Second-line Tuberculosis Drugs Research Articles

Development of new anti-tuberculosis drugs: the strategy of unconventional microbial culture and silencing gene activation

Tuberculosis (TB), caused by Mycobacterium tuberculosis, has become a major human infectious disease. The existing first-line and second-line TB drugs have poor treatment outcomes in patients with MDR-TB and XDR-TB. There is an urgent need for new and better drugs to treat tuberculosis due to lengthy and complex treatment regimens and a rising problem of drug resistance. Microbial-derived natural products have revealed enormous reservoirs of as yet untapped lead compounds. In this review, we discuss the strategies that have been developed in bacteria and fungi to isolation of non-culturable microorganisms and activation of silent biosynthetic gene clusters involved in the study of microbial-derived natural products. This review also highlights recent advances in microbial-derived natural products with anti-tuberculosis activity using these methods.

Rational Design of Biosafety Level 2-Approved, Multidrug-Resistant Strains of Mycobacterium tuberculosis through Nutrient Auxotrophy.

ABSTRACTMultidrug-resistant (MDR) tuberculosis, defined as tuberculosis resistant to the two first-line drugs isoniazid and rifampin, poses a serious problem for global tuberculosis control strategies. Lack of a safe and convenient model organism hampers progress in combating the spread of MDR strains of Mycobacterium tuberculosis. We reasoned that auxotrophic MDR mutants of M. tuberculosis would provide a safe means for studying MDR M. tuberculosis without the need for a biosafety level 3 (BSL3) laboratory. Two different sets of triple auxotrophic mutants of M. tuberculosis were generated, which were auxotrophic for the nutrients leucine, pantothenate, and arginine or for leucine, pantothenate, and methionine. These triple auxotrophic strains retained their acid-fastness, their ability to generate both a drug persistence phenotype and drug-resistant mutants, and their susceptibility to plaque-forming mycobacterial phages. MDR triple auxotrophic mutants were obtained in a two-step fashion, selecting first for solely isoniazid-resistant or rifampin-resistant mutants. Interestingly, selection for isoniazid-resistant mutants of the methionine auxotroph generated isolates with single point mutations in katG, which encodes an isoniazid-activating enzyme, whereas similar selection using the arginine auxotroph yielded isoniazid-resistant mutants with large deletions in the chromosomal region containing katG. These M. tuberculosis MDR strains were readily sterilized by second-line tuberculosis drugs and failed to kill immunocompromised mice. These strains provide attractive candidates for M. tuberculosis biology studies and drug screening outside the BSL3 facility.

Molecular characterization of mutations associated with resistance to second-line tuberculosis drug among multidrug-resistant tuberculosis patients from high prevalence tuberculosis city in Morocco

BackgroundThe emergence of extensively drug-resistant tuberculosis (XDR-TB) has raised public health concern for global TB control. Although multi drug-resistant tuberculosis (MDR- TB) prevalence and associated genetic mutations in Morocco are well documented, scarce information on XDR TB is available. Hence, the evaluation of pre-XDR and XDR prevalence, as well as the mutation status of gyrA, gyrB, rrs, tlyA genes and eis promoter region, associated with resistance to second line drugs, is of great value for better management of M/XDR TB in Morocco.MethodsDrug susceptibility testing (DST) was performed by the proportional method for first line drugs, and then the selected MDR isolates were tested for second line drugs (Ofloxacin, Kanamycin, Amikacin and Capreomycin). Along with DST, all samples were subjected to rpoB, katG and p-inhA mutation analysis by PCR and DNA sequencing. MDR isolates as well as 30 pan-susceptible strains were subjected to PCR and DNA sequencing of gyrA, gyrB, rrs, tlyA genes and eis promoter, associated with resistance to fluoroquinolones and injectable drugs.ResultsAmong the 703 analysed strains, 12.8% were MDR; Ser531Leu and Ser315Thr being the most common recorded mutations within rpoB and katG genes associated with RIF and INH resistance respectively. Drug susceptibility testing for second line drugs showed that among the 90 MDR strains, 22.2% (20/90) were resistant to OFX, 2.22% (2/90) to KAN, 3.33% (3/90) to AMK and 1.11% (1/90) to CAP. Genotypic analysis revealed that 19 MDR strains harbored mutations in the gyrA gene; the most recorded mutation being Asp91Ala accounting for 47.6% (10/21), and 2 isolates harbored mutations in the promoter region of eis gene. No mutation was found in gyrB, rrs and tlyA genes. Moreover, none of the pan-susceptible isolates displayed mutations in targeted genes.ConclusionMost of mutations associated with SLD resistance occurred in gyrA gene (codons 90-94) and eis promoter region. These findings highlight the impact of mutations in gyrA on the development of fluroquinolones resistance and provide the first estimates of the proportion of pre-XDR-TB among MDR-TB cases in Morocco.

In Vitro Susceptibility of Mycobacterium tuberculosis to Amikacin, Kanamycin, and Capreomycin.

Amikacin, kanamycin, and capreomycin are among the most important second-line drugs for multidrug-resistant tuberculosis. Although amikacin and kanamycin are administered at the same dose and show the same pharmacokinetics, they have different WHO breakpoints, suggesting that the two drugs have different MICs. The aim of this study was to investigate possible differences in MICs between the aminoglycosides and capreomycin. Using the direct concentration method, a range of concentrations of amikacin, kanamycin, and capreomycin (0.25, 0.50, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, and 64.0 mg/liter) were tested against 57 clinical Mycobacterium tuberculosis strains. The 7H10 agar plates were examined for mycobacterial growth after 14 days. At 2 mg/liter, 48 strains (84%) were inhibited by amikacin and only 5 strains (9%) were inhibited by kanamycin (P < 0.05, Wilcoxon signed-rank test). The median MICs of amikacin, kanamycin, and capreomycin were 2, 4, and 8 mg/liter, respectively. No difference in amikacin, kanamycin, and capreomycin MIC distributions was observed between multidrug-resistant strains and fully susceptible strains. The results indicate that amikacin is more active than kanamycin and capreomycin against M. tuberculosis with the absolute concentration method. Determination of the impact of this difference on clinical outcomes in daily practice requires a prospective study, including pharmacokinetic and pharmacodynamic evaluations.

Social and Molecular Networks Reveal Dynamics Behind the Rising Incidence of Extensively Drug-resistant Tuberculosis.

Tuberculosis (TB)2 is a significant cause of morbidity and mortality worldwide, particularly in people with HIV coinfection. Although TB is typically a treatable disease, cases of multidrug resistant TB (MDR-TB) that are resistant to the first-line drugs rifampin and isoniazid have emerged in recent years, presumably due to inadequate treatment or subtherapeutic drug concentrations. Another worrisome trend is the emergence of a subset of MDR-TB known as extensively drug-resistant (XDR)-TB, which is resistant to at least 4 first- and second-line drugs for TB. Cases of XDR-TB require complicated toxic treatment regimens that achieve a cure rate of <40%. The World Health Organization estimates that 500000 cases of MDR-TB occur each year worldwide, with about 10% of these classified as XDR-TB. Over 100 …

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

Mortality among HIV patients with tuberculosis (TB) remains high in Eastern Europe (EE), but details of TB and HIV management remain scarce. In this prospective study, we describe the TB treatment regimens of patients with multi-drug resistant (MDR) TB and use of antiretroviral therapy (ART). 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%. 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.

Reducing stock-outs of essential tuberculosis medicines: a system dynamics modelling approach to supply chain management.

The under-performance of supply chains presents a significant hindrance to disease control in developing countries. Stock-outs of essential medicines lead to treatment interruption which can force changes in patient drug regimens, drive drug resistance and increase mortality. This study is one of few to quantitatively evaluate the effectiveness of supply chain policies in reducing shortages and costs. This study develops a systems dynamics simulation model of the downstream supply chain for amikacin, a second-line tuberculosis drug using 10 years of South African data. We evaluate current supply chain performance in terms of reliability, responsiveness and agility, following the widely-used Supply Chain Operation Reference framework. We simulate 141 scenarios that represent different combinations of supplier characteristics, inventory management strategies and demand forecasting methods to identify the Pareto optimal set of management policies that jointly minimize the number of shortages and total cost. Despite long supplier lead times and unpredictable demand, the amikacin supply chain is 98% reliable and agile enough to accommodate a 20% increase in demand without a shortage. However, this is accomplished by overstocking amikacin by 167%, which incurs high holding costs. The responsiveness of suppliers is low: only 57% of orders are delivered to the central provincial drug depot within one month. We identify three Pareto optimal safety stock management policies. Short supplier lead time can produce Pareto optimal outcomes even in the absence of other optimal policies. This study produces concrete, actionable guidelines to cost-effectively reduce stock-outs by implementing optimal supply chain policies. Preferentially selecting drug suppliers with short lead times accommodates unexpected changes in demand. Optimal supply chain management should be an essential component of national policy to reduce the mortality rate.

A study of clinical profile of cases of MDR-TB and evaluation of challenges faced in initiation of second line Anti tuberculosis treatment for MDR-TB cases admitted in drug resistance tuberculosis center

ObjectivesTo study the clinical profile of cases, evaluation of comorbidities and problems encountered in initiation of second-line drugs for multidrug-resistant tuberculosis (MDR-TB) patients. MethodologyA prospective observational study was conducted on MDR patients admitted in drug resistance tuberculosis (DRTB) center of RDGMC Surasa Ujjain, a rural medical college, over a span of one year. ResultsOut of 130 admitted cases, majority (30%) were between 31 and 40 years of age. Males were predominant (70%). Females were significantly younger compared to males (p=0.00308). Most patients (83.8%) were underweight (body mass index (BMI)<18.5kg/m2). According to MDR-TB suspect criteria, majority were defaulter cases (39.23%). The anemia was the most common comorbidity (73.84%) among the study group followed by diabetes mellitus (9.23%), chronic obstructive pulmonary disease (COPD) (9.23%), 10 (7.69) asthma, 10 (7.69%) thyroid disease 9 (6.92%) followed by respiratory insufficiency 4 (3%), HIV 2 (1.5%), deep venous thrombosis (DVT) 2 (1.5%), renal failure 2 (1.5%), and hepatic failure 1 (0.76%). Majority had minimal lesion – 57 (43.8%), moderate – 38 (29.2%), and moderate advanced – 23 (17.7%) while far advanced was noted on X-rays in 12 (9.2%). A total of 91 (70%) cases had non-cavitary lesions and 39 (30%) had cavitary lesions, of which 27 were unilateral and 12 were bilateral. ConclusionThe males were predominant in our study however females were affected at a younger age compared to the males. Most of the patients had taken Anti tuberculosis treatment (ATT) from Revised National Tuberculosis Control Program (RNTCP) in which defaulter and relapse were the major contributors of MDR-TB cases in our study. Radiological extent of lesions of these patients was less than expectation. Management of comorbidities is essential for compliance to treatment. It necessitates prolonged hospitalization and requires frequent follow-up in the DRTB center.

The production and sales of anti-tuberculosis drugs in China.

BackgroundTuberculosis (TB) is a major infectious disease globally. Adequate and proper use of anti-TB drugs is essential for TB control. This study aims to study China’s production capacity and sales situation of anti-TB drugs, and to further discuss the potential for China to contribute to global TB control.MethodsThe production data of anti-TB drugs in China from 2011 to 2013 and the sales data from 2010 to 2014 were extracted from Ministry of Industry and Information Technology database of China and IMS Health database, respectively. The number of drugs was standardized to the molecular level of the key components before calculating. All data were described and analyzed by Microsoft Excel.ResultsFirst-line drugs were the majority in both sales (89.5 %) and production (92.3 %) of anti-TB drugs in China. The production of rifampicin held the majority share in active pharmaceutical ingredients (APIs) and finished products, whilst ethambutol and pyrazinamide were the top two sales in finished products. Fixed-dose combinations only held small percentages in total production and sales weight, though a slight increase was observed. The production and sales of streptomycin showed a tendency of decrease after 2012. The trends and proportion of different anti-TB drugs were similar in production and sales, however, the production weight was much larger than that of sales, especially for rifampicin and isoniazid.ConclusionsFirst-line drugs were the predominant medicine produced and used in China. While the low production and sales of the second-line TB drugs and FDCs rose concerns for the treatment of multiple drug resistant TB. The redundant production amount, as well as the prompt influence of national policy on drug production and sales, indicated the potential for China to better contribute to global TB control.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0184-z) contains supplementary material, which is available to authorized users.

Genetic Determinants of Drug Resistance in Mycobacterium tuberculosis and Their Diagnostic Value.

The development of molecular diagnostics that detect both the presence of Mycobacterium tuberculosis in clinical samples and drug resistance-conferring mutations promises to revolutionize patient care and interrupt transmission by ensuring early diagnosis. However, these tools require the identification of genetic determinants of resistance to the full range of antituberculosis drugs. To determine the optimal molecular approach needed, we sought to create a comprehensive catalog of resistance mutations and assess their sensitivity and specificity in diagnosing drug resistance. We developed and validated molecular inversion probes for DNA capture and deep sequencing of 28 drug-resistance loci in M. tuberculosis. We used the probes for targeted sequencing of a geographically diverse set of 1,397 clinical M. tuberculosis isolates with known drug resistance phenotypes. We identified a minimal set of mutations to predict resistance to first- and second-line antituberculosis drugs and validated our predictions in an independent dataset. We constructed and piloted a web-based database that provides public access to the sequence data and prediction tool. The predicted resistance to rifampicin and isoniazid exceeded 90% sensitivity and specificity but was lower for other drugs. The number of mutations needed to diagnose resistance is large, and for the 13 drugs studied it was 238 across 18 genetic loci. These data suggest that a comprehensive M. tuberculosis drug resistance diagnostic will need to allow for a high dimension of mutation detection. They also support the hypothesis that currently unknown genetic determinants, potentially discoverable by whole-genome sequencing, encode resistance to second-line tuberculosis drugs.

Tuberculosis Treatment Outcome and Drug Resistance in Lambaréné, Gabon: A Prospective Cohort Study.

Despite overall global progress in tuberculosis (TB) control, TB remains one of the deadliest communicable diseases. This study prospectively assessed TB epidemiology in Lambaréné, Gabon, a Central African country ranking 10th in terms of TB incidence rate in the 2014 World Health Organization TB report. In Lambaréné, between 2012 and 2014, 201 adult and pediatric TB patients were enrolled and followed up; 66% had bacteriologically confirmed TB and 95% had pulmonary TB. The human immunodeficiency virus (HIV) coinfection rate was 42% in adults and 16% in children. Mycobacterium tuberculosis and Mycobacterium africanum were identified in 82% and 16% of 108 culture-confirmed TB cases, respectively. Isoniazid (INH) and streptomycin yielded the highest resistance rates (13% and 12%, respectively). The multidrug resistant TB (MDR-TB) rate was 4/91 (4%) and 4/13 (31%) in new and retreatment TB cases, respectively. Treatment success was achieved in 53% of patients. In TB/HIV coinfected patients, mortality rate was 25%. In this setting, TB epidemiology is characterized by a high rate of TB/HIV coinfection and low treatment success rates. MDR-TB is a major public health concern; the need to step-up in-country diagnostic capacity for culture and drug susceptibility testing as well as access to second-line TB drugs urgently requires action.

Prevalence of resistance to second-line tuberculosis drug among multidrug-resistant tuberculosis patients in VietNam, 2011.

IntroductionExtensively drug-resistant tuberculosis (XDR-TB) represents an emerging public health problem worldwide. According to the World Health Organization, an estimated 9.7% of multidrug-resistant TB (MDR-TB) cases are defined as XDR-TB globally. The objective of this study was to determine the prevalence of drug resistance to second-line TB drugs among MDR-TB cases detected in the Fourth National Anti-Tuberculosis Drug Resistance Survey in Viet Nam.MethodsEighty clusters of TB cases were selected using a probability-proportion-to-size approach. To identify MDR-TB cases, drug susceptibility testing (DST) was performed for the four major first-line TB drugs. DST of second-line drugs (ofloxacin, amikacin, kanamycin, capreomycin) was performed on isolates from MDR-TB cases to identify pre-XDR and XDR cases.ResultsA total of 1629 smear-positive TB cases were eligible for culture and DST. Of those, DST results for first-line drugs were available for 1312 cases, and 91 (6.9%) had MDR-TB. Second-line DST results were available for 84 of these cases. Of those, 15 cases (17.9%) had ofloxacin resistance and 6.0% were resistant to kanamycin and capreomycin. Five MDR-TB cases (6.0%) met the criteria of XDR-TB.ConclusionThis survey provides the first estimates of the proportion of XDR-TB among MDR-TB cases in Viet Nam and provides important information for local policies regarding second-line DST. Local policies and programmes that are geared towards TB prevention, early diagnosis and treatment with effective regimens are of high importance.

Preventive use of a hepatoprotectant against anti-tuberculosis drug-induced liver injury: A randomized controlled trial.

Hepatoprotectants are routinely prescribed in China to prevent anti-tuberculosis drug-induced liver injury (ATLI). However, their biological mechanisms have not yet been clearly demonstrated. This study aims to evaluate the preventive effects of Silybum marianum against drug-induced liver injury among tuberculosis patients and to provide clinical guidelines for tuberculosis management in China. A randomized controlled trial was performed in Jiangsu, China. Tuberculosis patients were randomly allocated to the experimental group (anti-tuberculosis therapy plus S. marianum capsule) or the control group (anti-tuberculosis therapy plus vitamin C tablet). The primary outcomes were the occurrence of probable and possible ATLI, the peak aspartate aminotransferase/alanine aminotransferase ratio and the maximum altered alkaline phosphatase or gamma-glutamyl transferase. The final analysis comprised 183 cases in the experiment group and 187 cases in the control group. The risk of developing probable ATLI was not significantly different between the two groups. During the follow-up period, 43.72% of cases in the experiment group and 35.83% of cases in the control group were determined to have possible ATLI (relative risk = 1.23, 95% confidence interval: 0.94-1.54). When using a more strict definition of possible ATLI, the adjusted relative risk (95% confidence interval) was 1.76 (1.14-2.56). The risks of adverse drug reactions, prolonged treatment length, taking second-line tuberculosis drugs, and the clearance of tuberculosis bacteria were similar between the two groups. No significant preventive effect of silymarin was found for either lowering the risk of liver injury or boosting the positive outcomes. Worse, we even found a potential risk of liver damage caused by the hepatoprotectant.

Pharmacokinetics of ertapenem in patients with multidrug-resistant tuberculosis.

Treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) is becoming more challenging because of increased levels of drug resistance against second-line TB drugs. One promising group of antimicrobial drugs is carbapenems. Ertapenem is an attractive carbapenem for the treatment of MDR- and XDR-TB because its relatively long half-life enables once-daily dosing.A retrospective study was performed for all patients with suspected MDR-TB at the Tuberculosis Center Beatrixoord of the University Medical Center Groningen (Haren, the Netherlands) who received ertapenem as part of their treatment regimen between December 1, 2010 and March 1, 2013. Safety and pharmacokinetics were evaluated.18 patients were treated with 1000 mg ertapenem for a mean (range) of 77 (5-210) days. Sputum smear and culture were converted in all patients. Drug exposure was evaluated in 12 patients. The mean (range) area under the concentration-time curve up to 24 h was 544.9 (309-1130) h·mg·L(-1) The mean (range) maximum observed plasma concentration was 127.5 (73.9-277.9) mg·L(-1)In general, ertapenem treatment was well tolerated during MDR-TB treatment and showed a favourable pharmacokinetic/pharmacodynamic profile in MDR-TB patients. We conclude that ertapenem is a highly promising drug for the treatment of MDR-TB that warrants further investigation.

Efflux Pump Mediated Second-Line Tuberculosis Drug Resistance

The burden and spread of drug-resistant tuberculosis disease is a major public health problem worldwide. The causative agent, Mycobacterium tuberculosis uses several mechanisms to counteract therapy through drugresistance. A major and most common mechanism of drug-resistance is mediated through target mutations. Efflux pumps are emerging as potential agents of drug-resistance and treatment failure. In this review we explore the origin and principles of efflux pump-mediated resistance and determine their impact on second-line drugs used against extensively drug resistant tuberculosis. Inhibition of efflux pumps as a therapeutic intervention is also discussed.

Paediatric formulations of second-line anti-tuberculosis medications: challenges and considerations.

There is a growing number of children worldwide accessing second-line anti-tuberculosis drugs for multidrug-resistant tuberculosis (TB); however, there are very few child-friendly formulations. For paediatric use, dispersible tablets offer distinct advantages over liquid formulations and other approaches. This is particularly relevant for TB, where stability, long shelf-life and reduced manufacturing, transport and storage costs are all critical to ensuring that drugs are accessible and affordable. In addition, fixed-dose combinations that reduce the pill burden and provide adequate taste masking may promote long-term adherence to anti-tuberculosis treatment and prevention regimens likely to last many months in children. Partial adherence may result in treatment failure and the further selection and spread of resistant mycobacteria. Unfortunately, no second-line TB paediatric drugs exist in dispersible formulations. We discuss here the main obstacles to developing such tablets and present strategies for overcoming them. We also advocate for timely anticipation of paediatric use when new TB drugs are being developed, and for the development of child-friendly anti-tuberculosis formulations in general.

Inhibitory potential of tuberculosis drugs on ATP-binding cassette drug transporters

Multiple-drug therapy for tuberculosis (TB) and TB-associated co-morbidity increase the likelihood of drug-drug interactions (DDIs). Inhibition of membrane transporters is an important mechanism underlying DDIs. In this study, we assessed the in vitro inhibitory potential of currently used first and second-line TB drugs and of proposed mycobacterial efflux pump inhibitors (EPIs) on the major ABC transporters relevant to drug transport, namely P-gp, BCRP, BSEP and MRP1-5. Membrane vesicles isolated from transporter-overexpressing HEK293 cells were used to study the inhibitory action of TB drugs and EPIs on the transport of model substrates [(3)H]-NMQ (P-gp); [(3)H]-E1S (BCRP); [(3)H]-TCA (BSEP); [(3)H]-E217βG (MRP1, 3 and 4) and [(3)H]-MTX (MRP2 and 5). A strong inhibition (IC50 value <15 μM) was observed for clofazimine (P-gp, BCRP and MRP1), thioridazine (BCRP), timcodar (P-gp, BSEP and MRP1) and SQ109 (P-gp and BCRP). Rifampicin inhibited all transporters, but less potently. Co-administration of clofazimine, thioridazine, timcodar, SQ109 and possibly rifampicin with drugs that are substrates for the inhibited transporters may lead to DDIs. The mycobacterial EPIs potently inhibited a wider range of human ABC transporters than previously reported. These vesicular transport data are especially valuable considering the current emphasis on development of TB drug regimens.

The Global Drug Facility as an intervention in the market for tuberculosis drugs.

ObjectiveTo investigate funding for the Global Drug Facility since 2001 and to analyse the facility’s influence on the price of high-quality tuberculosis drugs.MethodsData on the price of tuberculosis drugs were obtained from the Global Drug Facility for 2001 to 2012 and, for the private sector in 15 countries, from IMS Health for 2002 to 2012. Data on funding of the facility were also collected.FindingsQuality-assured tuberculosis drugs supplied by the Global Drug Facility were generally priced lower than drugs purchased in the private sector. In 2012, just three manufacturers accounted for 29.9 million United Stated dollars (US$) of US$ 44.5 million by value of first-line drugs supplied. The Global Fund to Fight AIDS, Tuberculosis and Malaria provided 73% (US$ 32.5 million of US$ 44.5 million) and 89% (US$ 57.8 million of US $65.2 million) of funds for first- and second-line drugs, respectively. Between 2010 and 2012, the facility’s market share of second-line tuberculosis drugs increased from 26.1% to 42.9%, while prices decreased by as much as 24% (from US$ 1231 to US$ 939). Conversely, the facility’s market share of first-line drugs fell from 37.2% to 19.2% during this time, while prices increased from US$ 9.53 to US$ 10.2.ConclusionThe price of tuberculosis drugs supplied through the facility was generally less than that on the private market. However, to realize its full potential and meet the needs of more tuberculosis patients, the facility requires more diverse and stable public funding and greater flexibility to participate in the private market.

Limited access to drugs for resistant tuberculosis: a call to action.

Although the rate of new tuberculosis (TB) cases has been falling worldwide, progress toward the targets for diagnosis and treatment of drug-resistant TB is far off-track. In countries with no reliable TB surveillance system, setbacks and progression of TB control is barely reflected and little is known on the situation in the field. Interviews with health professionals in Gabon revealed limited access to first- and second-line TB drugs and important deficiencies in basic TB control. National and international action needs to be taken to meet the global TB control targets.

Treatment outcomes of patients with multidrug-resistant and extensively drug-resistant tuberculosis according to drug susceptibility testing to first- and second-line drugs: an individual patient data meta-analysis.

Individualized treatment for multidrug-resistant (MDR) tuberculosis and extensively drug-resistant (XDR) tuberculosis depends upon reliable and valid drug susceptibility testing (DST) for pyrazinamide, ethambutol, and second-line tuberculosis drugs. However, the reliability of these tests is uncertain, due to unresolved methodological issues. We estimated the association of DST results for pyrazinamide, ethambutol, and second-line drugs with treatment outcomes in patients with MDR tuberculosis and XDR tuberculosis. We conducted an analysis of individual patient data assembled from 31 previously published cohort studies of patients with MDR and XDR tuberculosis. We used data on patients' clinical characteristics including DST results, treatment received, outcomes, and laboratory methods in each center. DST methods and treatment regimens used in different centers varied considerably. Among 8955 analyzed patients, in vitro susceptibility to individual drugs was consistently and significantly associated with higher odds of treatment success (compared with resistance to the drug), if that drug was used in the treatment regimen. Various adjusted and sensitivity analyses suggest that this was not explained by confounding. The adjusted odds of treatment success for ethambutol, pyrazinamide, and the group 4 drugs ranged from 1.7 to 2.3, whereas for second-line injectables and fluoroquinolones, odds ranged from 2.4 to 4.6. DST for ethambutol, pyrazinamide, and second-line tuberculosis drugs appears to provide clinically useful information to guide selection of treatment regimens for MDR and XDR tuberculosis.