Outcomes of a nine-month regimen for rifampicin-resistant tuberculosis up to 24 months after treatment completion in nine African countries

Estimating Post-treatment Recurrence After Multidrug-Resistant Tuberculosis Treatment Among Patients With and Without Human Immunodeficiency Virus: The Impact of Assumptions About Death and Missing Follow-up

BACKGROUND

Quantification of recurrence risk following successful treatment is crucial to evaluating regimens for multidrug- or rifampicin-resistant (MDR/RR) tuberculosis (TB). However, such analyses are complicated when some patients die or become lost during post-treatment follow-up.

METHODS

We analyzed data on 1991 patients who successfully completed a longer MDR/RR-TB regimen containing bedaquiline and/or delamanid between 2015 and 2018 in 16 countries. Using 5 approaches for handling post-treatment deaths, we estimated 6-month post-treatment TB recurrence risk overall and by HIV status. We used inverse-probability weighting to account for patients with missing follow-up and investigated the impact of potential bias from excluding these patients without applying inverse-probability weights.

RESULTS

The estimated TB recurrence risk was 7.4/1000 (95% credible interval: 3.3-12.8) when deaths were handled as non-recurrences and 7.6/1000 (3.3-13.0) when deaths were censored and inverse-probability weights were applied to account for the excluded deaths. The estimated risks of composite recurrence outcomes were 25.5 (15.3-38.1), 11.7 (6.4-18.2), and 8.6 (4.1-14.4) per 1000 for recurrence or (1) any death, (2) death with unknown or TB-related cause, or (3) TB-related death, respectively. Corresponding relative risks for HIV status varied in direction and magnitude. Exclusion of patients with missing follow-up without inverse-probability weighting had a small impact on estimates.

CONCLUSIONS

The estimated 6-month TB recurrence risk was low, and the association with HIV status was inconclusive due to few recurrence events. Estimation of post-treatment recurrence will be enhanced by explicit assumptions about deaths and appropriate adjustment for missing follow-up data.

Molecular mechanisms of resistance and treatment efficacy of clofazimine and bedaquiline against Mycobacterium tuberculosis

Clofazimine (CFZ) and bedaquiline (BDQ) are currently used for the treatment of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) strains. In recent years, adding CFZ and BDQ to tuberculosis (TB) drug regimens against MDR Mtb strains has significantly improved treatment results, but these improvements are threatened by the emergence of MDR and extensively drug-resistant (XDR) Mtb strains. Recently, CFZ and BDQ have attracted much attention for their strong clinical efficacy, although very little is known about the mechanisms of action, drug susceptibility test (DST), resistance mechanisms, cross-resistance, and pharmacokinetics of these two drugs. In this current review, we provide recent updates on the mechanisms of action, DST, associated mutations with individual resistance and cross-resistance, clinical efficacy, and pharmacokinetics of CFZ and BDQ against Mtb strains. Presently, known mechanisms of resistance for CFZ and/or BDQ include mutations within the Rv0678, pepQ, Rv1979c, and atpE genes. The cross-resistance between CFZ and BDQ may reduce available MDR-/XDR-TB treatment options. The use of CFZ and BDQ for treatment in the setting of limited DST could allow further spread of drug resistance. The DST and resistance knowledge are urgently needed where CFZ and BDQ resistance do emerge. Therefore, an in-depth understanding of clinical efficacy, DST, cross-resistance, and pharmacokinetics for CFZ and BDQ against Mtb can provide new ideas for improving treatment outcomes, reducing mortality, preventing drug resistance, and TB transmission. Along with this, it will also help to develop rapid molecular diagnostic tools as well as novel therapeutic drugs for TB.

Predictors of Death in Rifampicin Resistant Tuberculosis Patients Treated with the Short Course in Conakry, Guinea

The emergence of rifampicin-resistant tuberculosis (RR-TB) is a major issue for TB control programs due to high risk of treatment failure and death. The objective of this study was to describe survival and to determine predictors of death in RR-TB patients treated with the short regimen (9-11 months) in the Conakry TB treatment centers. Sociodemographic, clinical, and survival data were collected prospectively between 2016 and 2021 on RR-TB patients in the Department of Pneumo-Phtisiology, the Carrière and the Tombolia TB centers. The Kaplan-Meier method was used to estimate the cumulative incidence of death of patients. The Cox regression model was used to identify the predictors independently associated with death. Of 869 patients, 164 (18.9%) patients died during treatment, 126 of them within 120 days of treatment initiation. The factors associated with death during treatment were as follows: patients treated in the Carrière TB center (adjusted hazard ratio [aHR] = 1.65; 95% CI: 1.06-2.59) and in the Department of Pneumo-Phtisiology (aHR = 3.26; 95% CI: 2.10-5.07), patients ≥ 55 years old (aHR = 4.80; 95% CI: 2.81-8.19), patients with no history of first-line TB treatment (aHR = 1.51; 95% CI: 1.05-2.16), and patients living with HIV (aHR = 2.81; 95% CI: 1.94-4.07). The results of this study can help the national TB control program to reconsider its therapeutic strategy to improve patient care in case of RR-TB. Large prospective clinical studies should be conducted to provide evidence of the impact of such factors like previous history of TB treatment and HIV infection on survival of RR-TB patients.

Estimating post-treatment recurrence after multidrug-resistant tuberculosis treatment among patients with and without HIV: the impact of assumptions about death and missing follow-up

Background

Quantification of recurrence risk following successful treatment is crucial to evaluating regimens for multidrug- or rifampicin-resistant (MDR/RR) tuberculosis (TB). However, such analyses are complicated when some patients die or become lost during post-treatment-follow-up.

Methods

We analyzed data on 1,991 patients who successfully completed a longer MDR/RR-TB regimen containing bedaquiline and/or delamanid between 2015 and 2018 in 16 countries. Using five approaches for handling post-treatment deaths, we estimated the six-month post-treatment TB recurrence risk overall, and by HIV status. We used inverse-probability-weighting to account for patients with missing follow-up and investigated the impact of potential bias from excluding these patients without applying inverse-probability weights.

Results

The estimated TB recurrence risk was 6.6 per 1000 (95% confidence interval (CI):3.2,11.2) when deaths were handled as non-recurrences, and 6.7 per 1000 (95% CI:2.8,12.2) when deaths were censored and inverse-probability weights were applied to account for the excluded deaths. The estimated risk of composite recurrence outcomes were 24.2 (95% CI:14.1,37.0), 10.5 (95% CI:5.6,16.6), and 7.8 (95% CI:3.9,13.2) per 1000 for recurrence or 1) any death, 2) death with unknown or TB-related cause, 3) TB-related death, respectively. Corresponding relative risks for HIV status varied in direction and magnitude. Exclusion of patients with missing follow-up without inverse-probability-weighting had a small but apparent impact on estimates.

Conclusion

The estimated six-month TB recurrence risk was low, and the association with HIV status was inconclusive due to few recurrence events. Estimation of post-treatment recurrence will be enhanced by explicit assumptions about deaths and appropriate adjustment for missing follow-up data.

Clofazimine for the treatment of tuberculosis

Shorter (6-9 months), fully oral regimens containing new and repurposed drugs are now the first-choice option for the treatment of drug-resistant tuberculosis (DR-TB). Clofazimine, long used in the treatment of leprosy, is one such repurposed drug that has become a cornerstone of DR-TB treatment and ongoing trials are exploring novel, shorter clofazimine-containing regimens for drug-resistant as well as drug-susceptible tuberculosis. Clofazimine's repurposing was informed by evidence of potent activity against DR-TB strains in vitro and in mice and a treatment-shortening effect in DR-TB patients as part of a multidrug regimen. Clofazimine entered clinical use in the 1950s without the rigorous safety and pharmacokinetic evaluation which is part of modern drug development and current dosing is not evidence-based. Recent studies have begun to characterize clofazimine's exposure-response relationship for safety and efficacy in populations with TB. Despite being better tolerated than some other second-line TB drugs, the extent and impact of adverse effects including skin discolouration and cardiotoxicity are not well understood and together with emergent resistance, may undermine clofazimine use in DR-TB programmes. Furthermore, clofazimine's precise mechanism of action is not well established, as is the genetic basis of clofazimine resistance. In this narrative review, we present an overview of the evidence base underpinning the use and limitations of clofazimine as an antituberculosis drug and discuss advances in the understanding of clofazimine pharmacokinetics, toxicity, and resistance. The unusual pharmacokinetic properties of clofazimine and how these relate to its putative mechanism of action, antituberculosis activity, dosing considerations and adverse effects are highlighted. Finally, we discuss the development of novel riminophenazine analogues as antituberculosis drugs.

The effect of undernutrition on sputum culture conversion and treatment outcomes among people with multidrug-resistant tuberculosis: a systematic review and meta-analysis

OBJECTIVES

We aimed to evaluate the effect of undernutrition on sputum culture conversion and treatment outcomes among people with multidrug-resistant tuberculosis (MDR-TB).

METHODS

We searched for publications in the Medline, Embase, Scopus, and Web of Science databases. We conducted a random-effect meta-analysis to estimate the effects of undernutrition on sputum culture conversion and treatment outcomes. Hazard ratio (HR) for sputum culture conversion and odds ratio (OR) for end-of-treatment outcomes, with 95% CI, were used to summarize the effect estimates. Potential publication bias was checked using funnel plots and Egger's tests.

RESULTS

Of the 2358 records screened, 63 studies comprising a total of 31,583 people with MDR-TB were included. Undernutrition was significantly associated with a longer time to sputum culture conversion (HR 0.7, 95% CI 0.6-0.9, I² = 67·1%), and a higher rate of mortality (OR 2.8, 95% CI 2.1-3.6, I² = 21%) and unsuccessful treatment outcomes (OR 1.8, 95% CI 1.5-2.1, I² = 70%). There was no significant publication bias in the included studies.

CONCLUSION

Undernutrition was significantly associated with unsuccessful treatment outcomes, including mortality and longer time to sputum culture conversion among people with MDR-TB. These findings have implications for supporting targeted nutritional interventions alongside standardized TB drugs.

Ultrasensitive Detection of Multidrug-Resistant Mycobacterium tuberculosis Using SuperSelective Primer-Based Real-Time PCR Assays

The emergence of drug-resistant tuberculosis is a significant global health issue. The presence of heteroresistant Mycobacterium tuberculosis is critical to developing fully drug-resistant tuberculosis cases. The currently available molecular techniques may detect one copy of mutant bacterial genomic DNA in the presence of about 1-1000 copies of wild-type M. tuberculosis DNA. To improve the limit of heteroresistance detection, we developed SuperSelective primer-based real-time PCR assays, which, by their unique assay design, enable selective and exponential amplification of selected point mutations in the presence of abundant wild-type DNA. We designed SuperSelective primers to detect genetic mutations associated with M. tuberculosis resistance to the anti-tuberculosis drugs isoniazid and rifampin. We evaluated the efficiency of our assay in detecting heteroresistant M. tuberculosis strains using genomic DNA isolated from laboratory strains and clinical isolates from the sputum of tuberculosis patients. Results show that our assays detected heteroresistant mutations with a specificity of 100% in a background of up to 10⁴ copies of wild-type M. tuberculosis genomic DNA, corresponding to a detection limit of 0.01%. Therefore, the SuperSelective primer-based RT-PCR assay is an ultrasensitive tool that can efficiently diagnose heteroresistant tuberculosis in clinical specimens and contributes to understanding the drug resistance mechanisms. This approach can improve the management of antimicrobial resistance in tuberculosis and other infectious diseases.

Treatment outcomes for multidrug- and rifampicin-resistant tuberculosis in Central and West Africa: a systematic review and meta-analysis

OBJECTIVES

We aimed to investigate published data on treatment outcomes of multidrug-resistant (MDR)/rifampicin-resistant tuberculosis (TB) in Central and West Africa because these, to the best of our knowledge, are sparsely available.

METHODS

Systematic review and meta-analysis.

RESULTS

A total of 14 studies were included, representing 4268 individuals in 14 of the 26 countries. Using a random-effects model meta-analysis, we observed a pooled success rate of 80.8% (95% confidence interval [CI] 56.0-93.3) for the Central African subgroup and 69.2% (95% CI 56.3-79.7) for the West African subgroup (P = 0.0522). The overall treatment success for all studies was 74.6% (95% CI 65.0-82.2). We found high heterogeneity among included studies (I² = 96.1%). The estimated proportion of successfully treated individuals with MDR/rifampicin-resistant TB was considerably higher than the global estimate provided by the World Health Organization (59%), reaching the 2015 World Health Organization target of at least 75% treatment success for MDR-TB.

CONCLUSION

The use of shorter treatment regimens and the standardized treatment conditions, including directly observed therapy in these studies, could have contributed to a high treatment success. Yet, the available literature was not fully representative of the regions, possibly highlighting the sparse resources in many of these countries. The review was registered at PROSPERO (https://www.crd.york.ac.uk/prospero/) (CRD42022353163).

Failure or relapse predictors for the STREAM Stage 1 short regimen for RR-TB

BACKGROUND: STREAM (Standardised Treatment Regimens of Anti-tuberculosis drugs for Multidrug-Resistant Tuberculosis) Stage 1 demonstrated non-inferior efficacy of a short regimen for rifampicin-resistant TB (RR-TB) compared to a long regimen as recommended by the WHO. The present paper analyses factors associated with a definite or probable failure or relapse (FoR) event in participants receiving the Short regimen.METHODS: This analysis is restricted to 253 participants allocated to the Short regimen and is based on the protocol-defined modified intention to treat (mITT) population. Multivariable Cox regression models were built using backwards elimination with an exit probability of P = 0.157, equivalent to the Akaike Information Criterion, to identify factors independently associated with a definite or probable FoR event.RESULTS: Four baseline factors were identified as being significantly associated with the risk of definite or probable FoR (male sex, a heavily positive baseline smear grade, HIV co-infection and the presence of costophrenic obliteration). There was evidence of association of culture positivity at Week 8 and FoR in a second model and Week 16 smear positivity, presence of diabetes and of smoking in a third model.CONCLUSION: The factors associated with FoR outcomes identified in this analysis should be considered when determining the optimal shortened treatment regimen.

Bedaquiline and Linezolid improve anti-TB treatment outcome in drug-resistant TB patients with HIV: A systematic review and meta-analysis

OBJECTIVES

We aimed to assess the effect of second-line anti-TB treatment and determine which drugs can achieve the greatest clinical benefit for DR-TB-HIV patients by comparing multiple chemotherapy regimens, to provide a basis for evidence-based practice.

METHODS

We searched three electronic databases (PubMed, Web of Science and Cochrane) for related English studies published since 2010. A random-effect model was used to estimate the pooled result for the treatment outcomes. Subgroup analysis based on possible factors, such as ART, baseline CD4 T-cell count, treatment regimens, and profiles of drug resistance, was also conducted to assess factors for favorable outcome. Outcomes were treatment success and mortality.

RESULTS

38 studies, 40 cohorts with 9279 patients were included. The pooled treatment success, mortality, treatment failure, and default rates were 57.5 % (95 % CI 53.1-61.9), 21 % (95 % CI 17.8-24.6), 4.8 % (95 % CI 3.5-6.5), and 10.7 % (95 % CI 8.7-13.1), respectively, in patients with DR-TB and HIV co-infection. Subgroup analysis showed that BDQ and LZD based regimen, and ≥ 2 Group A drugs were associated with a higher treatment success rate. Besides, higher CD4 T-cell count at baseline was also correlated with higher treatment success rate, too.

CONCLUSIONS

Suboptimal anti-TB outcomes underlining the need to expand the application of effective drugs and better regimen in high HIV setting. BDQ and LZD based all-oral regimen and early ART could contribute to higher treatment success, particularly among XDR-TB-HIV patients. Given that all included studies were observational, our findings emphasize the need for high-quality studies to further investigate the optimal treatment regimen for DR-TB-HIV.

High-dose gatifloxacin-based shorter treatment regimens for MDR/RR-TB

SETTING

The shorter treatment regimen (STR) for multidrug- or rifampicin-resistant tuberculosis (MDR/RR-TB) has achieved successful outcomes in many countries. However, there are few studies on high-dose gatifloxacin-based STR with adverse drug reactions (ADRs) and management.

DESIGN

A prospective observational study was conducted with MDR/RR-TB patients who were treated with a standardized 9 or 12 - month regimen: including gatifloxacin (Gfx), clofazimine (Cfz), ethambutol (EMB), and pyrazinamide (PZA), and supplemented by amikacin (Am), isoniazid (INH), and prothionamide (Pto) during an intensive phase of 4 or 6 - month. Monitored ADRs monthly until treatment completion and then followed up every three months for one year.

RESULTS

Among the 42 eligible patients, 35 (83.3%) completed treatment successfully, 1 (2.4%) lost to follow-up (LTFU), and 6 (14.3%) failed due to ADRs, with no death. The most important ADR was drug-induced liver damage, which occurred in 24 out of 42 (57.1%) patients and resulted in 4 (9.5%) failed treatments and 4 (9.5%) adjusted treatments. QT interval prolongation occurred in 17 out of 42 (40.5%) patients, 9 (21.4%) of them with the corrected QT interval according to Fridericia (QTcF) > 500 ms resulting in 7 (16.7%) adjusted treatments.

CONCLUSIONS

This study confirmed the effectiveness of the high-dose gatifloxacin-based STR but severe ADRs, especially hepatotoxicity and QT interval prolongation should never be ignored.

Tuberculosis Treatment Outcome and Predictors in Africa: A Systematic Review and Meta-Analysis

This review aimed to summarize and estimate the TB treatment success rate and factors associated with unsuccessful TB treatment outcomes in Africa. Potentially eligible primary studies were retrieved from PubMed and Google Scholar. The risk of bias and quality of studies was assessed using The Joanna Briggs Institute's (JBI) appraisal criteria, while heterogeneity across studies was assessed using Cochran's Q test and I2 statistic. Publication bias was checked using the funnel plot and egger's test. The protocol was registered in PROSPERO, numbered CRD42019136986. A total of 26 eligible studies were considered. The overall pooled estimate of TB treatment success rate was found to be 79.0% (95% CI: 76-82%), ranging from 53% (95% CI: 47-58%) in Nigeria to 92% (95% CI: 90-93%) in Ethiopia. The majority of unsuccessful outcomes were attributed to 48% (95% CI: 40-57%) death and 47% (95% CI: 39-55%) of defaulter rate. HIV co-infection and retreatment were significantly associated with an increased risk of unsuccessful treatment outcomes compared to HIV negative and newly diagnosed TB patients with RR of 1.53 (95% CI: 1.36-1.71) and 1.48 (95% CI: 1.14-1.94), respectively. TB treatment success rate was 79% below the WHO defined threshold of 85% with significant variation across countries. Countries need to explore contextual underlining factors and more effort is required in providing TB preventive treatment, improve case screening and linkage for TB treatment among HIV high-risk groups and use confirmatory TB diagnostic modality. Countries in Africa need to strengthen counseling and follow-up, socio-economic support for patients at high risk of loss to follow-up and poor treatment success is also crucial for successful TB control programs.

Undernutrition and Treatment Success in Drug-Resistant Tuberculosis in Uganda

Background

Undernutrition is associated with unfavourable treatment outcomes among people with drug-resistant tuberculosis (DRTB). Factors influencing the treatment outcomes among undernourished people with DRTB are not well characterised. The aim of this study was to determine factors associated with treatment success among undernourished people with DRTB in Uganda.

Methods

We analysed data from a retrospective cohort of people with DRTB from 16 treatment sites in Uganda. We included participants with a pre-treatment body mass index (BMI) of <18.5 kilograms/meters² (kg/m²). Participants were categorised as having mild (BMI of 18.5–17 kg/m²), moderate (BMI of 16.9–16.0 kg/m²) or severe (BMI of <16.0 kg/m²) undernutrition. We performed logistic regression analysis to determine factors associated with treatment success.

Results

Among 473 people with DRTB, 276 (58.4%) were undernourished (BMI < 18.5 Kg/m²) and were included in the study. Of these, 92 (33.3%) had mild, 69 (25.0%) had moderate and 115 (41.7%) had severe undernutrition. The overall treatment success rate (TSR) for the undernourished was 71.4% (n = 197). Although the TSR was similar among participants with mild (71.7%), moderate (78.3%) and severe (67.0%) undernutrition (p = 0.258), all treatment failure cases (n =6) were among participants with severe undernutrition (p = 0.010). Cigarette smoking (odds ratio (OR) = 0.19, 95% CI 0.07–0.47, p < 0.001), urban residence (OR = 0.31, 95% CI 0.14–0.70, p = 0.005) and moderate (OR = 0.14, 95% CI 0.06–0.35, p < 0.001) and severe anaemia (OR = 0.06, 95% CI 0.01–0.29, p = 0.001) were associated with lower odds of treatment success.

Conclusion

Most undernourished people with DRTB have severe undernutrition. Smoking and anaemia are modifiable factors which upon appropriate intervention could improve treatment success. The effect of urban residence on the TSR needs to be evaluated further.

Transmission patterns of rifampicin resistant Mycobacterium tuberculosis complex strains in Cameroon: a genomic epidemiological study

Background

Determining factors affecting the transmission of rifampicin (RR) and multidrug-resistant (MDR) Mycobacterium tuberculosis complex strains under standardized tuberculosis (TB) treatment is key to control TB and prevent the evolution of drug resistance.

Methods

We combined bacterial whole genome sequencing (WGS) and epidemiological investigations for 37% (n = 195) of all RR/MDR-TB patients in Cameroon (2012–2015) to identify factors associated with recent transmission.

Results

Patients infected with a strain resistant to high-dose isoniazid, and ethambutol had 7.4 (95% CI 2.6–21.4), and 2.4 (95% CI 1.2–4.8) times increased odds of being in a WGS-cluster, a surrogate for recent transmission. Furthermore, age between 30 and 50 was positively correlated with recent transmission (adjusted OR 3.8, 95% CI 1.3–11.4). We found high drug-resistance proportions against three drugs used in the short standardized MDR-TB regimen in Cameroon, i.e. high-dose isoniazid (77.4%), ethambutol (56.9%), and pyrazinamide (43.1%). Virtually all strains were susceptible to fluoroquinolones, kanamycin, and clofazimine, and treatment outcomes were mostly favourable (87.5%).

Conclusion

Pre-existing resistance to high-dose isoniazid, and ethambutol is associated with recent transmission of RR/MDR strains in our study. A possible contributing factor for this observation is the absence of universal drug susceptibility testing in Cameroon, likely resulting in prolonged exposure of new RR/MDR-TB patients to sub-optimal or failing first-line drug regimens.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06593-8.

A systematic review of the quality of conduct and reporting of survival analyses of tuberculosis outcomes in Africa

BACKGROUND

Survival analyses methods (SAMs) are central to analysing time-to-event outcomes. Appropriate application and reporting of such methods are important to ensure correct interpretation of the data. In this study, we systematically review the application and reporting of SAMs in studies of tuberculosis (TB) patients in Africa. It is the first review to assess the application and reporting of SAMs in this context.

METHODS

Systematic review of studies involving TB patients from Africa published between January 2010 and April 2020 in English language. Studies were eligible if they reported use of SAMs. Application and reporting of SAMs were evaluated based on seven author-defined criteria.

RESULTS

Seventy-six studies were included with patient numbers ranging from 56 to 182,890. Forty-three (57%) studies involved a statistician/epidemiologist. The number of published papers per year applying SAMs increased from two in 2010 to 18 in 2019 (P = 0.004). Sample size estimation was not reported by 67 (88%) studies. A total of 22 (29%) studies did not report summary follow-up time. The survival function was commonly presented using Kaplan-Meier survival curves (n = 51, (67%) studies) and group comparisons were performed using log-rank tests (n = 44, (58%) studies). Sixty seven (91%), 3 (4.1%) and 4 (5.4%) studies reported Cox proportional hazard, competing risk and parametric survival regression models, respectively. A total of 37 (49%) studies had hierarchical clustering, of which 28 (76%) did not adjust for the clustering in the analysis. Reporting was adequate among 4.0, 1.3 and 6.6% studies for sample size estimation, plotting of survival curves and test of survival regression underlying assumptions, respectively. Forty-five (59%), 52 (68%) and 73 (96%) studies adequately reported comparison of survival curves, follow-up time and measures of effect, respectively.

CONCLUSION

The quality of reporting survival analyses remains inadequate despite its increasing application. Because similar reporting deficiencies may be common in other diseases in low- and middle-income countries, reporting guidelines, additional training, and more capacity building are needed along with more vigilance by reviewers and journal editors.

Case Report: Dynamics of Acquired Fluoroquinolone Resistance under Standardized Short-Course Treatment of Multidrug-Resistant Tuberculosis

We report a case of acquired fluoroquinolone (FQ) resistance under short-course multidrug-resistant tuberculosis (MDR-TB) treatment. The patient was managed at Kabutare hospital, one of the two specialized MDR-TB clinics in Rwanda. A low dose of moxifloxacin was used in the first three critical months. Acquired resistance was identified at the ninth month of treatment, 3 months after stopping kanamycin in a strain initially susceptible only to FQs, kanamycin, and clofazimine. Fluoroquinolone resistance was detected in the same month by deep sequencing as routinely used second-line line probe assay and phenotypic drug susceptibility testing. High-dose FQ, preferably gatifloxacin, should be used to maximize effectiveness.

Initial resistance to companion drugs should not be considered an exclusion criterion for the shorter multidrug-resistant tuberculosis treatment regimen

OBJECTIVES

We investigated whether companion drug resistance was associated with adverse outcomes of the shorter multidrug-resistant tuberculosis (MDR-TB) treatment regimen in Bangladesh after adjustment for fluoroquinolone resistance.

METHODS

MDR-TB/rifampicin-resistant tuberculosis patients registered for treatment with a standardized gatifloxacin-based shorter MDR-TB treatment regimen were selected for the study. Drug resistance was determined by the proportion method, gatifloxacin and isoniazid minimum inhibitory concentration testing for selected isolates, and whole-genome sequencing.

RESULTS

Low-level fluoroquinolone resistance and high-level fluoroquinolone resistance were the most important predictors of adverse outcomes, with pyrazinamide resistance having a significant yet lower impact. In patients with fluoroquinolone-/second-line-injectable-susceptible tuberculosis, non-eligibility for the shorter MDR-TB treatment regimen (initial resistance to pyrazinamide, ethionamide, or ethambutol) was not associated with adverse outcome (adjusted odds ratio 1.01; 95% confidence interval 0.4-2.8). Kanamycin resistance was uncommon (1.3%). Increasing levels of resistance to isoniazid predicted treatment failure, also in a subgroup of patients with high-level fluoroquinolone-resistant tuberculosis.

CONCLUSIONS

Our results suggest that resistance to companion drugs in the shorter MDR-TB treatment regimen, except kanamycin resistance, is of no clinical importance as long as fluoroquinolone susceptibility is preserved. Hence, contrary to current WHO guidelines, exclusions to the standard regimen are justified only in the case of fluoroquinolone resistance. and possibly kanamycin resistance.

High rifampicin-resistant TB cure rates and prevention of severe ototoxicity after replacing the injectable by linezolid in early stage of hearing loss

The short treatment regimen (STR) achieves a >80% cure in rifampicin-resistant tuberculosis (RR-TB) patients. However, ototoxicity induced by the injectable is a concern. This is the first study to evaluate the replacement of injectables by linezolid in patients with audiometry abnormalities at baseline or during the treatment.We conducted a retrospective cohort study of all RR-TB patients started on the STR between 2016 and June, 2019, in Niger. Patients underwent audiometry every 2 months in 2016 and every month since 2017.Of 195 patients, 16.9% (33 out of 195) received linezolid from the start (n=17), or switched from injectables to linezolid during treatment (n=16), based on audiometry abnormalities. In 2016, two patients developed severe ototoxicity despite switching to linezolid. Since 2017, no patient developed severe hearing loss or complete deafness. Severe haematological toxicity was observed in 18.1% (six out of 33) of patients on linezolid, none of which was life threatening. The use of linezolid was associated with severe but manageable adverse events (hazard ratio 8.9, 95% CI 2.5-31.5; p=0.001). A total of 90.9% (30 out of 33) of patients on a linezolid-containing STR were cured, and none experienced treatment failure. Three died, but not due to adverse events.Baseline and monthly audiometry monitoring and using linezolid after detection of hearing abnormalities appears effective to prevent severe ototoxicity, while keeping high treatment success and manageable adverse events.

Course of Adverse Events during Short Treatment Regimen in Patients with Rifampicin-Resistant Tuberculosis in Burundi

The introduction of the nine-month short-treatment regimen (STR) has drastically improved outcomes of rifampicin-resistant tuberculosis (RR-TB) treatment. Adverse events (AE) commonly occur, including injectable-induced hearing loss. In Burundi we retrospectively assessed the frequency of adverse events and treatment modifications in all patients who initiated the STR between 2013–2017. Among 225 included patients, 93% were successfully treated without relapse, 5% died, 1% was lost-to-follow-up, 0.4% had treatment failure and 0.4% relapsed after completion. AE were reported in 53%, with grade 3 or 4 AE in 4% of patients. AE occurred after a median of two months. Hepatotoxicity (31%), gastro-intestinal toxicity (22%) and ototoxicity (10%) were most commonly reported. One patient suffered severe hearing loss. Following AE, 7% of patients had a dose reduction and 1% a drug interruption. Kanamycin-induced ototoxicity led to 94% of modifications. All 18 patients with a modified regimen were cured relapse-free. In this exhaustive national RR-TB cohort, RR-TB was treated successfully with the STR. Adverse events were infrequent. To replace the present STR, all-oral regimens should be at least as effective and also less toxic. During and after transition, monitoring, management, and documentation of AE will remain essential.