Improving outcomes for multidrug-resistant tuberculosis: aggressive regimens prevent treatment failure and death

The Association Between Sputum Culture Conversion and Mortality in Cavitary Mycobacterium avium Complex Pulmonary Disease

BACKGROUND

The association between treatment outcome and the mortality of Mycobacterium avium complex pulmonary disease (MAC-PD) with cavitary lesions is unclear. This article assessed the impact of culture conversion on mortality in patients with cavitary MAC-PD.

RESEARCH QUESTION

Is the achievement of sputum culture conversion in MAC-PD with cavitary lesions associated with the prognosis?

STUDY DESIGN AND METHODS

From 2002 to 2020, a total of 351 patients with cavitary MAC-PD (105 with the fibrocavitary type and 246 with the cavitary nodular bronchiectatic type), who had been treated with a ≥ 6-month macrolide-containing regimen at a tertiary referral center in the Republic of Korea, were retrospectively enrolled in this study. All-cause mortality during the follow-up period was analyzed based on culture conversion at the time of treatment completion.

RESULTS

The cohort had a median treatment duration of 14.7 months (interquartile range [IQR], 13.4-16.8 months). Of the 351 patients, 69.8% (245 of 351) achieved culture conversion, and 30.2% (106 of 351) did not. The median follow-up was 4.4 years (IQR, 2.3-8.3 years) in patients with culture conversion and 3.1 years (IQR, 2.1-4.8 years) in those without. For the patients with and without culture conversion, all-cause mortality was 5.3% vs 35.8% (P < .001), and the 5-year cumulative mortality was 20.0% vs 38.4%, respectively. Cox analysis found that a lack of culture conversion was significantly associated with higher mortality (adjusted hazard ratio, 5.73; 95% CI, 2.86-11.50). Moreover, the 2-year landmark analysis revealed a distinct impact of treatment outcome on mortality.

INTERPRETATION

The mortality rate of patients with cavitary MAC-PD who did not achieve culture conversion was significantly higher than that of those with culture conversion.

Predictors of mortality among multidrug-resistant tuberculosis patients in central Ethiopia: a retrospective follow-up study

The burden of multidrug-resistant tuberculosis (MDR-TB) related to mortality in resource-poor countries remains high. This study aimed to estimate the incidence and predictors of death among MDR-TB patients in central Ethiopia. A retrospective follow-up study was conducted at three hospitals in the Amhara region on 451 patients receiving treatment for MDR-TB from September 2010 to January 2017. Data were collected from patient registration books, charts and computer databases. Data were fitted to a parametric frailty model and survival was expressed as an adjusted hazard ratio (AHR) with a 95% confidence interval (CI). The median follow-up time of participants was 20 months (interquartile range: 12, 22) and 46 (10.20%) of patients died during this period. The incidence rate of mortality was 7.42 (95% CI 5.56-9.91)/100 person-years. Older age (AHR = 1.04, 95% CI 1.01-1.08), inability to self-care (AHR = 13.71, 95% CI 5.46-34.40), co-morbidity (AHR = 5.74, 95% CI 2.19-15.08), low body mass index (AHR = 4.13, 95% CI 1.02-16.64), acute lung complications (AHR = 4.22, 95% CI 1.66-10.70) and lung consolidation at baseline (AHR = 5.27, 95% CI 1.06-26.18) were independent predictors of mortality. Most of the identified predictor factors of death in this study were considered to be avoidable if the TB programme had provided nutritional support for malnourished patients and ensured a close follow-up of the elderly, and patients with co-morbidities.

Association Between Duration of Aminoglycoside Treatment and Outcome of Cavitary Mycobacterium avium Complex Lung Disease

BACKGROUND

Although aminoglycosides are recommended for cavitary Mycobacterium avium complex lung disease (MAC-LD), the optimal duration of treatment is unclear. We investigated the association between duration of aminoglycoside treatment and outcomes in cavitary MAC-LD.

METHODS

Among patients diagnosed with macrolide-susceptible cavitary MAC-LD between 2000 and 2013, 101 who received treatment up to August 2017 with a regimen containing aminoglycosides were enrolled at a tertiary referral center in South Korea. Their medical records were retrospectively reviewed. The duration of aminoglycoside treatment was at the discretion of the attending physician.

RESULTS

A total of 75 patients (74.3%) were administered aminoglycosides for ≥3 months (median 164 days), whereas the remaining 26 patients (25.7%) received treatment for <3 months (median 59 days). The overall treatment success rate was 63.4% (64/101). Patients treated with aminoglycosides for ≥3 months had a significantly higher success rate than those treated for <3 months (69.3% vs 46.2%; P = .035). Multivariate analysis revealed that aminoglycoside treatment for ≥3 months was a significant factor for treatment success (adjusted odds ratio, 3.602; 95% confidence interval, 1.249-10.390; P = .018). Recurrence occurred in 8 (22.9%) of 35 patients who were followed up for at least 3 years after the end of treatment; all 8 patients received aminoglycosides for ≥3 months.

CONCLUSIONS

Patients with cavitary MAC-LD treated with aminoglycosides for ≥3 months showed higher treatment success rate than those treated for <3 months. However, treatment for ≥3 months was not associated with the development of recurrence.

Linezolid-Associated Neurologic Adverse Events in Patients with Multidrug-Resistant Tuberculosis, France

Linezolid is one of the most effective drugs for treating multidrug-resistant tuberculosis (MDR TB), but adverse effects remain problematic. We evaluated 57 MDR TB patients who had received >1 dose of linezolid during 2011–2016. Overall, patients received 600 mg/day of linezolid for a median of 13 months. In 33 (58%) patients, neurologic or ophthalmologic signs developed, and 18 (32%) had confirmed peripheral neuropathy, which for 78% was irreversible at 12 months after the end of TB treatment despite linezolid withdrawal. Among the 19 patients who underwent ophthalmologic evaluation, 14 patients had optic neuropathy that fully reversed for 2. A total of 16 (33%) of 49 patients had a linezolid trough concentration >2 mg/L, and among these, 14 (88%) experienced adverse effects. No significant association was found between trough concentration and neurologic toxicity. These findings suggest the need to closely monitor patients for neurologic signs and discuss optimal duration of linezolid treatment.

Adjunctive Host-Directed Therapy With Statins Improves Tuberculosis-Related Outcomes in Mice

BACKGROUND

Tuberculosis (TB) treatment is lengthy and complicated and patients often develop chronic lung disease. Recent attention has focused on host-directed therapies aimed at optimizing immune responses to Mycobacterium tuberculosis (Mtb), as adjunctive treatment given with antitubercular drugs. In addition to their cholesterol-lowering properties, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have broad anti-inflammatory and immunomodulatory activities.

METHODS

In the current study, we screened 8 commercially available statins for cytotoxic effect, anti-TB activity, synergy with first-line drugs in macrophages, pharmacokinetics and adjunctive bactericidal activity, and, in 2 different mouse models, as adjunctive therapy to first-line TB drugs.

RESULTS

Pravastatin showed the least toxicity in THP-1 and Vero cells. At nontoxic doses, atorvastatin and mevastatin were unable to inhibit Mtb growth in THP-1 cells. Simvastatin, fluvastatin, and pravastatin showed the most favorable therapeutic index and enhanced the antitubercular activity of the first-line drugs isoniazid, rifampin, and pyrazinamide in THP-1 cells. Pravastatin modulated phagosomal maturation characteristics in macrophages, phenocopying macrophage activation, and exhibited potent adjunctive activity in the standard mouse model of TB chemotherapy and in a mouse model of human-like necrotic TB lung granulomas.

CONCLUSIONS

These data provide compelling evidence for clinical evaluation of pravastatin as adjunctive, host-directed therapy for TB.

Increased prevalence of levofloxacin-resistant Mycobacterium tuberculosis in China is associated with specific mutations within the gyrA gene

OBJECTIVES

To compare the prevalence of levofloxacin (LFX) resistance and the population structure of Mycobacterium tuberculosis (MTB) with different mutations conferring LFX resistance between 2005 and 2015.

METHODS

A total 542 MTB isolates were randomly selected from pulmonary tuberculosis (TB) patients in 2005 and 2015 and analyzed regarding minimum inhibitory concentrations (MICs) and quinolone resistance-determining regions (QRDR).

RESULTS

One hundred and eleven of the 542 MTB isolates analyzed (20.5%) were resistant to LFX. There were 42 and 69 LFX-resistant isolates from 2005 and 2015, respectively, and MIC high-level LFX resistance was significantly higher in 2015 (40.6%, 28/69) than in 2005 (16.7%, 7/42) (p = 0.02). There were 87 (78.4%) mutations of these 111 LFX-resistant isolates. In addition, a significant difference in proportion was observed in the isolates with mutations in codon 90 of the gyrA gene between 2005 and 2015 (11.9% in 2005 versus 29.0% in 2015, p = 0.04).

CONCLUSIONS

There was an alarming increase in prevalence of LFX-resistant TB in China between 2005 and 2015. This dynamic change is mostly attributed to the increase in high-level LFX resistance. Moreover, a significant difference was noted in the proportion of LFX-resistant isolates harboring specific mutations within the gyrA gene between 2005 and 2015.

Treatment Outcomes of Multidrug-Resistant Tuberculosis in Taiwan: Tackling Loss to Follow-up

Background

The proportion of treatment success among patients with multidrug-resistant tuberculosis (MDR-TB) enrolled between 1992 and 1996 was 51.2%, and that among patients enrolled between 2000 and April 2007 was 61%. To address the challenge of MDR-TB, the Taiwan MDR-TB Consortium (TMTC) was established in May 2007. To assess the performance of the TMTC, we analyzed the data of patients enrolled in its first 5 years.

Methods

Comprehensive care was provided at no cost to patients, who were usually hospitalized for 1 month initially. Treatment regimens consisted of 4–5 drugs and the duration of treatment was 18–24 months. A case manager and a directly observed therapy provider were assigned to each patient. Psychosocial support was provided to address emotional stress and stigma. Financial support was offered to avoid the financial hardship faced by patients and their families. We assessed treatment outcomes at 30 months using internationally recommended outcome definitions.

Results

Of the 692 MDR-TB patients, 570 (82.4%) were successfully treated, 84 (12.1%) died, 18 (2.6%) had treatment failure, and 20 (2.9%) were lost to follow-up. Age ≥65 years (adjusted odds ratio [aOR], 6.78 [95% confidence interval {CI}, 3.14–14.63]), cancer (aOR, 11.82 [95% CI, 5.55–25.18]), and chronic kidney disease (aOR, 3.62 [95% CI, 1.70–7.71]) were significantly associated with death. Resistance to fluoroquinolone (aOR, 10.89 [95% CI, 3.97–29.88]) was significantly associated with treatment failure.

Conclusions

The TMTC, which operates under a strong collaboration between the public health authority and clinical teams, has been a highly effective model of care in the management of MDR-TB.

Factors affecting outcomes of individualised treatment for drug resistant tuberculosis in an endemic region

BACKGROUND

Individualised treatment regimens for drug resistant tuberculosis have improved outcomes. This retrospective observational study examined potential factors that affect individualised treatment in an endemic region, and highlighted predictors of a successful outcome.

METHODS

We examined records of proven MDR, pre-XDR and XDR TB patients diagnosed and started on treatment between 2010 and 2014, and collected the following data for each patient: age, gender, comorbidities, past history of TB, diagnosis, site of disease, drug susceptibility testing (DST) results, treatment, adverse reactions to anti-tubercular drugs, treatment changes and outcomes, which were recorded as positive, negative or neutral. Tests of association were carried out between factors and outcomes, following which multiple logistic regression analysis was done to determine the predictors of a positive outcome such as patient cured after completion of treatment at 18 months or longer.

RESULTS

Fifty-nine patients completed treatment at our centre. The median age was 26 years (range 8-65 years). There were 31 (52.5%) female patients. Forty-four (74.6%) were successfully treated over a median treatment period of 23 months (range 18-30 months). Successful outcomes were associated with age less than 45 years (P=0.01, OR=6.67, 95% CI=1.73-23.47), resistance to fewer than five drugs (P=0.001, OR=9.51, 95% CI=2.50-38.18) and susceptibility to Group 4 drugs (P=0.04, OR=4.71, 95% CI=1.03-16.83).

CONCLUSIONS

Age and drug susceptibility were important predictors of treatment outcome.

Linezolid for drug-resistant pulmonary tuberculosis

BACKGROUND

Linezolid was recently re-classified as a Group A drug by the World Health Organization (WHO) for treatment of multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), suggesting that it should be included in the regimen for all patients unless contraindicated. Linezolid use carries a considerable risk of toxicity, with the optimal dose and duration remaining unclear. Current guidelines are mainly based on evidence from observational non-comparative studies.

OBJECTIVES

To assess the efficacy of linezolid when used as part of a second-line regimen for treating people with MDR and XDR pulmonary tuberculosis, and to assess the prevalence and severity of adverse events associated with linezolid use in this patient group.

SEARCH METHODS

We searched the following databases: the Cochrane Infectious Diseases Specialized Register; CENTRAL; MEDLINE; Embase; and LILACS up to 13 July 2018. We also checked article reference lists and contacted researchers in the field.

SELECTION CRITERIA

We included studies in which some participants received linezolid, and others did not. We included randomized controlled trials (RCTs) of linezolid for MDR and XDR pulmonary tuberculosis to evaluate efficacy outcomes. We added non-randomized cohort studies to evaluate adverse events.Primary outcomes were all-cause and tuberculosis-associated death, treatment failure, and cure. Secondary outcomes were treatment interrupted, treatment completed, and time to sputum culture conversion. We recorded frequency of all and serious adverse events, adverse events leading to drug discontinuation or dose reduction, and adverse events attributed to linezolid, particularly neuropathy, anaemia, and thrombocytopenia.

DATA COLLECTION AND ANALYSIS

Two review authors (BS and DC) independently assessed the search results for eligibility and extracted data from included studies. All review authors assessed risk of bias using the Cochrane 'Risk of bias' tool for RCTs and the ROBINS-I tool for non-randomized studies. We contacted study authors for clarification and additional data when necessary.We were unable to perform a meta-analysis as one of the RCTs adopted a study design where participants in the study group received linezolid immediately and participants in the control group received linezolid after two months, and therefore there were no comparable data from this trial. We deemed meta-analysis of non-randomized study data inappropriate.

MAIN RESULTS

We identified three RCTs for inclusion. One of these studies had serious problems with allocation of the study drug and placebo, so we could not analyse data for intervention effect from it. The remaining two RCTs recruited 104 participants. One randomized 65 participants to receive linezolid or not, in addition to a background regimen; the other randomized 39 participants to addition of linezolid to a background regimen immediately, or after a delay of two months. We included 14 non-randomized cohort studies (two prospective, 12 retrospective), with a total of 1678 participants.Settings varied in terms of income and tuberculosis burden. One RCT and 7 out of 14 non-randomized studies commenced recruitment in or after 2009. All RCT participants and 38.7% of non-randomized participants were reported to have XDR-TB.Dosing and duration of linezolid in studies were variable and reported inconsistently. Daily doses ranged from 300 mg to 1200 mg; some studies had planned dose reduction for all participants after a set time, others had incompletely reported dose reductions for some participants, and most did not report numbers of participants receiving each dose. Mean or median duration of linezolid therapy was longer than 90 days in eight of the 14 non-randomized cohorts that reported this information.Duration of participant follow-up varied between RCTs. Only five out of 14 non-randomized studies reported follow-up duration.Both RCTs were at low risk of reporting bias and unclear risk of selection bias. One RCT was at high risk of performance and detection bias, and low risk for attrition bias, for all outcomes. The other RCT was at low risk of detection and attrition bias for the primary outcome, with unclear risk of detection and attrition bias for non-primary outcomes, and unclear risk of performance bias for all outcomes. Overall risk of bias for the non-randomized studies was critical for three studies, and serious for the remaining 11.One RCT reported higher cure (risk ratio (RR) 2.36, 95% confidence interval (CI) 1.13 to 4.90, very low-certainty evidence), lower failure (RR 0.26, 95% CI 0.10 to 0.70, very low-certainty evidence), and higher sputum culture conversion at 24 months (RR 2.10, 95% CI 1.30 to 3.40, very low-certainty evidence), amongst the linezolid-treated group than controls, with no differences in other primary and secondary outcomes. This study also found more anaemia (17/33 versus 2/32), nausea and vomiting, and neuropathy (14/33 versus 1/32) events amongst linezolid-receiving participants. Linezolid was discontinued early and permanently in two of 33 (6.1%) participants who received it.The other RCT reported higher sputum culture conversion four months after randomization (RR 2.26, 95% CI 1.19 to 4.28), amongst the group who received linezolid immediately compared to the group who had linezolid initiation delayed by two months. Linezolid was discontinued early and permanently in seven of 39 (17.9%) participants who received it.Linezolid discontinuation occurred in 22.6% (141/624; 11 studies), of participants in the non-randomized studies. Total, serious, and linezolid-attributed adverse events could not be summarized quantitatively or comparatively, due to incompleteness of data on duration of follow-up and numbers of participants experiencing events.

AUTHORS' CONCLUSIONS

We found some evidence of efficacy of linezolid for drug-resistant pulmonary tuberculosis from RCTs in participants with XDR-TB but adverse events and discontinuation of linezolid were common. Overall, there is a lack of comparative data on efficacy and safety. Serious risk of bias and heterogeneity in conducting and reporting non-randomized studies makes the existing, mostly retrospective, data difficult to interpret. Further prospective cohort studies or RCTs in high tuberculosis burden low-income and lower-middle-income countries would be useful to inform policymakers and clinicians of the efficacy and safety of linezolid as a component of drug-resistant TB treatment regimens.

Use of predicted vital status to improve survival analysis of multidrug-resistant tuberculosis cohorts

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) cohorts often lack long-term survival data, and are summarized instead by initial treatment outcomes. When using Cox proportional hazards models to analyze these cohorts, this leads to censoring subjects at the time of the initial treatment outcome, instead of them providing full survival data. This may violate the non-informative censoring assumption of the model and may produce biased effect estimates. To address this problem, we develop a tool to predict vital status at the end of a cohort period using the initial treatment outcome and assess its ability to reduce bias in treatment effect estimates.

METHODS

We derive and apply a logistic regression model to predict vital status at the end of the cohort period and modify the unobserved survival outcomes to better match the predicted survival experience of study subjects. We compare hazard ratio estimates for effect of an aggressive treatment regimen from Cox proportional hazards models using time to initial treatment outcome, predicted vital status, and true vital status at the end of the cohort period.

RESULTS

Models fit from initial treatment outcomes underestimate treatment effects by up to 22.1%, while using predicted vital status reduced this bias by 5.4%. Models utilizing the predicted vital status produce effect estimates consistently stronger and closer to the true treatment effect than estimates produced by models using the initial treatment outcome.

CONCLUSIONS

Although studies often use initial treatment outcomes to estimate treatment effects, this may violate the non-informative censoring assumption of the Cox proportional hazards model and result in biased treatment effect estimates. Using predicted vital status at the end of the cohort period may reduce this bias in the analyses of MDR-TB treatment cohorts, yielding more accurate, and likely larger, treatment effect estimates. Further, these larger effect sizes can have downstream impacts on future study design by increasing power and reducing sample size needs.

Pulmonary resection for patients with multidrug-resistant tuberculosis based on survival outcomes: a systematic review and meta-analysis

We investigated the survival benefit of pulmonary resection for patients with multidrug-resistant tuberculosis. To weigh the survival benefit of pulmonary resection for patients with multidrug-resistant tuberculosis who have undergone surgical treatment combined with medical chemotherapy compared with medical chemotherapy alone, we did a meta-analysis of available studies containing a hazard ratio for pulmonary resection. Among 1726 articles, 6 clinical reports, with a mean sample size of 47 patients per report, met the inclusion criteria. The pooled hazard ratio of 0.68 with a 95% confidence interval of approximately 0.44-1.07 suggested that the survival benefit of surgical pulmonary resection combined with chemotherapy, in a comparison of the groups 'with surgery' and 'without surgery', is not significantly greater than that of chemotherapy alone. Selection bias, due to the absence of rigid predetermined indications for pulmonary resection, limited the validity of this analysis. Due to the heterogeneity of the patient groups, greater attention is required to compute additional hazard ratios in future studies with stratification of factors such as cardiopulmonary functions, disease extent and the presence of a cavity. These additional computations in future studies are necessary to determine the survival benefit and to support the rigid surgical indications.

Prevalence of pyrazinamide resistance and Wayne assay performance analysis in a tuberculosis cohort in Lima, Peru

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) regimens often contain pyrazinamide (PZA) even if susceptibility to the drug has not been confirmed. This gap is due to the limited availability and reliability of PZA susceptibility testing.

OBJECTIVES

To estimate the prevalence of PZA resistance using the Wayne assay among TB patients in Lima, Peru, to describe characteristics associated with PZA resistance and to compare the performance of Wayne with that of BACTEC™ MGIT™ 960.

METHODS

PZA susceptibility using the Wayne assay was tested in patients diagnosed with culture-positive pulmonary TB from September 2009 to August 2012. Factors associated with PZA resistance were evaluated. We compared the performance of the Wayne assay to that of MGIT 960 in a convenience sample.

RESULTS

The prevalence of PZA resistance was 6.6% (95%CI 5.8-7.5) among 3277 patients, and 47.7% (95%CI 42.7-52.6) among a subset of 405 MDR-TB patients. In multivariable analysis, MDR-TB (OR 86.0, 95%CI 54.0-136.9) and Latin American-Mediterranean lineage (OR 3.40, 95%CI 2.33-4.96) were associated with PZA resistance. The Wayne assay was in agreement with MGIT 960 in 83.9% of samples (κ 0.66, 95%CI 0.56-0.76).

CONCLUSION

PZA resistance was detected using the Wayne assay in nearly half of MDR-TB patients in Lima. This test can inform the selection and composition of regimens, especially those dependent on additional resistance.

Time to Multidrug-Resistant Tuberculosis Treatment Initiation in Association with Treatment Outcomes in Shanghai, China

In high tuberculosis (TB)-burden countries such as China, the diagnosis of multidrug-resistant tuberculosis (MDR-TB) using conventional drug susceptibility testing (DST) takes months, making treatment delay inevitable. Poor outcomes of MDR-TB might be associated with delayed, even inappropriate, treatment. The purposes of this study were to investigate the time to MDR-TB treatment initiation and to assess the association between early treatment and treatment outcomes. Between April 2011 and December 2014, this population-based retrospective cohort study collected the demographic and clinical characteristics and the drug susceptibility profiles of all registered MDR-TB patients in Shanghai, China. The dates of TB and MDR-TB diagnoses, DST performance, and treatment initiation were extracted to calculate the times to treatment. In total, 284 of 346 MDR-TB patients were eligible for analysis, and 68.3% (194/284) had favored outcomes. The median time to treatment initiation from TB diagnosis was 172 days among those with favored outcomes and 190 days among those with poor outcomes. Treatments initiated within 60 days after performing DST (odds ratio [OR], 2.56; 95% confidence interval [CI], 1.22 to 5.36) and empirical treatments (OR, 2.09; 95% CI, 1.01 to 4.32) were positively associated with favored outcomes. Substantial delays to MDR-TB treatment were observed when conventional DST was used. Early treatment predicted favored outcomes. Rapid diagnostic methods should be scaled up and improvements should be made in patient management and information linkage to reduce treatment delay.

Comorbidities and treatment outcomes in multidrug resistant tuberculosis: a systematic review and meta-analysis

Little is known about the impact of comorbidities on multidrug resistant (MDR) and extensively drug resistant (XDR) tuberculosis (TB) treatment outcomes. We aimed to examine the effect of human immunodeficiency virus (HIV), diabetes, chronic kidney disease (CKD), alcohol misuse, and smoking on MDR/XDRTB treatment outcomes. We searched MEDLINE, EMBASE, Cochrane Central Registrar and Cochrane Database of Systematic Reviews as per PRISMA guidelines. Eligible studies were identified and treatment outcome data were extracted. We performed a meta-analysis to generate a pooled relative risk (RR) for unsuccessful outcome in MDR/XDRTB treatment by co-morbidity. From 2457 studies identified, 48 reported on 18,257 participants, which were included in the final analysis. Median study population was 235 (range 60-1768). Pooled RR of unsuccessful outcome was higher in people living with HIV (RR = 1.41 [95%CI: 1.15-1.73]) and in people with alcohol misuse (RR = 1.45 [95%CI: 1.21-1.74]). Outcomes were similar in people with diabetes or in people that smoked. Data was insufficient to examine outcomes in exclusive XDRTB or CKD cohorts. In this systematic review and meta-analysis, alcohol misuse and HIV were associated with higher pooled OR of an unsuccessful outcome in MDR/XDRTB treatment. Further research is required to understand the role of comorbidities in driving unsuccessful treatment outcomes.

Clinical outcome of multidrug-resistant tuberculosis patients receiving standardized second-line treatment regimen in China

OBJECTIVES

The aim of this study was to retrospectively analyze the clinical outcome and the risk factors associated with poor outcome of MDR-TB patients receiving standardized second-line treatment regimen in China.

METHODS

Between January 2008 and December 2010, a total of 12,100 clinical diagnosed TB cases at high risk of drug-resistant TB (DR-TB) were enrolled in this study. Routine follow-up tests were conducted every month during the 6-month intensive phase, and every two months during the 18-month continuation phase.

RESULTS

On the basis of phenotypical drug susceptibility test (DST) results, 2322 MDR-TB patients were confirmed, of which 1542 further received standardized second-line anti-TB regimen. The treatment success rate was 47.6% (734/1542): 688 patients (44.6%) were cured and 46 (3.0%) completed treatment. The percentage of cases with favorable outcome in previously untreated patients (57.6%) was significantly higher than that in treatment-experienced patients (46.1%, OR: 1.58, 95% CI: 1.17-2.14). In addition, a significant lower percentage of male MDR-TB cases with favorable outcome (45.8%) was observed using female MDR-TB cases as a reference (52.0%, OR: 1.31, 95% CI: 1.03-1.60). The proportion of MDR-TB cases with favorable outcome was significantly decreased in older age groups.

CONCLUSIONS

In conclusion, our data demonstrate that less than half of these patients receiving standardized second-line treatment regimen meet the definition of successful treatment during a 3-year period in China. More attention should be paid to the MDR-TB population at high-risk of poor clinical outcome, including male, elderly age, and those who have received prior treatment.

Management of MDR-TB in HIV co-infected patients in Eastern Europe: Results from the TB:HIV study

OBJECTIVES

Mortality among HIV patients with tuberculosis (TB) remains high in Eastern Europe (EE), but details of TB and HIV management remain scarce.

METHODS

In this prospective study, we describe the TB treatment regimens of patients with multi-drug resistant (MDR) TB and use of antiretroviral therapy (ART).

RESULTS

A total of 105 HIV-positive patients had MDR-TB (including 33 with extensive drug resistance) and 130 pan-susceptible TB. Adequate initial TB treatment was provided for 8% of patients with MDR-TB compared with 80% of those with pan-susceptible TB. By twelve months, an estimated 57.3% (95%CI 41.5-74.1) of MDR-TB patients had started adequate treatment. While 67% received ART, HIV-RNA suppression was demonstrated in only 23%.

CONCLUSIONS

Our results show that internationally recommended MDR-TB treatment regimens were infrequently used and that ART use and viral suppression was well below the target of 90%, reflecting the challenging patient population and the environment in which health care is provided. Urgent improvement of management of patients with TB/HIV in EE, in particular for those with MDR-TB, is needed and includes widespread access to rapid TB diagnostics, better access to and use of second-line TB drugs, timely ART initiation with viral load monitoring, and integration of TB/HIV care.

WHO Treatment Guidelines for Drug-Resistant Tuberculosis, 2016 Update: Applicability in South Korea

Despite progress made in tuberculosis control worldwide, the disease burden and treatment outcome of multidrug-resistant tuberculosis (MDR-TB) patients have remained virtually unchanged. In 2016, the World Health Organization released new guidelines for the management of MDR-TB. The guidelines are intended to improve detection rate and treatment outcome for MDR-TB through novel, rapid molecular testing and shorter treatment regimens. Key changes include the introduction of a new, shorter MDR-TB treatment regimen, a new classification of medicines and updated recommendations for the conventional MDR-TB regimen. This paper will review these key changes and discuss the potential issues with regard to the implementation of these guidelines in South Korea.

Risk factors for poor multidrug-resistant tuberculosis treatment outcomes in Kyiv Oblast, Ukraine

Background

Ukraine is among ten countries with the highest burden of multidrug- resistant TB (MDR-TB) worldwide. Treatment success rates for MDR-TB in Ukraine remain below global success rates as reported by the World Health Organization. Few studies have evaluated predictors of poor MDR-TB outcomes in Ukraine.

Methods

We conducted a retrospective analysis of patients initiated on MDR-TB treatment in the Kyiv Oblast of Ukraine between January 01, 2012 and March 31st, 2015. We defined good treatment outcomes as cure or completion and categorized poor outcomes among those who died, failed treatment or defaulted. We used logistic regression analyses to identify baseline patient characteristics associated with poor MDR-TB treatment outcomes.

Results

Among 360 patients, 65 (18.1%) achieved treatment cure or completion while 131 (36.4%) died, 115 (31.9%) defaulted, and 37 (10.3%) failed treatment. In the multivariate analysis, the strongest baseline predictors of poor outcomes were HIV infection without anti-retroviral therapy (ART) initiation (aOR 10.07; 95% CI 1.20–84.45; p 0.03) and presence of extensively-drug resistant TB (aOR 9.19; 95% CI 1.17–72.06; p 0.03). HIV-positive patients initiated on ART were not at increased risk of poor outcomes (aOR 1.43; 95% CI 0.58–3.54; p 0.44). There was no statistically significant difference in risk of poor outcomes among patients who received baseline molecular testing with Gene Xpert compared to those who were not tested (aOR 1.31; 95% CI 0.63–2.73).

Conclusions

Rigorous compliance with national guidelines recommending prompt initiation of ART among HIV/TB co-infected patients and use of drug susceptibility testing results to construct treatment regimens can have a major impact on improving MDR-TB treatment outcomes in Ukraine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2230-2) contains supplementary material, which is available to authorized users.

Undertreated HIV and drug-resistant tuberculosis at a referral hospital in Irkutsk, Siberia

SETTING

A referral hospital for tuberculosis (TB) in Irkutsk, the Russian Federation.

OBJECTIVE

To describe disease characteristics, treatment and hospital outcomes of TB-HIV (human immunodeficiency virus).

DESIGN

Observational cohort of HIV-infected patients admitted for anti-tuberculosis treatment over 6 months.

RESULTS

A total of 98 patients were enrolled with a median CD4 count of 147 cells/mm(3) and viral load of 205 943 copies/ml. Among patients with drug susceptibility testing (DST) results, 29 (64%) were multidrug-resistant (MDR), including 12 without previous anti-tuberculosis treatment. Nineteen patients were on antiretroviral therapy (ART) at admission, and 10 (13% ART-naïve) were started during hospitalization. Barriers to timely ART initiation included death, in-patient treatment interruption, and patient refusal. Of 96 evaluable patients, 21 (22%) died, 14 (15%) interrupted treatment, and 10 (10%) showed no microbiological or radiographic improvement. Patients with a cavitary chest X-ray (aOR 7.4, 95%CI 2.3-23.7, P = 0.001) or central nervous system disease (aOR 6.5, 95%CI 1.2-36.1, P = 0.03) were more likely to have one of these poor outcomes.

CONCLUSION

High rates of MDR-TB, treatment interruption and death were found in an HIV-infected population hospitalized in Irkutsk. There are opportunities for integration of HIV and TB services to overcome barriers to timely ART initiation, increase the use of anti-tuberculosis regimens informed by second-line DST, and strengthen out-patient diagnosis and treatment networks.

Treatment Outcomes for Adolescents With Multidrug-Resistant Tuberculosis in Lima, Peru

Treatment outcomes for adolescents with multidrug-resistant tuberculosis are rarely reported and, to date, have been poor. Among 90 adolescents from Lima, Peru, 68 (75.6%) achieved cure or completion of treatment. Unsuccessful treatment was less common in the Peru cohort than previously described in the literature.

Tuberculosis. Digging deep in the soul of humanity

Tuberculosis (TB) is one of the oldest infectious diseases that affected humankind. A quintessential social disease, TB remains one of the world's deadliest communicable diseases, with still a high mortality and burden of disease. Social representations of TB focus on aspects associated to feelings and manifestations awakened by the disease, sometimes reinforcing stigmas and prejudices about the way of perceiving TB. TB is a historic disease now reborn with a deeper social stigma. Despite the modest reduction in TB incidence worldwide, its incidence is still rising in certain crisis-affected populations like refugees, and in those bearing high prevalence of HIV, persisting poverty, especially in the developing world. Fear and stigma may appear justified with the increasing rates of multi-drug resistant (MDR) TB, and now extremely drug resistant (XDR) TB. However, stigmatization of TB poses serious obstacles to current TB control efforts, as socio-cultural aspects can influence adherence to TB treatment.

Baseline Predictors of Treatment Outcomes in Children With Multidrug-Resistant Tuberculosis: A Retrospective Cohort Study

BACKGROUND

Globally, >30 000 children fall sick with multidrug-resistant (MDR) tuberculosis every year. Without robust pediatric data, clinical management follows international guidelines that are based on studies in adults and expert opinion. We aimed to identify baseline predictors of death, treatment failure, and loss to follow-up among children with MDR tuberculosis disease treated with regimens tailored to their drug susceptibility test (DST) result or to the DST result of a source case.

METHODS

This retrospective cohort study included all children ≤15 years old with confirmed and probable MDR tuberculosis disease who began tailored regimens in Lima, Peru, between 2005 and 2009. Using logistic regression, we examined associations between baseline patient and treatment characteristics and (1) death or treatment failure and (2) loss to follow-up.

RESULTS

Two hundred eleven of 232 (90.9%) children had known treatment outcomes, of whom 163 (77.2%) achieved cure or probable cure, 29 (13.7%) were lost to follow-up, 10 (4.7%) experienced treatment failure, and 9 (4.3%) died. Independent baseline predictors of death or treatment failure were the presence of severe disease (adjusted odds ratio [aOR], 4.96; 95% confidence interval [CI], 1.61-15.26) and z score ≤-1 (aOR, 3.39; 95% CI, 1.20-9.54). We did not identify any independent predictors of loss to follow-up.

CONCLUSIONS

High cure rates can be achieved in children with MDR tuberculosis using tailored regimens containing second-line drugs. However, children faced significantly higher risk of death or treatment failure if they had severe disease or were underweight. These findings highlight the need for early interventions that can improve treatment outcomes for children with MDR tuberculosis.

New Antituberculosis Drugs: From Clinical Trial to Programmatic Use

Treatment of multidrug-resistant tuberculosis (MDR-TB) cases is challenging because it relies on second-line drugs that are less potent and more toxic than those used in the clinical management of drug-susceptible TB. Moreover, treatment outcomes for MDR-TB are generally poor compared to drug sensitive disease, highlighting the need for of new drugs. For the first time in more than 50 years, two new anti-TB drugs were approved and released. Bedaquiline is a first-in-class diarylquinoline compound that showed durable culture conversion at 24 weeks in phase IIb trials. Delamanid is the first drug of the nitroimidazole class to enter clinical practice. Similarly to bedaquiline results of phase IIb studies showed increased sputum-culture conversion at 2 months and better final treatment outcomes in patients with MDR-TB. Among repurposed drugs linezolid and carbapenems may represent a valuable drug to treat cases of MDR and extensively drug-resistant TB. The recommended regimen for MDR-TB is the combination of at least four drugs to which M. tuberculosis is likely to be susceptible for the duration of 20 months. Drugs are chosen with a stepwise selection process through five groups on the basis of efficacy, safety, and cost. Clinical phase III trials on new regimen are ongoing that could prove transformative against MDR-TB, by being shorter (six months), simpler (an all-oral regimen) and safer than current standard therapy. It is fundamental that the adoption of the new drugs is done responsibly to avoid inappropriate use. Concentration of in-patient MDR-TB treatment in specialized centers could be considered in countries with low numbers of cases in order to provide appropriate clinical case management and to prevent emergence of drug resistance.

Aggressive Regimens Reduce Risk of Recurrence After Successful Treatment of MDR-TB

BACKGROUND

We sought to determine whether treatment with a "long aggressive regimen" was associated with lower rates of relapse among patients successfully treated for pulmonary multidrug-resistant tuberculosis (MDR-TB) in Tomsk, Russia.

METHODS

We conducted a retrospective cohort study of adult patients that initiated MDR-TB treatment with individualized regimens between September 2000 and November 2004, and were successfully treated. Patients were classified as having received "aggressive regimens" if their intensive phase consisted of at least 5 likely effective drugs (including a second-line injectable and a fluoroquinolone) used for at least 6 months post culture conversion, and their continuation phase included at least 4 likely effective drugs. Patients that were treated with aggressive regimens for a minimum duration of 18 months post culture conversion were classified as having received "long aggressive regimens." We used recurrence as a proxy for relapse because genotyping was not performed. After treatment, patients were classified as having disease recurrence if cultures grew MDR-TB or they re-initiated MDR-TB therapy. Data were analyzed using Cox proportional hazard regression.

RESULTS

Of 408 successfully treated patients, 399 (97.5%) with at least 1 follow-up visit were included. Median duration of follow-up was 42.4 months (interquartile range: 20.5-59.5), and there were 27 recurrence episodes. In a multivariable complete case analysis (n = 371 [92.9%]) adjusting for potential confounders, long aggressive regimens were associated with a lower rate of recurrence (adjusted hazard ratio: 0.22, 95% confidence interval, .05-.92).

CONCLUSIONS

Long aggressive regimens for MDR-TB treatment are associated with lower risk of disease recurrence.

The effect of early versus late treatment initiation after diagnosis on the outcomes of patients treated for multidrug-resistant tuberculosis: a systematic review

BACKGROUND

Globally it is estimated that 480 000 people developed multidrug-resistant tuberculosis (MDR-TB) in 2014 and 190 000 people died from the disease. Successful treatment outcomes are achieved in only 50 % of patients with MDR-TB, compared to 86 % for drug susceptible disease. It is widely held that delay in time to initiation of treatment for MDR-TB is an important predictor of treatment outcome. The objective of this review was to assess the existing evidence on the outcomes of multidrug- and extensively drug-resistant tuberculosis patients treated early (≤4 weeks) versus late (>4 weeks) after diagnosis of drug resistance.

METHODS

Eight sources providing access to 17 globally representative electronic health care databases, indexes, sources of evidence-based reviews and grey literature were searched using terms incorporating time to treatment and MDR-TB. Two-stage sifting in duplicate was employed to assess studies against pre-specified inclusion and exclusion criteria. Only those articles reporting WHO-defined treatment outcomes were considered for inclusion. Articles reporting on fewer than 10 patients, published before 1990, or without a comparison of outcomes in patient groups experiencing different delays to treatment initiation were excluded.

RESULTS

The initial search yielded 1978 references, of which 1475 unique references remained after removal of duplicates and 28 articles published pre-1990. After title and abstract sifting, 64 papers underwent full text review. None of these articles fulfilled the criteria for inclusion in the review.

CONCLUSIONS

Whilst there is an inherent logic in the theory that treatment delay will lead to poorer treatment outcomes, no published evidence was identified in this systematic review to support this hypothesis. Reports of programmatic changes leading to reductions in treatment delay exist in the literature, but attribution of differences in outcomes specifically to treatment delay is confounded by other contemporaneous changes. Further primary research on this question is not considered a high priority use of limited resources, though where data are available, improved reporting of outcomes by time to treatment should be encouraged.

Association between Regimen Composition and Treatment Response in Patients with Multidrug-Resistant Tuberculosis: A Prospective Cohort Study

BACKGROUND

For treating multidrug-resistant tuberculosis (MDR TB), the World Health Organization (WHO) recommends a regimen of at least four second-line drugs that are likely to be effective as well as pyrazinamide. WHO guidelines indicate only marginal benefit for regimens based directly on drug susceptibility testing (DST) results. Recent evidence from isolated cohorts suggests that regimens containing more drugs may be beneficial, and that DST results are predictive of regimen effectiveness. The objective of our study was to gain insight into how regimen design affects treatment response by analyzing the association between time to sputum culture conversion and both the number of potentially effective drugs included in a regimen and the DST results of the drugs in the regimen.

METHODS AND FINDINGS

We analyzed data from the Preserving Effective Tuberculosis Treatment Study (PETTS), a prospective observational study of 1,659 adults treated for MDR TB during 2005-2010 in nine countries: Estonia, Latvia, Peru, Philippines, Russian Federation, South Africa, South Korea, Thailand, and Taiwan. For all patients, monthly sputum samples were collected, and DST was performed on baseline isolates at the US Centers for Disease Control and Prevention. We included 1,137 patients in our analysis based on their having known baseline DST results for at least fluoroquinolones and second-line injectable drugs, and not having extensively drug-resistant TB. These patients were followed for a median of 20 mo (interquartile range 16-23 mo) after MDR TB treatment initiation. The primary outcome of interest was initial sputum culture conversion. We used Cox proportional hazards regression, stratifying by country to control for setting-associated confounders, and adjusting for the number of drugs to which patients' baseline isolates were resistant, baseline resistance pattern, previous treatment history, sputum smear result, and extent of disease on chest radiograph. In multivariable analysis, receiving an average of at least six potentially effective drugs (defined as drugs without a DST result indicating resistance) per day was associated with a 36% greater likelihood of sputum culture conversion than receiving an average of at least five but fewer than six potentially effective drugs per day (adjusted hazard ratio [aHR] 1.36, 95% CI 1.09-1.69). Inclusion of pyrazinamide (aHR 2.00, 95% CI 1.65-2.41) or more drugs to which baseline DST indicated susceptibility (aHR 1.65, 95% CI 1.48-1.84, per drug) in regimens was associated with greater increases in the likelihood of sputum culture conversion than including more drugs to which baseline DST indicated resistance (aHR 1.33, 95% CI 1.18-1.51, per drug). Including in the regimen more drugs for which DST was not performed was beneficial only if a minimum of three effective drugs was present in the regimen (aHR 1.39, 95% CI 1.09-1.76, per drug when three effective drugs present in regimen). The main limitation of this analysis is that it is based on observational data, not a randomized trial, and drug regimens varied across sites. However, PETTS was a uniquely large and rigorous observational study in terms of both the number of patients enrolled and the standardization of laboratory testing. Other limitations include the assumption of equivalent efficacy across drugs in a category, incomplete data on adherence, and the fact that the analysis considers only initial sputum culture conversion, not reversion or long-term relapse.

CONCLUSIONS

MDR TB regimens including more potentially effective drugs than the minimum of five currently recommended by WHO may encourage improved response to treatment in patients with MDR TB. Rapid access to high-quality DST results could facilitate the design of more effective individualized regimens. Randomized controlled trials are necessary to confirm whether individualized regimens with more than five drugs can indeed achieve better cure rates than current recommended regimens.

The challenge of managing extensively drug-resistant tuberculosis at a referral hospital in the state of São Paulo, Brazil: a report of three cases

Here, we report the cases of three patients diagnosed with extensively drug-resistant tuberculosis and admitted to a referral hospital in the state of São Paulo, Brazil, showing the clinical and radiological evolution, as well as laboratory test results, over a one-year period. Treatment was based on the World Health Organization guidelines, with the inclusion of a new proposal for the use of a combination of antituberculosis drugs (imipenem and linezolid). In the cases studied, we show the challenge of creating an acceptable, effective treatment regimen including drugs that are more toxic, are more expensive, and are administered for longer periods. We also show that treatment costs are significantly higher for such patients, which could have an impact on health care systems, even after hospital discharge. We highlight the fact that in extreme cases, such as those reported here, hospitalization at a referral center seems to be the most effective strategy for providing appropriate treatment and increasing the chance of cure. In conclusion, health professionals and governments must make every effort to prevent cases of multidrug-resistant and extensively drug-resistant tuberculosis.

Multidrug-Resistant Tuberculosis Treatment Outcomes in Relation to Treatment and Initial Versus Acquired Second-Line Drug Resistance

BACKGROUND

Resistance to second-line drugs develops during treatment of multidrug-resistant (MDR) tuberculosis, but the impact on treatment outcome has not been determined.

METHODS

Patients with MDR tuberculosis starting second-line drug treatment were enrolled in a prospective cohort study. Sputum cultures were analyzed at a central reference laboratory. We compared subjects with successful and poor treatment outcomes in terms of (1) initial and acquired resistance to fluoroquinolones and second-line injectable drugs (SLIs) and (2) treatment regimens.

RESULTS

Of 1244 patients with MDR tuberculosis, 973 (78.2%) had known outcomes and 232 (18.6%) were lost to follow-up. Among those with known outcomes, treatment succeeded in 85.8% with plain MDR tuberculosis, 69.7% with initial resistance to either a fluoroquinolone or an SLI, 37.5% with acquired resistance to a fluoroquinolone or SLI, 29.3% with initial and 13.0% with acquired extensively drug-resistant tuberculosis (P < .001 for trend). In contrast, among those with known outcomes, treatment success increased stepwise from 41.6% to 92.3% as the number of drugs proven effective increased from ≤1 to ≥5 (P < .001 for trend), while acquired drug resistance decreased from 12% to 16% range, depending on the drug, down to 0%-2% (P < .001 for trend). In multivariable analysis, the adjusted odds of treatment success decreased 0.62-fold (95% confidence interval, .56-.69) for each increment in drug resistance and increased 2.1-fold (1.40-3.18) for each additional effective drug, controlling for differences between programs and patients. Specific treatment, patient, and program variables were also associated with treatment outcome.

CONCLUSIONS

Increasing drug resistance was associated in a logical stepwise manner with poor treatment outcomes. Acquired resistance was worse than initial resistance to the same drugs. Increasing numbers of effective drugs, specific drugs, and specific program characteristics were associated with better outcomes and less acquired resistance.

The Race Is On To Shorten the Turnaround Time for Diagnosis of Multidrug-Resistant Tuberculosis

To realize the most benefit from multidrug-resistant tuberculosis (MDR-TB) screening, all nucleic acid amplification test (NAAT)-positive respiratory specimens should be universally tested. Once an MDR-TB diagnosis is established, additional testing is warranted to provide details about the detected mutations. The lab-on-chip technology described by A. M. Cabibbe et al. (J Clin Microbiol 53:3876-3880, 2015, http://dx.doi.org/10.1128/JCM.01824-15) potentially provides this much needed information.

Medical Management of Drug-Resistant Tuberculosis

Drug-resistant tuberculosis (TB) is still a major threat worldwide. However, recent scientific advances in diagnostic and therapeutic tools have improved the management of drug-resistant TB. The development of rapid molecular testing methods allows for the early detection of drug resistance and prompt initiation of an appropriate treatment. In addition, there has been growing supportive evidence for shorter treatment regimens in multidrug-resistant TB; and for the first time in over 50 years, new anti-TB drugs have been developed. The World Health Organization has recently revised their guidelines, primarily based on evidence from a meta-analysis of individual patient data (n=9,153) derived from 32 observational studies, and outlined the recommended combination and correct use of available anti-TB drugs. This review summarizes the updated guidelines with a focus on the medical management of drug-resistant TB.

Counting pyrazinamide in regimens for multidrug-resistant tuberculosis

RATIONALE

For treatment of multidrug-resistant tuberculosis, World Health Organization (WHO) guidelines recommend four likely effective drugs plus pyrazinamide (PZA), irrespective of the likely effectiveness of PZA in an individual patient. Whether this regimen should be supplemented in the absence of likely PZA effectiveness is an open question.

OBJECTIVES

The objectives of this study were to examine (1) whether individuals receiving four likely effective drugs (based on documented susceptibility or no prior exposure) experienced higher mortality during the intensive phase of treatment than those receiving five likely effective drugs and (2) whether the WHO-recommended regimen (four likely effective drugs plus PZA) may be compromised in individuals in whom PZA is not likely effective.

METHODS

Among 668 patients, we compared the hazard of death across regimen groups characterized by the number of likely effective drugs and whether pyrazinamide was one of the likely effective drugs.

MEASUREMENTS AND MAIN RESULTS

Relative to five likely effective drugs, regimens of four likely effective drugs and the WHO-recommended regimen used in individuals in whom PZA was not likely effective were associated with higher mortality rates (respectively, adjusted hazard ratio [HR], 2.87; 95% confidence interval [CI], 1.35-6.09 and adjusted HR, 2.76; 95% CI, 0.92-8.27). The mortality rate for a regimen of five likely effective drugs with likely effective PZA was similar to that for the regimen of five likely effective drugs without PZA (HR, 1.00; 95% CI, 0.12-8.00).

CONCLUSIONS

Mortality may be reduced by the inclusion of five likely effective drugs, including an injectable, during the intensive phase of treatment. If PZA is unlikely to be effective in an individual patient, these results suggest adding a different, likely effective drug.

Quantitative drug-susceptibility in patients treated for multidrug-resistant tuberculosis in Bangladesh: implications for regimen choice

Background

Multidrug-resistant tuberculosis (MDR-TB) treatment in Bangladesh is empiric or based on qualitative drug-susceptibility testing (DST) by comparative growth in culture media with and without a single drug concentration.

Methods

Adult patients were enrolled throughout Bangladesh during the period of 2011–2013 at MDR-TB treatment initiation. Quantitative DST by minimum inhibitory concentration (MIC) testing for 12 first and second-line anti-TB drugs was compared to pretreatment clinical characteristics and treatment outcomes. MIC values at or one dilution lower than the resistance breakpoint used for qualitative DST were categorized as borderline susceptible, and MIC values one or two dilutions greater as borderline resistant.

Results

Seventy-four patients were enrolled with a mean age of 35 ±15 years, and 51 (69%) were men. Of the rifampin isolates with MIC >1.0 μg/ml, 12 (19%) were fully susceptible or borderline susceptible to rifabutin (MIC ≤0.5 μg/ml). Amikacin was fully susceptible in 73 isolates (99%), but kanamycin in only 54 (75%) (p<0.001). Ofloxacin was borderline susceptible in 64%, and fully susceptible in only 14 (19%) compared to 60 (81%) of isolates fully susceptible for moxifloxacin (p<0.001). Kanamycin non-susceptibility and receipt of the WHO Category IV regimen trended with interim treatment failure: adjusted odd ratios respectively of 5.4 [95% CI 0.82–36.2] (p = 0.08) and 7.2 [0.64–80.7] (p = 0.11).

Conclusions

Quantitative MIC testing could impact MDR-TB regimen choice in Bangladesh. Comparative trials of higher dose or later generation fluoroquinolone, within class change from kanamycin to amikacin, and inclusion of rifabutin appear warranted.

Delamanid when other anti-tuberculosis-treatment regimens failed due to resistance or tolerability

INTRODUCTION

The limited availability of effective drugs causes difficulties in the management of multidrug-resistant tuberculosis (MDR-TB) and novel therapeutic agents are needed. Delamanid , a new nitro-hydro-imidazooxazole derivative, inhibits mycolic acid synthesis. This review covers the efficacy and safety of delamanid for MDR-TB.

AREA COVERED

This paper reviews the pharmacological profile of delamanid and the results of clinical trials evaluating its efficacy for treating MDR-TB in combination with other anti-TB drugs. The drug's safety and tolerability profiles are also considered.

EXPERT OPINION

Delamanid showed potent activity against drug-susceptible and -resistant Mycobacterium tuberculosis in both in vitro and in vivo studies. In clinical trials, the drug showed significant early bactericidal activity in pulmonary TB patients, and increased culture conversion after 2 months of treatment in combination with an optimized background regimen in MDR-TB patients. In addition, decreased mortality was observed in MDR-TB patients who received > 6 months of delamanid treatment. The drug was generally tolerable, but QT prolongation should be monitored carefully using electrocardiograms and potassium levels. Therefore, delamanid could be used as part of an appropriate combination regimen for pulmonary MDR-TB in adult patients when an effective treatment regimen cannot otherwise be composed for reasons of resistance or tolerability.

Time to culture conversion and regimen composition in multidrug-resistant tuberculosis treatment

Sputum cultures are an important tool in monitoring the response to tuberculosis treatment, especially in multidrug-resistant tuberculosis. There has, however, been little study of the effect of treatment regimen composition on culture conversion. Well-designed clinical trials of new anti-tuberculosis drugs require this information to establish optimized background regimens for comparison. We conducted a retrospective cohort study to assess whether the use of an aggressive multidrug-resistant tuberculosis regimen was associated with more rapid sputum culture conversion. We conducted Cox proportional-hazards analyses to examine the relationship between receipt of an aggressive regimen for the 14 prior consecutive days and sputum culture conversion. Sputum culture conversion was achieved in 519 (87.7%) of the 592 patients studied. Among patients who had sputum culture conversion, the median time to conversion was 59 days (IQR: 31–92). In 480 patients (92.5% of those with conversion), conversion occurred within the first six months of treatment. Exposure to an aggressive regimen was independently associated with sputum culture conversion during the first six months of treatment (HR: 1.36; 95% CI: 1.10, 1.69). Infection with human immunodeficiency virus (HR 3.36; 95% CI: 1.47, 7.72) and receiving less exposure to tuberculosis treatment prior to the individualized multidrug-resistant tuberculosis regimen (HR: 1.58; 95% CI: 1.28, 1.95) were also independently positively associated with conversion. Tachycardia (HR: 0.77; 95% CI: 0.61, 0.98) and respiratory difficulty (HR: 0.78; 95% CI: 0.62, 0.97) were independently associated with a lower rate of conversion. This study is the first demonstrating that the composition of the multidrug-resistant tuberculosis treatment regimen influences the time to culture conversion. These results support the use of an aggressive regimen as the optimized background regimen in trials of new anti-TB drugs.