Delamanid for multidrug-resistant pulmonary tuberculosis

BACKGROUND

Delamanid (OPC-67683), a nitro-dihydro-imidazooxazole derivative, is a new antituberculosis medication that inhibits mycolic acid synthesis and has shown potent in vitro and in vivo activity against drug-resistant strains of Mycobacterium tuberculosis.

METHODS

In this randomized, placebo-controlled, multinational clinical trial, we assigned 481 patients (nearly all of whom were negative for the human immunodeficiency virus) with pulmonary multidrug-resistant tuberculosis to receive delamanid, at a dose of 100 mg twice daily (161 patients) or 200 mg twice daily (160 patients), or placebo (160 patients) for 2 months in combination with a background drug regimen developed according to World Health Organization guidelines. Sputum cultures were assessed weekly with the use of both liquid broth and solid medium; sputum-culture conversion was defined as a series of five or more consecutive cultures that were negative for growth of M. tuberculosis. The primary efficacy end point was the proportion of patients with sputum-culture conversion in liquid broth medium at 2 months.

RESULTS

Among patients who received a background drug regimen plus 100 mg of delamanid twice daily, 45.4% had sputum-culture conversion in liquid broth at 2 months, as compared with 29.6% of patients who received a background drug regimen plus placebo (P=0.008). Likewise, as compared with the placebo group, the group that received the background drug regimen plus 200 mg of delamanid twice daily had a higher proportion of patients with sputum-culture conversion (41.9%, P=0.04). The findings were similar with assessment of sputum-culture conversion in solid medium. Most adverse events were mild to moderate in severity and were evenly distributed across groups. Although no clinical events due to QT prolongation on electrocardiography were observed, QT prolongation was reported significantly more frequently in the groups that received delamanid.

CONCLUSIONS

Delamanid was associated with an increase in sputum-culture conversion at 2 months among patients with multidrug-resistant tuberculosis. This finding suggests that delamanid could enhance treatment options for multidrug-resistant tuberculosis. (Funded by Otsuka Pharmaceutical Development and Commercialization; ClinicalTrials.gov number, NCT00685360.).

Treatment correlates of successful outcomes in pulmonary multidrug-resistant tuberculosis: an individual patient data meta-analysis

BACKGROUND

Treatment outcomes for multidrug-resistant tuberculosis remain poor. We aimed to estimate the association of treatment success and death with the use of individual drugs, and the optimal number and duration of treatment with those drugs in patients with multidrug-resistant tuberculosis.

METHODS

In this individual patient data meta-analysis, we searched MEDLINE, Embase, and the Cochrane Library to identify potentially eligible observational and experimental studies published between Jan 1, 2009, and April 30, 2016. We also searched reference lists from all systematic reviews of treatment of multidrug-resistant tuberculosis published since 2009. To be eligible, studies had to report original results, with end of treatment outcomes (treatment completion [success], failure, or relapse) in cohorts of at least 25 adults (aged >18 years). We used anonymised individual patient data from eligible studies, provided by study investigators, regarding clinical characteristics, treatment, and outcomes. Using propensity score-matched generalised mixed effects logistic, or linear regression, we calculated adjusted odds ratios and adjusted risk differences for success or death during treatment, for specific drugs currently used to treat multidrug-resistant tuberculosis, as well as the number of drugs used and treatment duration.

FINDINGS

Of 12 030 patients from 25 countries in 50 studies, 7346 (61%) had treatment success, 1017 (8%) had failure or relapse, and 1729 (14%) died. Compared with failure or relapse, treatment success was positively associated with the use of linezolid (adjusted risk difference 0·15, 95% CI 0·11 to 0·18), levofloxacin (0·15, 0·13 to 0·18), carbapenems (0·14, 0·06 to 0·21), moxifloxacin (0·11, 0·08 to 0·14), bedaquiline (0·10, 0·05 to 0·14), and clofazimine (0·06, 0·01 to 0·10). There was a significant association between reduced mortality and use of linezolid (-0·20, -0·23 to -0·16), levofloxacin (-0·06, -0·09 to -0·04), moxifloxacin (-0·07, -0·10 to -0·04), or bedaquiline (-0·14, -0·19 to -0·10). Compared with regimens without any injectable drug, amikacin provided modest benefits, but kanamycin and capreomycin were associated with worse outcomes. The remaining drugs were associated with slight or no improvements in outcomes. Treatment outcomes were significantly worse for most drugs if they were used despite in-vitro resistance. The optimal number of effective drugs seemed to be five in the initial phase, and four in the continuation phase. In these adjusted analyses, heterogeneity, based on a simulated I² method, was high for approximately half the estimates for specific drugs, although relatively low for number of drugs and durations analyses.

INTERPRETATION

Although inferences are limited by the observational nature of these data, treatment outcomes were significantly better with use of linezolid, later generation fluoroquinolones, bedaquiline, clofazimine, and carbapenems for treatment of multidrug-resistant tuberculosis. These findings emphasise the need for trials to ascertain the optimal combination and duration of these drugs for treatment of this condition.

FUNDING

American Thoracic Society, Canadian Institutes of Health Research, US Centers for Disease Control and Prevention, European Respiratory Society, Infectious Diseases Society of America.

Rapid diagnosis of tuberculosis with the Xpert MTB/RIF assay in high burden countries: a cost-effectiveness analysis

BACKGROUND

Xpert MTB/RIF (Xpert) is a promising new rapid diagnostic technology for tuberculosis (TB) that has characteristics that suggest large-scale roll-out. However, because the test is expensive, there are concerns among TB program managers and policy makers regarding its affordability for low- and middle-income settings.

METHODS AND FINDINGS

We estimate the impact of the introduction of Xpert on the costs and cost-effectiveness of TB care using decision analytic modelling, comparing the introduction of Xpert to a base case of smear microscopy and clinical diagnosis in India, South Africa, and Uganda. The introduction of Xpert increases TB case finding in all three settings; from 72%-85% to 95%-99% of the cohort of individuals with suspected TB, compared to the base case. Diagnostic costs (including the costs of testing all individuals with suspected TB) also increase: from US$28-US$49 to US$133-US$146 and US$137-US$151 per TB case detected when Xpert is used "in addition to" and "as a replacement of" smear microscopy, respectively. The incremental cost effectiveness ratios (ICERs) for using Xpert "in addition to" smear microscopy, compared to the base case, range from US$41-$110 per disability adjusted life year (DALY) averted. Likewise the ICERS for using Xpert "as a replacement of" smear microscopy range from US$52-$138 per DALY averted. These ICERs are below the World Health Organization (WHO) willingness to pay threshold.

CONCLUSIONS

Our results suggest that Xpert is a cost-effective method of TB diagnosis, compared to a base case of smear microscopy and clinical diagnosis of smear-negative TB in low- and middle-income settings where, with its ability to substantially increase case finding, it has important potential for improving TB diagnosis and control. The extent of cost-effectiveness gain to TB programmes from deploying Xpert is primarily dependent on current TB diagnostic practices. Further work is required during scale-up to validate these findings.

Estimating the future burden of multidrug-resistant and extensively drug-resistant tuberculosis in India, the Philippines, Russia, and South Africa: a mathematical modelling study

BACKGROUND

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis are emerging worldwide. The Green Light Committee initiative supported programmatic management of drug-resistant tuberculosis in 90 countries. We used estimates from the Preserving Effective TB Treatment Study to predict MDR and XDR tuberculosis trends in four countries with a high burden of MDR tuberculosis: India, the Philippines, Russia, and South Africa.

METHODS

We calibrated a compartmental model to data from drug resistance surveys and WHO tuberculosis reports to forecast estimates of incident MDR and XDR tuberculosis and the percentage of incident MDR and XDR tuberculosis caused by acquired drug resistance, assuming no fitness cost of resistance from 2000 to 2040 in India, the Philippines, Russia, and South Africa.

FINDINGS

The model forecasted the percentage of MDR tuberculosis among incident cases of tuberculosis to increase, reaching 12·4% (95% prediction interval 9·4-16·2) in India, 8·9% (4·5-11·7) in the Philippines, 32·5% (27·0-35·8) in Russia, and 5·7% (3·0-7·6) in South Africa in 2040. It also predicted the percentage of XDR tuberculosis among incident MDR tuberculosis to increase, reaching 8·9% (95% prediction interval 5·1-12·9) in India, 9·0% (4·0-14·7) in the Philippines, 9·0% (4·8-14·2) in Russia, and 8·5% (2·5-14·7) in South Africa in 2040. Acquired drug resistance would cause less than 30% of incident MDR tuberculosis during 2000-40. Acquired drug resistance caused 80% of incident XDR tuberculosis in 2000, but this estimate would decrease to less than 50% by 2040.

INTERPRETATION

MDR and XDR tuberculosis were forecast to increase in all four countries despite improvements in acquired drug resistance shown by the Green Light Committee-supported programmatic management of drug-resistant tuberculosis. Additional control efforts beyond improving acquired drug resistance rates are needed to stop the spread of MDR and XDR tuberculosis in countries with a high burden of MDR tuberculosis.

FUNDING

US Agency for International Development and US Centers for Disease Control and Prevention, Division of Tuberculosis Elimination.

Predicting extensively drug-resistant Mycobacterium tuberculosis phenotypes with genetic mutations

Molecular diagnostic methods based on the detection of mutations conferring drug resistance are promising technologies for rapidly detecting multidrug-/extensively drug-resistant tuberculosis (M/XDR TB), but large studies of mutations as markers of resistance are rare. The Global Consortium for Drug-Resistant TB Diagnostics analyzed 417 Mycobacterium tuberculosis isolates from multinational sites with a high prevalence of drug resistance to determine the sensitivities and specificities of mutations associated with M/XDR TB to inform the development of rapid diagnostic methods. We collected M/XDR TB isolates from regions of high TB burden in India, Moldova, the Philippines, and South Africa. The isolates underwent standardized phenotypic drug susceptibility testing (DST) to isoniazid (INH), rifampin (RIF), moxifloxacin (MOX), ofloxacin (OFX), amikacin (AMK), kanamycin (KAN), and capreomycin (CAP) using MGIT 960 and WHO-recommended critical concentrations. Eight genes (katG, inhA, rpoB, gyrA, gyrB, rrs, eis, and tlyA) were sequenced using Sanger sequencing. Three hundred seventy isolates were INHr, 356 were RIFr, 292 were MOXr/OFXr, 230 were AMKr, 219 were CAPr, and 286 were KANr. Four single nucleotide polymorphisms (SNPs) in katG/inhA had a combined sensitivity of 96% and specificities of 97 to 100% for the detection of INHr. Eleven SNPs in rpoB had a combined sensitivity of 98% for RIFr. Eight SNPs in gyrA codons 88 to 94 had sensitivities of 90% for MOXr/OFXr. The rrs 1401/1484 SNPs had 89 to 90% sensitivity for detecting AMKr/CAPr but 71% sensitivity for KANr. Adding eis promoter SNPs increased the sensitivity to 93% for detecting AMKr and to 91% for detecting KANr. Approximately 30 SNPs in six genes predicted clinically relevant XDR-TB phenotypes with 90 to 98% sensitivity and almost 100% specificity.

Efficacy, safety, and immunogenicity of a booster regimen of Ad26.COV2.S vaccine against COVID-19 (ENSEMBLE2): results of a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Despite the availability of effective vaccines against COVID-19, booster vaccinations are needed to maintain vaccine-induced protection against variant strains and breakthrough infections. This study aimed to investigate the efficacy, safety, and immunogenicity of the Ad26.COV2.S vaccine (Janssen) as primary vaccination plus a booster dose.

METHODS

ENSEMBLE2 is a randomised, double-blind, placebo-controlled, phase 3 trial including crossover vaccination after emergency authorisation of COVID-19 vaccines. Adults aged at least 18 years without previous COVID-19 vaccination at public and private medical practices and hospitals in Belgium, Brazil, Colombia, France, Germany, the Philippines, South Africa, Spain, the UK, and the USA were randomly assigned 1:1 via a computer algorithm to receive intramuscularly administered Ad26.COV2.S as a primary dose plus a booster dose at 2 months or two placebo injections 2 months apart. The primary endpoint was vaccine efficacy against the first occurrence of molecularly confirmed moderate to severe-critical COVID-19 with onset at least 14 days after booster vaccination, which was assessed in participants who received two doses of vaccine or placebo, were negative for SARS-CoV-2 by PCR at baseline and on serology at baseline and day 71, had no major protocol deviations, and were at risk of COVID-19 (ie, had no PCR-positive result or discontinued the study before day 71). Safety was assessed in all participants; reactogenicity, in terms of solicited local and systemic adverse events, was assessed as a secondary endpoint in a safety subset (approximately 6000 randomly selected participants). The trial is registered with ClinicalTrials.gov, NCT04614948, and is ongoing.

FINDINGS

Enrolment began on Nov 16, 2020, and the primary analysis data cutoff was June 25, 2021. From 34 571 participants screened, the double-blind phase enrolled 31 300 participants, 14 492 of whom received two doses (7484 in the Ad26.COV2.S group and 7008 in the placebo group) and 11 639 of whom were eligible for inclusion in the assessment of the primary endpoint (6024 in the Ad26.COV2.S group and 5615 in the placebo group). The median (IQR) follow-up post-booster vaccination was 36·0 (15·0-62·0) days. Vaccine efficacy was 75·2% (adjusted 95% CI 54·6-87·3) against moderate to severe-critical COVID-19 (14 cases in the Ad26.COV2.S group and 52 cases in the placebo group). Most cases were due to the variants alpha (B.1.1.7) and mu (B.1.621); endpoints for the primary analysis accrued from Nov 16, 2020, to June 25, 2021, before the global dominance of delta (B.1.617.2) or omicron (B.1.1.529). The booster vaccine exhibited an acceptable safety profile. The overall frequencies of solicited local and systemic adverse events (evaluated in the safety subset, n=6067) were higher among vaccine recipients than placebo recipients after the primary and booster doses. The frequency of solicited adverse events in the Ad26.COV2.S group were similar following the primary and booster vaccinations (local adverse events, 1676 [55·6%] of 3015 vs 896 [57·5%] of 1559, respectively; systemic adverse events, 1764 [58·5%] of 3015 vs 821 [52·7%] of 1559, respectively). Solicited adverse events were transient and mostly grade 1-2 in severity.

INTERPRETATION

A homologous Ad26.COV2.S booster administered 2 months after primary single-dose vaccination in adults had an acceptable safety profile and was efficacious against moderate to severe-critical COVID-19. Studies assessing efficacy against newer variants and with longer follow-up are needed.

FUNDING

Janssen Research & Development.

Lipoarabinomannan in sputum to detect bacterial load and treatment response in patients with pulmonary tuberculosis: Analytic validation and evaluation in two cohorts

BACKGROUND

Lipoarabinomannan (LAM) is a major antigen of Mycobacterium tuberculosis (MTB). In this report, we evaluated the ability of a novel immunoassay to measure concentrations of LAM in sputum as a biomarker of bacterial load prior to and during treatment in pulmonary tuberculosis (TB) patients.

METHODS AND FINDINGS

Phage display technology was used to isolate monoclonal antibodies binding to epitopes unique in LAM from MTB and slow-growing nontuberculous mycobacteria (NTM). Using these antibodies, a sandwich enzyme-linked immunosorbent assay (LAM-ELISA) was developed to quantitate LAM concentration. The LAM-ELISA had a lower limit of quantification of 15 pg/mL LAM, corresponding to 121 colony-forming units (CFUs)/mL of MTB strain H37Rv. It detected slow-growing NTMs but without cross-reacting to common oral bacteria. Two clinical studies were performed between the years 2013 and 2016 in Manila, Philippines, in patients without known human immunodeficiency virus (HIV) coinfection. In a case-control cohort diagnostic study, sputum specimens were collected from 308 patients (aged 17-69 years; 62% male) diagnosed as having pulmonary TB diseases or non-TB diseases, but who could expectorate sputum, and were then evaluated by smear microscopy, BACTEC MGIT 960 Mycobacterial Detection System (MGIT) and Lowenstein-Jensen (LJ) culture, and LAM-ELISA. Some sputum specimens were also examined by Xpert MTB/RIF. The LAM-ELISA detected all smear- and MTB-culture-positive samples (n = 70) and 50% (n = 29) of smear-negative but culture-positive samples (n = 58) (versus 79.3%; 46 positive cases by the Xpert MTB/RIF), but none from non-TB patients (n = 56). Among both LAM and MGIT MTB-culture-positive samples, log10-transformed LAM concentration and MGIT time to detection (TTD) showed a good inverse relationship (r = -0.803, p < 0.0001). In a prospective longitudinal cohort study, 40 drug-susceptible pulmonary TB patients (aged 18-69 years; 60% male) were enrolled during the first 56 days of the standard 4-drug therapy. Declines in sputum LAM concentrations correlated with increases of MGIT TTD in individual patients. There was a 1.29 log10 decrease of sputum LAM concentration, corresponding to an increase of 221 hours for MGIT TTD during the first 14 days of treatment, a treatment duration often used in early bactericidal activity (EBA) trials. Major limitations of this study include a relatively small number of patients, treatment duration up to only 56 days, lack of quantitative sputum culture CFU count data, and no examination of the correlation of sputum LAM to clinical cure.

CONCLUSIONS

These results indicate that the LAM-ELISA can determine LAM concentration in sputum, and sputum LAM measured by the assay may be used as a biomarker of bacterial load prior to and during TB treatment. Additional studies are needed to examine the predictive value of this novel biomarker on treatment outcomes.

Evaluation of pyrosequencing for detecting extensively drug-resistant Mycobacterium tuberculosis among clinical isolates from four high-burden countries

Reliable molecular diagnostics, which detect specific mutations associated with drug resistance, are promising technologies for the rapid identification and monitoring of drug resistance in Mycobacterium tuberculosis isolates. Pyrosequencing (PSQ) has the ability to detect mutations associated with first- and second-line anti-tuberculosis (TB) drugs, with the additional advantage of being rapidly adaptable for the identification of new mutations. The aim of this project was to evaluate the performance of PSQ in predicting phenotypic drug resistance in multidrug- and extensively drug-resistant tuberculosis (M/XDR-TB) clinical isolates from India, South Africa, Moldova, and the Philippines. A total of 187 archived isolates were run through a PSQ assay in order to identify M. tuberculosis (via the IS6110 marker), and to detect mutations associated with M/XDR-TB within small stretches of nucleotides in selected loci. The molecular targets included katG, the inhA promoter and the ahpC-oxyR intergenic region for isoniazid (INH) resistance; the rpoB core region for rifampin (RIF) resistance; gyrA for fluoroquinolone (FQ) resistance; and rrs for amikacin (AMK), capreomycin (CAP), and kanamycin (KAN) resistance. PSQ data were compared to phenotypic mycobacterial growth indicator tube (MGIT) 960 drug susceptibility testing results for performance analysis. The PSQ assay illustrated good sensitivity for the detection of resistance to INH (94%), RIF (96%), FQ (93%), AMK (84%), CAP (88%), and KAN (68%). The specificities of the assay were 96% for INH, 100% for RIF, FQ, AMK, and KAN, and 97% for CAP. PSQ is a highly efficient diagnostic tool that reveals specific nucleotide changes associated with resistance to the first- and second-line anti-TB drug medications. This methodology has the potential to be linked to mutation-specific clinical interpretation algorithms for rapid treatment decisions.

Delamanid Central Nervous System Pharmacokinetics in Tuberculous Meningitis in Rabbits and Humans

Central nervous system tuberculosis (TB) is devastating and affects vulnerable populations. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculous meningitis (TBM) specifically are nearly uniformly fatal, with little information being available to guide the treatment of these patients. Delamanid (DLM), a nitro-dihydro-imidazooxazole, is a new, well-tolerated anti-TB drug with a low MIC (1 to 12 ng/ml) against Mycobacterium tuberculosis It is used for the treatment of pulmonary MDR-TB, but pharmacokinetic (PK) data for DLM in the central nervous system (CNS) of patients with TBM are not available. In the present study, we measured DLM concentrations in the brain and cerebrospinal fluid (CSF) of six rabbits with and without experimentally induced TBM receiving single-dose DLM. We report the steady-state CSF concentrations from three patients receiving DLM as part of multidrug treatment who underwent therapeutic drug monitoring. Drug was quantified using liquid chromatography-tandem mass spectrometry. In rabbits and humans, mean concentrations in CSF (in rabbits, 1.26 ng/ml at 9 h and 0.47 ng/ml at 24 h; in humans, 48 ng/ml at 4 h) were significantly lower than those in plasma (in rabbits, 124 ng/ml at 9 h and 14.5 ng/ml at 24 h; in humans, 726 ng/ml at 4 h), but the estimated free CSF/plasma ratios were generally >1. In rabbits, DLM concentrations in the brain were 5-fold higher than those in plasma (means, 518 ng/ml at 9 h and 74.0 ng/ml at 24 h). All patients with XDR-TBM receiving DLM experienced clinical improvement and survival. Collectively, these results suggest that DLM achieves adequate concentrations in brain tissue. Despite relatively low total CSF drug levels, free drug may be sufficient and DLM may have a role in treating TBM. More studies are needed to develop a fuller understanding of its distribution over time with treatment and clinical effectiveness.

Impact of patient and program factors on default during treatment of multidrug-resistant tuberculosis

SETTING

In the Philippines, programmatic treatment of drug-resistant tuberculosis (TB) was initiated by the Tropical Disease Foundation in 1999 and transitioned to the National TB Program in 2006.

OBJECTIVE

To determine patient and socio-demographic characteristics associated with default, and the impact of patient support measures on default.

DESIGN

Retrospective cohort analysis of 583 MDR-TB patients treated from 1999 to 2006.

RESULTS

A total of 88 (15%) patients defaulted from treatment. The median follow-up time for patients who defaulted was 289 days (range 1-846). In multivariate analysis adjusted for age, sex and previous TB treatment, receiving a greater number of treatment drugs (≥ 5 vs. 2-3 drugs, HR 7.2, 95%CI 3.3-16.0, P < 0.001) was significantly associated with an increased risk of default, while decentralization reduced the risk of default (HR 0.3, 95%CI 0.2-0.7, P < 0.001).

CONCLUSION

Improving access to treatment for MDR-TB through decentralization of care to centers near the patient's residence reduced the risk of default. Further research is needed to evaluate the feasibility, impact and cost-effectiveness of decentralized care models for MDR-TB treatment.

Predicting differential rifamycin resistance in clinical Mycobacterium tuberculosis isolates by specific rpoB mutations

SETTING

Rifampin (RMP) resistant Mycobacterium tuberculosis is usually assumed to be resistant to all rifamycins. Increasing evidence indicates, however, that some rpoB mutations, detectable by rapid molecular diagnostics, confer resistance to RMP but not to rifabutin (RBT), suggesting that RBT may be effective for the treatment of M. tuberculosis with these mutations.

OBJECTIVE

To determine if specific rpoB mutations reliably predict differential phenotypic resistance to RMP and RBT.

DESIGN

We selected 60 clinical M. tuberculosis isolates from a repository of multinational multidrug-resistant tuberculosis isolates and stratified them into two groups: 1) those with rpoB mutations suspected to confer differential resistance to RMP and RBT, and 2) those expected to be cross-resistant to RMP and RBT. These assumptions were tested by comparing the phenotypic susceptibilities of RMP/RBT with those predicted by mutations in the rpoB gene.

RESULTS

Of 20 suspected RMP-resistant/RBT-susceptible isolates, 15 were RMP-resistant but RBT-susceptible, 3 were RMP- and RBT-susceptible, and 2 were cross-resistant to both RMP and RBT. In comparison, 40 of 40 suspected cross-resistant isolates were both RMP- and RBT-resistant.

CONCLUSION

Our data support the association between specific rpoB mutations and differential resistance of M. tuberculosis to RMP and RBT. Clinical studies are required to investigate the efficacy of RBT in the treatment of M. tuberculosis harboring these mutations.

Multidrug-resistant tuberculosis among previously treated patients in the Philippines

SETTING

Prior treatment has been associated with multidrug-resistant tuberculosis (MDR-TB) in many settings. The Philippines ranks fifth among 27 priority countries for MDR-TB.

OBJECTIVE

To determine the rate of MDR-TB among previously treated patients referred for MDR screening and management.

DESIGN

Descriptive study of the rate of MDR-TB among 4705 previously treated patients screened from 2003 to 2008.

RESULTS

MDR-TB was present in 76% of 2438 screened patients who had positive cultures. The proportion of patients with MDR-TB was the same among patients referred from public or DOTS facilities and private or non-DOTS facilities. MDR-TB occurred most frequently among patients who failed treatment with the Category 2 regimen (97%), those who did not demonstrate culture conversion after 3 months of Category 2 treatment (91%), and Category 1 failures (83%). MDR-TB rates were respectively 78% and 57% for Category 2 relapse and return after default (RAD), and respectively 33% and 22% for Category 1 relapse and RAD.

CONCLUSION

MDR-TB is frequent among previously treated patients in the Philippines. Screening with culture and drug susceptibility testing should be considered for these patients.

Implementation of a multidisciplinary antimicrobial stewardship programme in a Philippine tertiary care hospital: an evaluation by repeated point prevalence surveys

OBJECTIVES

Optimising antimicrobial prescribing in hospitals through antimicrobial stewardship (AMS) is essential in addressing the global threat of antimicrobial resistance. The objective of this study was to evaluate the impact of a hospital-wide programme, delivered by a multidisciplinary AMS team, on antimicrobial prescribing outcomes.

METHODS

The AMS programme consisted of a combination of persuasive, restrictive, and structural components and was implemented in two phases. We used data from the Global-PPS, collected every six months between September 2017 and December 2019, to measure the antimicrobial use prevalence and monitor selected antibiotic prescribing quality indicators.

RESULTS

A significantly increasing trend (P < 0.001) was observed for the indicators related to documentation of prescribing, that is the reason for treatment and stop or review date. We observed a significantly decreasing trend (P < 0.001) in the number of prescriptions for surgical antibiotic prophylaxis (SAP) prescribed for more than 24 h; however, sample sizes for surgical patients were small. For these three indicators, a sudden and pronounced improvement was seen after the second set of interventions, which consisted of (i) an antibiotic documentation policy, (ii) a 24-h automatic stop order for SAP, and (iii) dissemination of new SAP guidelines. A significantly decreasing trend was also observed for hospital-wide antimicrobial use prevalence (P < 0.001).

CONCLUSIONS

The implementation of a multidisciplinary antimicrobial stewardship programme positively influenced antibiotic prescribing practices. Further research should address long-term trends in antibiotic prescribing to establish whether these coordinated activities have led to a sustained behaviour change among prescribers, thereby also evaluating clinical outcomes and antimicrobial resistance rates.

Prognostic significance of novel katG mutations in Mycobacterium tuberculosis

BACKGROUND

By using whole genome sequencing (WGS), researchers are beginning to understand the genetic diversity of Mycobacterium tuberculosis (MTB) and its consequences for the diagnosis of multidrug-resistant tuberculosis (MDR-TB) on a genomic scale. The Global Consortium for Drug-resistant TB Diagnostics (GCDD) conducted a genome scale variant analyses of 366 clinical MTB genomes (mostly MDR/XDR [extensively drug resistant]) from four countries in order to inform the development of rapid molecular diagnostics. This project has been extended by performing an evolutionary analysis of isoniazid (INH)-resistant isolates for prognostic purposes.

METHODS

151 (130 INH^R, 21 INH^S) clinical MTB isolates from India (19: 17 INH^R, 2 INH^S), Moldova (48: 42 INH^R, 6 INH^S), the Philippines (26: 20 INH^R, 6 INH^S), and South Africa (58: 51 INH^R, 7 INH^S) were included in this study. INH drug susceptibility was determined by using MGIT 960 and WHO (World Health Organization)-recommended critical concentration of 0.1 mg/L. Isolates were sequenced using PacBio RS WGS platform. A genome-wide variant analysis was conducted using a proprietary pipeline (PacDAP) developed at San Diego State University. To infer the amino acid changes in katG that confer resistance, PAML was utilized to detect sites in silico that are under positive selection. The dN/dS method was used in combination with Bayes empirical Bayes to determine sites under positive selection and Chi-Squared analysis to determine the significance of the selected sites.

RESULTS

PacDAP variant analysis revealed 22 novel catalase-peroxidase (katG product) mutations. Of these, 14 were single nucleotide polymorphisms, while 8 novel mutations appeared in combination with katG S315T and/or with inhA promoter C-15T. These SNPs have not been previously reported. Additionally, 11 previously observed, but uncommon, katG mutations were also observed in these clinical isolates. These results suggest that 17 amino acids in the enzyme are under positive selective pressure; most significantly in South Africa and the Philippines. No selective pressure on codons other than 315 was observed in isolates from Moldova. Due to the low number of isolates from India, the significance of the sites under positive selection was low and no prediction for India could be made based on this study.

CONCLUSIONS

Eleven of the 14 SNPs are resistance conferring, and it is believed that the remaining 8 combinatorial mutations are either compensatory in nature or, in combination with known SNPs, could increase resistance levels. Positive selection results indicate a diversifying evolutionary path to resistance more in line with long tail statistics and therefore indicate a departure from the traditional point mutation (or "hotspot") model that current molecular diagnostics are based on. Positive selection pressures indicate a future with elevated diagnostic and prognostic significance of the "long tail" (i.e., alternative mechanisms of resistance) and potentially diminishing significance of the canonical mutations (especially in South Africa and the Philippines), which could have significant future implications on narrowly targeting molecular diagnostics.

Time Trend Analysis of Tuberculosis Treatment While Using Digital Adherence Technologies-An Individual Patient Data Meta-Analysis of Eleven Projects across Ten High Tuberculosis-Burden Countries

Worldwide, non-adherence to tuberculosis (TB) treatment is problematic. Digital adherence technologies (DATs) offer a person-centered approach to support and monitor treatment. We explored adherence over time while using DATs. We conducted a meta-analysis on anonymized longitudinal adherence data for drug-susceptible (DS) TB (n = 4515) and drug-resistant (DR) TB (n = 473) populations from 11 DAT projects. Using Tobit regression, we assessed adherence for six months of treatment across sex, age, project enrolment phase, DAT-type, health care facility (HCF), and project. We found that DATs recorded high levels of adherence throughout treatment: 80% to 71% of DS-TB patients had ≥90% adherence in month 1 and 6, respectively, and 73% to 75% for DR-TB patients. Adherence increased between month 1 and 2 (DS-TB and DR-TB populations), then decreased (DS-TB). Males displayed lower adherence and steeper decreases than females (DS-TB). DS-TB patients aged 15−34 years compared to those >50 years displayed steeper decreases. Adherence was correlated within HCFs and differed between projects. TB treatment adherence decreased over time and differed between subgroups, suggesting that over time, some patients are at risk for non-adherence. The real-time monitoring of medication adherence using DATs provides opportunities for health care workers to identify patients who need greater levels of adherence support.

Feasibility and acceptability of asynchronous VOT among patients with MDR-TB

BACKGROUND: We conducted a feasibility and acceptability study of video-observed therapy (VOT) among patients with multidrug-resistant TB (MDR-TB) and other types of drug-resistant TB (DR-TB) in the Philippines.METHODS: Patients aged ≥13 years were approached to use VOT. A smartphone with VOT mobile application to video-record medication intake was provided. Healthcare workers (HCWs) monitored adherence by watching videos via a web-based dashboard. Good adherence was defined as intake of >90% of expected doses. Feasibility and acceptability were assessed using a semi-structured questionnaire on a Likert scale.RESULTS: Of 308 patients, 110 (36%) patients chose VOT; 67 completed treatment using VOT and 43 stopped VOT prior to treatment outcome; 74/110 (67%) had good adherence. The treatment success rate was 88% and the loss to follow-up rate was 8.1%. Among HCWs, 90% (9/10) had a positive perception of VOT. All HCWs agreed that VOT data accurately reflect medication intake of the patients; 88/89 (99%) mentioned benefits of VOT, notably convenience, sense of comfort, privacy and security.CONCLUSIONS: VOT is feasible and acceptable for both patients and HCWs. This study could provide guidance to the country programme to launch VOT for treatment of patients with MDR-TB and other DR-TB.

Standards for clinical trials for treating TB

BACKGROUND: The value, speed of completion and robustness of the evidence generated by TB treatment trials could be improved by implementing standards for best practice.METHODS: A global panel of experts participated in a Delphi process, using a 7-point Likert scale to score and revise draft standards until consensus was reached.RESULTS: Eleven standards were defined: Standard 1, high quality data on TB regimens are essential to inform clinical and programmatic management; Standard 2, the research questions addressed by TB trials should be relevant to affected communities, who should be included in all trial stages; Standard 3, trials should make every effort to be as inclusive as possible; Standard 4, the most efficient trial designs should be considered to improve the evidence base as quickly and cost effectively as possible, without compromising quality; Standard 5, trial governance should be in line with accepted good clinical practice; Standard 6, trials should investigate and report strategies that promote optimal engagement in care; Standard 7, where possible, TB trials should include pharmacokinetic and pharmacodynamic components; Standard 8, outcomes should include frequency of disease recurrence and post-treatment sequelae; Standard 9, TB trials should aim to harmonise key outcomes and data structures across studies; Standard 10, TB trials should include biobanking; Standard 11, treatment trials should invest in capacity strengthening of local trial and TB programme staff.CONCLUSION: These standards should improve the efficiency and effectiveness of evidence generation, as well as the translation of research into policy and practice.

Cost and cost-effectiveness of BPaL regimen used in drug-resistant TB treatment in the Philippines

BACKGROUND

In 2022, the WHO announced that the 6-month BPaL/M regimen should be used for drug-resistant TB (DR-TB). We estimate the patient and provider costs of BPaL compared to current standard-of-care treatment in the Philippines.

METHODS

Patients on BPaL under operational research, or 9-11-month standard short oral regimen (SSOR) and 18-21-month standard long oral regimen (SLOR) under programmatic conditions were interviewed using the WHO cross-sectional TB patient cost tool. Provider costs were assessed through a bottom-up and top-down costing analysis.

RESULTS

Total patient costs per treatment episode were lowest with BPaL (USD518.0) and increased with use of SSOR (USD825.8) and SLOR (USD1,023.0). Total provider costs per successful treatment were lowest with BPaL (USD1,994.5) and increased with SSOR (USD3,121.5) and SLOR (USD10,032.4). Compared to SSOR, BPaL treatment was cost-effective at even the lowest willingness to pay threshold. As expected, SLOR was the costliest and least effective regimen.

CONCLUSIONS

Costs incurred by patients on BPaL were 37% (95% CI 22-56) less than SSOR and 50% (95% CI 32-68) less than SLOR, while providers could save 36% (95% CI 21-56) to 80% (95% CI 64-93) per successful treatment, respectively. The study shows that treatment of DR-TB with BPaL was cost-saving for patients and cost-effective for the health system.