Thin-Layer-Agar-Based Direct Phenotypic Drug Susceptibility Testing on Sputum in Eswatini Rapidly Detects Mycobacterium tuberculosis Growth and Rifampicin Resistance Otherwise Missed by WHO-Endorsed Diagnostic Tests.

Xpert MTB/RIF rapidly detects resistance to rifampicin (RR); however, this test misses I491F-RR conferring rpoB mutation, common in southern Africa. In addition, Xpert MTB/RIF does not distinguish between viable and dead Mycobacterium tuberculosis (MTB). We aimed to investigate the ability of thin-layer agar (TLA) direct drug-susceptibility testing (DST) to detect MTB and its drug-resistance profiles in field conditions in Eswatini. Consecutive samples were tested in parallel with Xpert MTB/RIF and TLA for rifampicin (1.0 µg/ml) and ofloxacin (2.0 µg/ml). TLA results were compared at the Reference Laboratory in Antwerp with indirect-DST on Löwenstein-Jensen or 7H11 solid media and additional phenotypic and genotypic testing to resolve discordance. TLA showed a positivity rate for MTB detection of 7.1% versus 10.0% for Xpert MTB/RIF. Of a total of 4,547 samples included in the study, 200 isolates were available for comparison to the composite reference. Within a median of 18.4 days, TLA detected RR with 93.0% sensitivity (95% confidence interval [CI], 77.4 to 98.0) and 99.4% specificity (95% CI, 96.7 to 99.9) versus 62.5% (95% CI, 42.7 to 78.8) and 99.3% (95% CI, 96.2 to 99.9) for Xpert MTB/RIF. Eight isolates, 28.6% of all RR-confirmed isolates, carried the I491F mutation, all detected by TLA. TLA also correctly identified 183 of the 184 ofloxacin-susceptible isolates (99.5% specificity; 95% CI, 97.0 to 99.9). In field conditions, TLA rapidly detects RR, and in this specific setting, it contributed to detection of additional RR patients over Xpert MTB/RIF, mainly but not exclusively due to I491F. TLA also accurately excluded fluoroquinolone resistance.

Fluorescein diacetate and rapid molecular testing for the early identification of rifampicin resistance in Mali.

BACKGROUND: Non-conversion on auramine smear microscopy indicates a lack of treatment response, possibly associated with initial rifampicin-resistant tuberculosis (RR-TB). However, dead bacteria still stain positive and may be detected. Fluorescein diacetate smear microscopy (FDA) shows live mycobacteria only. Therefore, we studied the potential of 2-month (2M) FDA for the identification of initial RR-TB.METHODS: Between 2015 and 2018, we enrolled new smear-positive pulmonary TB patients from five local centres in Bamako, Mali. After baseline screening, sputum samples were collected at 1M, 2M, 5M and 18M. We used rpoB sequencing to identify initial RR-TB.RESULTS: Of 1359 patients enrolled, 1019 (75%) had rpoB sequencing results. Twenty-six (2.6%, 95%CI: 1.7-3.7) had mutations conferring rifampicin resistance. Most frequent rpoB mutations were located at the codons Asp435Val (42.4%) and Ser450Leu (34.7%). Among patients with initial RR-TB, 72.2% were FDA-negative at 2M (P = 0.2). The positive and negative predictive value of 5M FDA for culture-based failure was respectively 20.0% and 94.7%.CONCLUSION: FDA did not identify the majority of patients with initial RR-TB or culture-based failure. As the full spectrum of mutations identified on sequencing was identified using Xpert, our data support its rapid universal implementation in Mali.

First-line tuberculosis treatment with double-dose rifampicin is well tolerated.

OBJECTIVE: To compare the occurrence of unfavourable treatment and safety outcomes of double-dose rifampicin (RMP; 20 mg/kg/d, intervention) with standard dose (10 mg/kg/d, control) in a first-line tuberculosis (TB) treatment regimen for smear-positive TB patients in Bangladesh.DESIGN: This was a randomised clinical trial. The primary efficacy and safety endpoints were the occurrence of an unfavourable treatment outcome (death, failure, relapse or loss to follow-up) and the occurrence of any serious drug-related adverse event (SAE).RESULTS: In primary efficacy analysis, among 343 control and 347 intervention patients, respectively 15.5% and 11.8% had an unfavourable outcome. In safety analysis, among 349 intervention and 352 control patients, respectively 4.3% and 2.6% experienced an SAE. These differences were not significant. There was a significantly lower occurrence of SAEs, explained by a lower occurrence of hepatic toxicity, in a RMP double-dosed but erroneously HZE (isoniazid+pyrazinamide+ethambutol) under-dosed subgroup.CONCLUSIONS: Our findings show that there is no statistically significant difference in terms of efficacy and safety between standard and double-dose RMP. An accidental finding (related to dosage levels of the standard regimen) suggests that high-dose RMP is potentially a lesser cause of hepatotoxicity. Larger trials with more power, or trials with at least a triple-dose might be needed to clearly see the effect of high-dose RMP on unfavourable outcomes.

Reduction of diagnostic and treatment delays reduces rifampicin-resistant tuberculosis mortality in Rwanda.

SETTING: In 2005, in response to the increasing prevalence of rifampicin-resistant tuberculosis (RR-TB) and poor treatment outcomes, Rwanda initiated the programmatic management of RR-TB, including expanded access to systematic rifampicin drug susceptibility testing (DST) and standardised treatment.OBJECTIVE: To describe trends in diagnostic and treatment delays and estimate their effect on RR-TB mortality.DESIGN: Retrospective analysis of individual-level data including 748 (85.4%) of 876 patients diagnosed with RR-TB notified to the World Health Organization between 1 July 2005 and 31 December 2016 in Rwanda. Logistic regression was used to estimate the effect of diagnostic and therapeutic delays on RR-TB mortality.RESULTS: Between 2006 and 2016, the median diagnostic delay significantly decreased from 88 days to 1 day, and the therapeutic delay from 76 days to 3 days. Simultaneously, RR-TB mortality significantly decreased from 30.8% in 2006 to 6.9% in 2016. Total delay in starting multidrug-resistant TB (MDR-TB) treatment of more than 100 days was associated with more than two-fold higher odds for dying. When delays were long, empirical RR-TB treatment initiation was associated with a lower mortality.CONCLUSION: The reduction of diagnostic and treatment delays reduced RR-TB mortality. We anticipate that universal testing for RR-TB, short diagnostic and therapeutic delays and effective standardised MDR-TB treatment will further decrease RR-TB mortality in Rwanda.

Gatifloxacin is superior to levofloxacin and moxifloxacin in shorter treatment regimens for multidrug-resistant TB.

SETTING: Data were collected from patients starting one of the shorter treatment regimens (STRs) for multidrug-resistant tuberculosis (MDR-TB) in Bangladesh, Niger or Cameroon.OBJECTIVE: To estimate the effect of either a gatifloxacin (GFX), moxifloxacin (MFX) or levofloxacin (LVX) based STR on bacteriological effectiveness.DESIGN: Retrospective study of prospectively collected data.RESULTS: Among 1530 patients, bacteriological effectiveness was 96.7% overall. Stratified by treatment with a GFX-, LVX- or MFX-based regimen effectiveness was respectively 97.5%, 95.5% and 94.7%. Compared to those on a GFX-based regimen, the estimated summary odds ratio of having an adverse outcome was more than double (OR 2.05, 95% CI 1.09-3.90) in patients treated with either an LVX-based or MFX-based regimen. After adjusting for initial resistance, patients treated with an LVX-based regimen and MFX-based regimen had respectively a 4.5- and 8.4-fold times larger odds of an adverse bacteriological outcome. None among 859 patients at risk treated with a GFX-based compared to at least 4 of 228 among those on an MFX-based regimen acquired fluoroquinolone resistance.CONCLUSION: GFX-based regimens had superior bacteriological effectiveness than MFX-based or LVX-based regimens. As GFX is currently unavailable in most MDR-TB programs, its reintroduction should be prioritised.

Principles for constructing a tuberculosis treatment regimen: the role and definition of core and companion drugs.

Current World Health Organization guidelines for the formulation of treatment regimens for multidrug-resistant tuberculosis (MDR-TB) pay too little attention to the microbiological activity of anti-tuberculosis drugs. Here, we draw lessons from the pioneering work done on shorter MDR-TB treatment regimens and the current knowledge of the bactericidal and sterilizing properties of the drugs to inform the composition of treatment regimens for MDR-TB. We propose to reserve the term 'core drug' for the one drug in a regimen that contributes most to relapse-free cure. The core drug has both moderate to high bactericidal and sterilizing activity, is given throughout treatment, is well tolerated, and has no cross-resistance with the core drug used in the previous regimen. Currently used core drugs include rifampicin in the first-line 6-month regimen, and fourth-generation fluoroquinolones and bedaquiline in regimens for drug-resistant TB. All other drugs are 'companion drugs', used to avert treatment failure due to acquired drug resistance against the core drug. Some also help further reduce the risk of relapse. Moreover, toxic drugs should be avoided if there is an alternative. A regimen must always include the core drug, plus at least one companion drug with high bactericidal activity, a second bactericidal companion drug, plus two sterilizing companion drugs.

Twenty years of rifampicin resistance surveillance in Bangladesh: periodic vs. continuous monitoring.

OBJECTIVE: To analyse 20 years of tuberculosis (TB) drug resistance surveillance, comparing conventional periodic random drug resistance surveys with continuous monitoring, in Damien Foundation-supported districts of Bangladesh. DESIGN: Retrospective study of data on TB drug resistance from five periodic surveys among newly registered patients vs. continuous monitoring of retreatment patients from 1996 to 2016. RESULTS: Periodic surveys and continuous monitoring showed similar trends in rifampicin (RMP) resistance; with all smear-positives registered as denominator, prevalence in new cases was found to be at approximately the same level as incidence in retreatment cases. Changes in trends observed using continuous monitoring preceded those detected in periodic surveys by a few years. The accurate interpretation of trend changes requires detailed knowledge of changes in treatment regimens, referral criteria, testing methods and operational factors. CONCLUSION: Low rates of resistance to RMP, isoniazid and the fluoroquinolones were maintained over the two decades, indicating excellent TB programme performance, including highly active standard first- and second-line treatment regimens. Continuous monitoring is feasible, but requires rigorous application of referral guidelines and data maintenance. Contrary to random surveys, continuous monitoring provides early indications of programme performance, essential for individual patient management, and is more efficient and cost-effective.

Management of pregnant women infected with Ebola virus in a treatment centre in Guinea, June 2014.

We report two cases of confirmed Ebola virus disease in pregnant women, who presented at the Médecins Sans Frontières Ebola treatment centre in Guéckédou. Despite the very high risk of death, both pregnant women survived. In both cases the critical decision was made to induce vaginal delivery. We raise a number of considerations regarding the management of Ebola virus-infected pregnant women, including the place of amniocentesis and induced delivery, and whether certain invasive medical acts are justified.

Describing readmissions to an Ebola case management centre (CMC), Sierra Leone, 2014.

Case management centres (CMCs) are part of the outbreak control plan for Ebola virus disease (EVD). A CMC in Sierra Leone had 33% (138/419) of primary admissions discharged as EVD negative (not a case). Fifteen of these were readmitted within 21 days, nine of which were EVD positive. All readmissions had contact with an Ebola case in the community in the previous 21 days indicating that the infection was likely acquired outside the CMC.