at a population level, infrared thermography (IRT) represents a safe, readily repeatable and affordable alternative to 18F-FDG-PET. Building upon a previously proposed method by our laboratory, we further refined the image computational algorithm to quantify BAT activation in the cervical-supraclavicular (C-SCV) region of healthy young men under thermo-neutral and cold exposure conditions. Additionally, we validated the whole-body calorimeter (WBC) in reliably measuring cold-induced thermogenesis. The temperature gradient between C-SCV-deltoid regions, and the corresponding difference in heat power output, increased upon cold air exposure relative to thermo-neutral conditions (by 74.88 %, p<0.0001; and by 71.34 %, p<0.0001 respectively). Resting and cumulative energy expenditure (EE) rose significantly (by 13.14 % and 9.12 % respectively, p=0.0001) while positive correlations between IRT measures and EE were found with cold air exposure (percentage change in heat power gradient between ROI and deltoid, cold air: r(2)=0.29, p=0.026, Pearson's correlation). IRT and WBC can be used to study BAT activation. The refined algorithm allows for more automation and objectivity in IRT data analysis, especially under cold air exposures.

Theranostic Application of a Novel G-Quadruplex-Forming DNA Aptamer Targeting Malate Synthase of Mycobacterium tuberculosis

The successful management of tuberculosis (TB) requires efficient diagnosis and treatment. Further, the increasing prevalence of drug-resistant TB highlights the urgent need to develop novel inhibitors against both drug-susceptible and drug-resistant forms of disease. Malate synthase (MS), an enzyme of the glyoxylate pathway, plays a vital role in mycobacterial persistence, and therefore it is considered as an attractive target for novel anti-TB drug development. Recent studies have also ascribed an adhesin function to MS and established it as a potent diagnostic biomarker. In this study, a panel of Mycobacterium tuberculosis (Mtb) MS-specific single-stranded DNA aptamers was identified by Systematic Evolution of Ligands by EXponential enrichment (SELEX). The best-performing G-quadruplex-forming 44-mer aptamer, MS10, was optimized post-SELEX to generate an 11-mer aptamer, MS10-Trunc. This aptamer was characterized by various biochemical, biophysical, and in silico techniques. Its theranostic activity toward Mtb was established using enzyme inhibition, host cell binding, and invasion assays. MS10-Trunc aptamer exhibited high affinity for MS (equilibrium dissociation constant [K_D] ∼19 pM) and displayed robust inhibition of MS enzyme activity with IC₅₀ of 251.1 nM and inhibitor constant (K_i) of 230 nM. This aptamer blocked mycobacterial entry into host cells by binding to surface-associated MS. In addition, we have also demonstrated its application in the detection of tuberculous meningitis (TBM) in patients with sensitivity and specificity each of >97%.

P2831Safety of atrial fibrillation catheter ablation in the elderly

Background

Catheter ablation for drug refractory, symptomatic atrial fibrillation (AF), is becoming increasingly common and can be beneficial in alleviating symptoms. However, in the elderly, there are concerns about the risks an invasive procedure poses, with limited published data available in those aged over 80 years.

Purpose

To determine the complication risk of AF catheter ablation in the elderly

Methods

Complications were identified from patient records in 3156 consecutive patients who underwent radiofrequency catheter ablation for AF, at a tertiary cardiology centre between 2013–2017. All cases were performed under general anesthesia.

Results

In this cohort of 3156 patients (mean age= 62.9±11.0 years, female = 29.9%), 90 (2.85%) (mean age= 66±10.0 years, female = 49.5%) complications were identified. In patients aged ≥80 years, complications occurred in 5 out of 99 patients (5.05%) (mean age= 82.6±1.2, female=100%), compared to 85 out of 3057 patients (2.78%) in those aged <80 years (mean age= 65±10.3, female = 49.4%). The difference was not significant p=0.18. Complications in the elderly all occurred acutely, and included groin haematoma (2.02%), pneumonia (2.02%) and pericardial effusion (1.01%).

Conclusion

Catheter ablation for AF in patients ≥80 years of age, is not associated with a significant increase in complication risk, compared to those who are younger.

P978Core to block: a new ablation strategy for treating persistent atrial fibrillation

Background

Ablation strategy targeting the core of atrial fibrillation (AF) rotors alone can lead to both stabilisation and destabilisation of rotational activity. Non-contact dipole density mapping system is designed to rapidly identify dynamic regional atrial activation patterns of interest (API) during AF.

Purpose

To assess the feasibility of an ablation strategy consisted of pulmonary vein isolation + targeting the core of APIs followed by linear ablation to the nearest non-conducting boundary to treat persistent AF.

Methods

The ablation strategy includes: 1. Antral pulmonary vein electrical isolation (APVI); 2. APIs (focal, localised rotational and localised irregular activation; Figure1) detection by dipole density mapping; 3. API core ablation followed by linear ablation to the nearest non-conduction barrier (APVI/mitral valve); 4. repeat step 2 and 3 in LA (RA, if necessary) until sinus rhythm is achieved.

Results

Consecutive 40 persistent AF patients (mean 62±12 years, 29 males, AF duration 10±4 months, LA diameter 42±9 mm) were included from 2 centres. An average of 2.0±0.7 APIs per patient were targeted post-APVI. Acute AF termination by ablation was achieved in 27/40 (68%) patients. The mean ablation time of APVI and “Core to block” was 33±12 mins and 31±22 mins, respectively. No major complication occurred. During a mean follow-up of 12±5 months, 32/40 patients (80%) maintained sinus rhythm.

Conclusion

APVI + “Core to block” guided by the dipole density mapping is feasible for treating persistent AF. A larger randomised study is needed to test the effectiveness of this ablation strategy.

Acknowledgement/Funding

None

P3756Diverse activation patterns during persistent atrial fibrillation characterised by dipole density non-contact mapping

Background

Global simultaneous recording of activation during atrial fibrillation (AF) can elucidate underlying mechanisms contributing to AF maintenance. A better understanding of these mechanisms may allow for a personalised ablation strategy to treat persistent AF.

Purpose

To characterise left atrial endocardial activation patterns during AF using a novel non-contact dipole density mapping.

Methods

Activation patterns were characterised into three sub-types: (i) focal with centrifugal activation (FCA); (ii) localised rotational activation (LRA); (iii) localised irregular activation (LIA). Continuous activation patterns were quantified and distributed in the left atrium.

Results

A total of 144 persistent AF segments with 1068 activation patterns from 25 patients were analysed. The most common pattern was LIA (63%), which consist of four disparate features: slow conduction (45%), pivoting (30%), collision (16%) and acceleration (7%). LRA was the second commonest pattern (20%). FCA (17%) arose frequently from the PVs/ostia. Continuous AF activations comprise multiple combinations of FCA, LRA and LIA, transitioning from one to the next without a discernible order. Preferential conduction areas were typically seen in mid-anterior (48%) and lower-posterior (40%) walls where dominant activations were made up of LRA and LIA.

Conclusion

AF is characterised by heterogenous activation patterns that vary between individuals. Clinical implications of individualised ablation strategies guided by dipole density mapping will have to be determined.

Acknowledgement/Funding

None

Development and evaluation of novel bio-safe filter paper-based kits for sputum microscopy and transport to directly detect Mycobacterium tuberculosis and associated drug resistance

India has the highest burden of Tuberculosis (TB) and multidrug-resistant TB (MDR-TB) worldwide. Innovative technology is the need of the hour to identify these cases that remain either undiagnosed or inadequately diagnosed due to the unavailability of appropriate tools at primary healthcare settings. We developed and evaluated 3 kits, namely ‘TB Detect’ (containing BioFM-Filter device), ‘TB Concentration and Transport’ (containing Trans-Filter device) and ‘TB DNA Extraction’ kits. These kits enable bio-safe equipment-free concentration of sputum on filters and improved fluorescence microscopy at primary healthcare centres, ambient temperature transport of dried inactivated sputum filters to central laboratories and molecular detection of drug resistance by PCR and DNA sequencing (Mol-DST). In a 2-site evaluation (n = 1190 sputum specimens) on presumptive TB patients, BioFM-Filter smear exhibited a significant increase in positivity of 7% and 4% over ZN smear and LED-FM smear (p<0.05), respectively and an increment in smear grade status (1+ or 2+ to 3+) of 16% over ZN smear and 20% over LED-FM smear. The sensitivity of Mol-DST in presumptive MDR-TB and XDR-TB cases (n = 148) was 90% for Rifampicin (95% confidence interval [CI], 78–96%), 84% for Isoniazid (95% CI, 72–92%), 83% for Fluoroquinolones (95% CI, 66–93%) and 75% for Aminoglycosides (95% CI, 35–97%), using phenotypic DST as the reference standard. Test specificity was 88–93% and concordance was ~89–92% (κ value 0.8–0.9). The patient-friendly kits described here address several of the existing challenges and are designed to provide ‘Universal Access’ to rapid TB diagnosis, including drug-resistant disease. Their utility was demonstrated by application to sputum at 2 sites in India. Our findings pave the way for larger studies in different point-of-care settings, including high-density urban areas and remote geographical locations.

Structural switching electrochemical DNA aptasensor for the rapid diagnosis of tuberculous meningitis

Background

Tuberculous meningitis (TBM) is the most devastating manifestation of extra-pulmonary tuberculosis. About 33% of TBM patients die due to very late diagnosis of the disease. Conventional diagnostic methods based on signs and symptoms, cerebrospinal fluid (CSF) smear microscopy or liquid culture suffer from either poor sensitivity or long turnaround time (up to 8 weeks). Therefore, in order to manage the disease efficiently, there is an urgent and unmet need for a rapid and reliable diagnostic test.

Methods

In the current study, to address the diagnostic challenge of TBM, a highly rapid and sensitive structural switching electrochemical aptasensor was developed by combining the electrochemical property of methylene blue (MB) with the molecular recognition ability of a ssDNA aptamer. To demonstrate the clinical diagnostic utility of the developed aptasensor, a blinded study was performed on 81 archived CSF specimens using differential pulse voltammetry.

Results

The electrochemical aptasensor developed in the current study can detect as low as 10 pg HspX in CSF background and yields a highly discriminatory response (P<0.0001) for TBM and not-TBM categories with ~95% sensitivity and ~97.5% specificity and has the ability to deliver sample-to-answer in ≤30 minutes.

Conclusion

In summary, we demonstrate a new aptamer-based electrochemical biosensing strategy by exploiting the target-induced structural switching of H63 SL-2 M6 aptamer and electroactivity of aptamer-tagged MB for the detection of HspX in CSF samples for the diagnosis of TBM. Further, the clinical utility of this sensor could be extended for the diagnosis of other forms of tuberculosis in the near future.

A novel aptamer-based test for the rapid and accurate diagnosis of pleural tuberculosis

Pleural tuberculosis (pTB) is diagnosed by using a composite reference standard (CRS) since microbiological methods are grossly inadequate and an accurate diagnostic test remains an unmet need. The present study aimed to evaluate the utility of Mycobacterium tuberculosis (Mtb) antigen and DNA-based tests for pTB diagnosis. Patients were classified as 'Definite TB', 'Probable TB' and 'Non-TB' disease according to the CRS. We assessed the performance of in-house antigen detection assays, namely antibody-based Enzyme-Linked ImmunoSorbent Assay (ELISA) and aptamer-based Aptamer-Linked Immobilized Sorbent Assay (ALISA), targeting Mtb HspX protein and DNA-based tests namely, Xpert MTB/RIF and in-house devR-qPCR. ROC curves were generated for the combined group of 'Definite TB' and 'Probable TB' vs. 'Non-TB' disease group and cut-off values were derived to provide specificity of ≥98%. The sensitivity of ALISA was ∼93% vs. ∼24% of ELISA (p-value ≤0.0001). devR-qPCR exhibited a sensitivity of 50% vs. ∼22% of Xpert (p-value ≤0.01). This novel aptamer-based ALISA test surpasses the sensitivity criterion and matches the specificity requirement spelt out in the 'Target product profile' for extrapulmonary tuberculosis samples by Unitaid (Sensitivity ≥80%, Specificity 98%). The superior performance of the aptamer-based ALISA test indicates its translational potential to bridge the existing gap in pTB diagnosis.

Factors associated with sputum culture conversion in multidrug-resistant pulmonary tuberculosis

INTRODUCTION

Sputum culture conversion in pulmonary multidrug-resistant tuberculosis (MDR-TB) is important to make treatment-related decisions and prevent transmission of disease.

OBJECTIVE

To identify factors associated with sputum culture conversion, and to determine time to culture conversion and the impact of culture conversion on successful treatment outcomes in MDR-/rifampicin (RMP) resistant TB.

METHOD

Retrospective analysis of data from treatment cards and registers of MDR-/RMP-resistant patients initiated on treatment under India's Revised National TB Control Programme in Delhi, West Bengal and Kerala from January 2009 to December 2011. Proportions were calculated and logistic regression analysis was performed.

RESULTS

Of 836 patients, 787 were analysed, 651 (83%) of whom experienced culture conversion: respectively 57%, 73% and 79% culture converted by month 3, 4 and 6 of treatment. The median time to culture conversion was 91.3 days. Patients with body mass index (BMI) 16 kg/m2 (OR 0.403, P = 0.001) and 1618 kg/m2 (OR 0.519, P = 0.039) were less likely to have culture conversion. High rates of culture conversion were observed in patients with successful treatment outcomes compared to those without treatment success (462/469, 99% vs. 183/311, 59%; P 0.0001).

CONCLUSION

Low BMI is associated with poor sputum culture conversion in MDR-/RMP-resistant TB patients. Lack of culture conversion can impact successful treatment outcomes.