Antituberculosis drugs: drug interactions, adverse effects, and use in special situations. Part 2: second line drugs

Antimycobacterial Activity of Solid Lipid Microparticles Loaded with Ursolic Acid and Oleanolic Acid: In Vitro, In Vivo, and Toxicity Assessments

Ursolic acid (UA) and oleanolic acid (OA) are hydrophobic triterpenoid isomers with demonstrated anti-mycobacterial (Mtb) and immune-regulatory properties, although their poor solubility limits clinical use. We report the development of solid lipid microparticles (SLMs) as delivery vehicles for UA and OA and evaluate their anti-Mtb efficacy in vitro and in vivo, as well as their acute toxicity. SLMs measured 0.7-0.89 µM in size, with complete in vitro release of OA and UA at 40 and 32 h, respectively. The minimum inhibitory concentration (MIC) of SLMs loaded with OA and UA was 40 µg/mL SLMs + 20 µg/mL OA + 20 µg/mL UA for drug-sensitive Mtb and 80 µg/mL SLMs + 40 µg/mL OA + 40 µg/mL UA for multidrug-resistant (MDR) Mtb. These SLMs showed an efficient reduction in Mtb burden in infected alveolar macrophages. In a murine model of late-stage progressive MDR-TB, aerosolized delivery of SLMs containing OA and UA via a metered-dose inhaler significantly reduced pulmonary bacterial loads and extended survival. In vivo, acute toxicity studies revealed no mortality or signs of toxicity. These findings demonstrate that SLMs are an optimal delivery system for terpenoids, providing potent in vitro and in vivo anti-TB activity with an excellent safety profile.

Population Pharmacokinetics and Dose Evaluation of Cycloserine among Patients with Multidrug-Resistant Tuberculosis under Standardized Treatment Regimens

Although cycloserine is a recommended drug for the treatment of multidrug-resistant tuberculosis (MDR-TB) according to World Health Organization (WHO), few studies have reported on pharmacokinetics (PK) and/or pharmacodynamics (PD) data of cycloserine in patients with standardized MDR-TB treatment. This study aimed to estimate the population PK parameters for cycloserine and to identify clinically relevant PK/PD thresholds, as well as to evaluate the current recommended dosage. Data from a large cohort with full PK curves was used to develop a population PK model. This model was used to estimate drug exposure in patients with MDR-TB from a multicentre prospective study in China. The classification and regression tree was used to identify the clinically relevant PK/PD thresholds. Probability of target attainment was analyzed to evaluate the currently recommended dosing strategy. Cycloserine was best described by a two-compartment disposition model. A percentage of time concentration above MICs (T>MIC) of 30% and a ratio of area under drug concentration-time curve (AUC0-24h) over MIC of 36 were the valid predictors for 6-month sputum culture conversion and final treatment outcome. Simulations showed that with WHO-recommended doses (500 mg and 750 mg for patients weighing <45 kg and ≥45 kg), the probability of target attainment exceeded 90% at MIC ≤16 mg/L in MGIT for both T>MIC of 30% and AUC0-24h/MIC of 36. New clinically relevant PK/PD thresholds for cycloserine were identified in patients with standardized MDR-TB treatment. WHO-recommended doses were considered adequate for the MGIT MIC distribution in our cohort of Chinese patients with MDR-TB.

Clinical standards for the dosing and management of TB drugs

BACKGROUND: Optimal drug dosing is important to ensure adequate response to treatment, prevent development of drug resistance and reduce drug toxicity. The aim of these clinical standards is to provide guidance on 'best practice´ for dosing and management of TB drugs.METHODS: A panel of 57 global experts in the fields of microbiology, pharmacology and TB care were identified; 51 participated in a Delphi process. A 5-point Likert scale was used to score draft standards. The final document represents the broad consensus and was approved by all participants.RESULTS: Six clinical standards were defined: Standard 1, defining the most appropriate initial dose for TB treatment; Standard 2, identifying patients who may be at risk of sub-optimal drug exposure; Standard 3, identifying patients at risk of developing drug-related toxicity and how best to manage this risk; Standard 4, identifying patients who can benefit from therapeutic drug monitoring (TDM); Standard 5, highlighting education and counselling that should be provided to people initiating TB treatment; and Standard 6, providing essential education for healthcare professionals. In addition, consensus research priorities were identified.CONCLUSION: This is the first consensus-based Clinical Standards for the dosing and management of TB drugs to guide clinicians and programme managers in planning and implementation of locally appropriate measures for optimal person-centred treatment to improve patient care.

In Silico Drug Discovery Strategies Identified ADMET Properties of Decoquinate RMB041 and Its Potential Drug Targets against Mycobacterium tuberculosis

The highly adaptive cellular response of Mycobacterium tuberculosis to various antibiotics and the high costs for clinical trials, hampers the development of novel antimicrobial agents with improved efficacy and safety. Subsequently, in silico drug screening methods are more commonly being used for the discovery and development of drugs, and have been proven useful for predicting the pharmacokinetics, toxicities, and targets, of prospective new antimicrobial agents. In this investigation we used a reversed target fishing approach to determine potential hit targets and their possible interactions between M. tuberculosis and decoquinate RMB041, a propitious new antituberculosis compound. Two of the 13 identified targets, Cyp130 and BlaI, were strongly proposed as optimal drug-targets for dormant M. tuberculosis, of which the first showed the highest comparative binding affinity to decoquinate RMB041. The metabolic pathways associated with the selected target proteins were compared to previously published molecular mechanisms of decoquinate RMB041 against M. tuberculosis, whereby we confirmed disrupted metabolism of proteins, cell wall components, and DNA. We also described the steps within these pathways that are inhibited and elaborated on decoquinate RMB041’s activity against dormant M. tuberculosis. This compound has previously showed promising in vitro safety and good oral bioavailability, which were both supported by this in silico study. The pharmacokinetic properties and toxicity of this compound were predicted and investigated using the online tools pkCSM and SwissADME, and Discovery Studio software, which furthermore supports previous safety and bioavailability characteristics of decoquinate RMB041 for use as an antimycobacterial medication.

IMPORTANCE This article elaborates on the mechanism of action of a novel antibiotic compound against both, active and dormant Mycobacterium tuberculosis and describes its pharmacokinetics (including oral bioavailability and toxicity). Information provided in this article serves useful during the search for drugs that shorten the treatment regimen for Tuberculosis and cause minimal adverse effects.

Effect of Curcumin in Experimental Pulmonary Tuberculosis: Antimycobacterial Activity in the Lungs and Anti-Inflammatory Effect in the Brain

Tuberculosis (TB) is one of the ten leading causes of death worldwide. Patients with TB have been observed to suffer from depression and anxiety linked to social variables. Previous experiments found that the substantial pulmonary inflammation associated with TB causes neuroinflammation, neuronal death, and behavioral impairments in the absence of brain infection. Curcumin (CUR) is a natural product with antioxidant, anti-inflammatory and antibacterial activities. In this work, we evaluated the CUR effect on the growth control of mycobacteria in the lungs and the anti-inflammatory effect in the brain using a model of progressive pulmonary TB in BALB/c mice infected with drug-sensitive mycobacteria (strain H37Rv). The results have shown that CUR decreased lung bacilli load and pneumonia of infected animals. Finally, CUR significantly decreased neuroinflammation (expression of TNFα, IFNγ and IL12) and slightly increased the levels of nuclear factor erythroid 2-related to factor 2 (Nrf2) and the brain-derived neurotrophic factor (BDNF) levels, improving behavioral status. These results suggest that CUR has a bactericidal effect and can control pulmonary mycobacterial infection and reduce neuroinflammation. It seems that CUR has a promising potential as adjuvant therapy in TB treatment.

Design, synthesis and molecular docking studies of imidazole and benzimidazole linked ethionamide derivatives as inhibitors of InhA and antituberculosis agents

To explore effective antituberculosis agents, a new class of imidazoles and benzimidazoles linked ethionamide analogs were designed and synthesized. The elemental analysis, ¹H NMR, ¹³C NMR and mass spectral data were used to characterize all of the novel analogs. In vitro activity against Mycobacterium tuberculosis (Mtb) H37Rv was assessed for all of the target compounds. The hydroxy and nitrile moieties on the imidazole ring, as well as the hydroxy and methoxy groups on the benzimidazole ring connected to the ethionamide side chain, were shown to be advantageous. In our cell viability experiment against the Vero cell line, all of the compounds were non-cytotoxic even at 100 μM. To confirm the powerful analogs target identification, we investigated their in vitro inhibitory action on an M. tuberculosis InhA over-expressing (Mtb InhA-OE) strain, which yielded MICs nearly twice those of the Mtb H37Rv strain. Furthermore, the results of molecular docking confirmed the experimental findings. Additionally, the molecules were evaluated in silico for ADMET and drug similarity features. The experimental observation enables the newly generated ethionamide derivatives to be attractive candidates for the creation of newer and better anti-TB agents.

Brazilian cohort study of risk factors associated with unsuccessful outcomes of drug resistant tuberculosis

Background

Treatment outcomes were evaluated of a cohort of new pulmonary tuberculosis (TB) cases that were rifampicin resistant, multidrug-resistant, or extensively resistant during 2013 and 2014 in Brazil. The objective of this study is to identify factors associated with unfavorable treatment outcomes for drug-resistant TB cases.

Methods

The Brazilian Special Tuberculosis Treatment Information System (SITE-TB) was the main data source. The independent variables were classified into four blocks (block I: individual characteristics; block II: clinical characteristics and proposed treatment; block III: treatment follow-up characteristics; and block IV: TB history). The category of successful therapeutic outcome was compared with lost to follow-up, failure, and death. Considering the multiple outcomes as the dependent variable, the odds ratios (OR) and its respective 95% confidence interval (95% CI) were estimated by multinomial logistic regression.

Results

After applying the exclusion criteria, 980 (98.8%) individuals were included in the study. Of these, 621 (63.4%) had successful treatment, 163 (16.6%) lost to follow-up, 76 (7.8%) failed, and 120 (12.2%) died. Important factors associated with lost to follow-up in the final model included use of illicit drugs (OR = 2.5 95% CI: 1.57–3.82). Outcome failure was associated with having disease in both lungs (OR = 2.0; 95% CI: 1.09–3.62) and using more than one or not using injectable medication (OR = 2.8; 95% CI: 1.05–7.69). Major factors for the death outcome were at least 60 years old (OR = 3.4; 95% CI: 1.90–6.03) and HIV positive (OR = 2.7; 95% CI: 1.45–4.83).

Conclusions

The factors associated with unfavorable treatment outcomes were different. Some of these factors are specific to each outcome, which reflects the complexity of providing care to these individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06756-7.

Adverse effects induced by second-line antituberculosis drugs: an update based on last WHO treatment recommendations for drug-resistant tuberculosis

Introduction: Tuberculosis (TB), a common condition worldwide, is still among the main infectious diseases with high mortality rates, both in adults and infants. Drug-resistant tuberculosis (DR-TB) drugs, revised by the World Health Organization (WHO) in 2018, are a prolonged and complex therapy associated with many adverse drug effects (ADEs).

Aim: To systematically review the ADEs of second-line anti-TB drugs reported in multicentric studies published after the latest WHO guidelines, compared with those from clinical trials published before 2018.

Material and methods: A PubMed search, using keywords (TB OR DR-TB) AND (adverse effects) AND “second-line anti-TB drugs”, resulted in 56 studies. Only two studies, published after the last update of WHO guidelines in 2018, reported ADEs.

Results: A total of 223 participants were included in the two selected studies. The use of multidrug regimens has been associated with an increased incidence of ADEs: 42 ADEs were recorded in 30 patients (26.3%) in the first study, while all patients had at least one ADE that occurred or worsened during treatment; and 19 (17%) had severe ADEs in the second study. However, both studies had a good favourable outcome rate (90% and 79.8%, respectively). Gastrointestinal disturbances, hepatotoxicity, headache and dizziness are the most common ADEs induced by a majority of second-line DR-TB treatments. A special attention should be given in the case of association of drugs determining QT interval (QT) prolongation on electrocardiogram, or psychiatric disorders.

Conclusions: Proper strategies about ADE management have to be planned for timely detection of the possible ADEs that can be induced by second-line anti-TB therapy.

Elucidating the Antimycobacterial Mechanism of Action of Decoquinate Derivative RMB041 Using Metabolomics

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), still remains one of the leading causes of death from a single infectious agent worldwide. The high prevalence of this disease is mostly ascribed to the rapid development of drug resistance to the current anti-TB drugs, exacerbated by lack of patient adherence due to drug toxicity. The aforementioned highlights the urgent need for new anti-TB compounds with different antimycobacterial mechanisms of action to those currently being used. An N-alkyl quinolone; decoquinate derivative RMB041, has recently shown promising antimicrobial activity against Mtb, while also exhibiting low cytotoxicity and excellent pharmacokinetic characteristics. Its exact mechanism of action, however, is still unknown. Considering this, we used GCxGC-TOFMS and well described metabolomic approaches to analyze and compare the metabolic alterations of Mtb treated with decoquinate derivative RMB041 by comparison to non-treated Mtb controls. The most significantly altered pathways in Mtb treated with this drug include fatty acid metabolism, amino acid metabolism, glycerol metabolism, and the urea cycle. These changes support previous findings suggesting this drug acts primarily on the cell wall and secondarily on the DNA metabolism of Mtb. Additionally, we identified metabolic changes suggesting inhibition of protein synthesis and a state of dormancy.

Elucidating the Antimycobacterial Mechanism of Action of Ciprofloxacin Using Metabolomics

In the interest of developing more effective and safer anti-tuberculosis drugs, we used a GCxGC-TOF-MS metabolomics research approach to investigate and compare the metabolic profiles of Mtb in the presence and absence of ciprofloxacin. The metabolites that best describe the differences between the compared groups were identified as markers characterizing the changes induced by ciprofloxacin. Malic acid was ranked as the most significantly altered metabolite marker induced by ciprofloxacin, indicative of an inhibition of the tricarboxylic acid (TCA) and glyoxylate cycle of Mtb. The altered fatty acid, myo-inositol, and triacylglycerol metabolism seen in this group supports previous observations of ciprofloxacin action on the Mtb cell wall. Furthermore, the altered pentose phosphate intermediates, glycerol metabolism markers, glucose accumulation, as well as the reduction in the glucogenic amino acids specifically, indicate a flux toward DNA (as well as cell wall) repair, also supporting previous findings of DNA damage caused by ciprofloxacin. This study further provides insights useful for designing network whole-system strategies for the identification of possible modes of action of various drugs and possibly adaptations by Mtb resulting in resistance.

Population Pharmacokinetics and Bayesian Dose Adjustment to Advance TDM of Anti-TB Drugs

Tuberculosis (TB) is still the number one cause of death due to an infectious disease. Pharmacokinetics and pharmacodynamics of anti-TB drugs are key in the optimization of TB treatment and help to prevent slow response to treatment, acquired drug resistance, and adverse drug effects. The aim of this review was to provide an update on the pharmacokinetics and pharmacodynamics of anti-TB drugs and to show how population pharmacokinetics and Bayesian dose adjustment can be used to optimize treatment. We cover aspects on preclinical, clinical, and population pharmacokinetics of different drugs used for drug-susceptible TB and multidrug-resistant TB. Moreover, we include available data to support therapeutic drug monitoring of these drugs and known pharmacokinetic and pharmacodynamic targets that can be used for optimization of therapy. We have identified a wide range of population pharmacokinetic models for first- and second-line drugs used for TB, which included models built on NONMEM, Pmetrics, ADAPT, MWPharm, Monolix, Phoenix, and NPEM2 software. The first population models were built for isoniazid and rifampicin; however, in recent years, more data have emerged for both new anti-TB drugs, but also for defining targets of older anti-TB drugs. Since the introduction of therapeutic drug monitoring for TB over 3 decades ago, further development of therapeutic drug monitoring in TB next steps will again depend on academic and clinical initiatives. We recommend close collaboration between researchers and the World Health Organization to provide important guideline updates regarding therapeutic drug monitoring and pharmacokinetics/pharmacodynamics.

The Xpert® MTB/RIF diagnostic test for pulmonary and extrapulmonary tuberculosis in immunocompetent and immunocompromised patients: Benefits and experiences over 2 years in different clinical contexts

Xpert^® MTB/RIF has been widely used for tuberculosis (TB) diagnosis in Brazil, since 2014. This prospective observational study aimed to evaluate the performance of Xpert in different contexts during a two-year period: (i) laboratory and clinical/epidemiological diagnosis; (ii) HIV-positive and -negative populations; (iii) type of specimens: pulmonary and extrapulmonary. Overall, 924 specimens from 743 patients were evaluated. The performance of the assays was evaluated considering culture (Lowenstein Jensen or LJ medium) results and composite reference standard (CRS) classification as gold standard. According to CRS evaluation, 219 cases (29.5%) were classified as positive cases, 157 (21.1%) as ‘possible TB’, and 367 (49.3%) as ‘not TB’. Based on culture, Xpert and AFB smear achieved a sensitivity of 96% and 62%, respectively, while based on CRS, the sensitivities of Xpert, AFB smear, and culture were 40.7%, 20%, and 25%, respectively. The pooled sensitivity and specificity of Xpert were 96% and 94%, respectively. Metric evaluations were similar between pulmonary and extrapulmonary samples against culture, whereas compared to CRS, the sensitivities were 44.6% and 29.3% for the pulmonary and extrapulmonary cases, respectively. The Xpert detected 42/69 (60.9%) patients with confirmed TB and negative culture on LJ medium, and 52/69 (75.4%) patients with negative AFB smear results. There was no significant difference in the diagnostic accuracy based on the types of specimens and population (positive- and negative-HIV). Molecular testing detected 13 cases of TB in culture-negative patients with severe immunosuppression. Resistance to rifampicin was detected in seven samples. Herein, Xpert showed improved detection of pulmonary and extrapulmonary TB cases, both among HIV-positive and -negative patients, even in cases with advanced immunosuppression, thereby performing better than multiple other diagnostic parameters.

Multidrug-Resistant Tuberculosis in Portugal: Patients’ Perception of the Challenges Faced during Treatment

<b><i>Introduction:</i></b> The increase in drug-resistant tuberculosis (TB) threatens global progress in eliminating TB, and constitutes a major challenge for patients, health-care workers and health services. Treatment for multidrug-resistant TB (MDR-TB) can last almost 2 years, and is more expensive, more toxic, and less effective than treating TB caused by drug-sensitive bacilli. This study aims to analyze patients’ narratives about the challenges they face during MDR-TB treatment and identify the support factors that help patients being treated in the most populous district of Portugal. <b><i>Methods:</i></b> Semi-structured interviews were conducted with patients being treated for MDR-TB. The interviews were coded using thematic analysis. They were audio-recorded, transcribed, and transported into NVivo v12 for data management and coding. <b><i>Results:</i></b> Depression, social discrimination, and the side effects of drugs are the main challenges faced by patients with MDR-TB. A good relationship of the patients with the health team, emotional support, and supervised treatment stand out as the factors that generate better adherence and treatment success. <b><i>Conclusion:</i></b> In addition to modern diagnostic techniques and new treatments, MDR-TB can be fought by focusing on the care and needs of patients. We suggest that the Lisbon Tuberculosis Program adopts the following measures: build the health-care team’s capacity to identify symptoms of depression early, increase public awareness of the disease, expand the multidisciplinary team, and expand the options for individualized social support for patients.

The pharmacokinetics of para-aminosalicylic acid and its relationship to efficacy and intolerance

Following its introduction as an antituberculosis agent close to 75 years ago, the use of para-aminosalicylic acid (PAS) has been limited by gastrointestinal intolerance and multiple formulations were produced in attempts to reduce its occurrence. More recently, an enteric-coated, granular, slow-release PAS formulation (PASER) was introduced and is now in wide-spread use for the treatment of drug-resistant tuberculosis. The current PASER dosing regimen is based on recommendations derived from older studies using a variety of different PAS formulations and relegate PAS to a role as an exclusively bacteriostatic agent. However, there is ample evidence that if sufficiently high serum concentrations are reached, PAS can be bactericidal and that intolerance following once daily dosing, that aids the achievement of such concentrations, is no worse than that following intermittent daily dosing. In particular, prevention of resistance to companion drugs appears to be dependent on the size of the single dose, and hence the peak concentrations, and not on maintaining serum levels consistently above minimum inhibitory concentration. We present a narrative review of the development of PAS formulations, dosing practices, and published data regarding pharmacokinetics and pharmacodynamics and the relationship of PAS dosage to intolerance and efficacy. Our conclusions suggests that we are at present not using PAS to its maximum ability to contribute to regimen efficacy and protect companion drugs.

The prevalence and risks of major comorbidities among inpatients with pulmonary tuberculosis in China from a gender and age perspective: a large-scale multicenter observational study

In clinical practice, PTB patients have concurrent many types of comorbidities such as pneumonia, liver disorder, diabetes mellitus, hematological disorder, and malnutrition. Detecting and treating specific comorbidities and preventing their development are important for PTB patients. However, the prevalence of most comorbid conditions in patients with PTB is not well described. We conducted a large-scale, multicenter, observational study to elucidate and illustrate the prevalence rates of major comorbidities in inpatients at 21 hospitals in China. The 19 specific comorbidities were selected for analysis in this patient cohort, and stratified the inpatient cohort according to age and gender. A total of 355,929 PTB inpatients were included, with a male:female ratio of 1.98 and the proportion of ≥ 65 years PTB inpatients was the most. Approximately 70% of PTB inpatients had at least one defined type of comorbidity. The prevalence of 19 specific comorbidities in inpatients with PTB was analyzed, with pneumonia being the most common comorbidity. The prevalence of most comorbidities was higher in males with PTB except thyroid disorders, mental health disorders, etc. The prevalence of defined most comorbidities in patients with PTB tended to increase with increasing age, although some specific comorbidities tended to increase initially then decrease with increasing age. Our study describes multiple clinically important comorbidities among PTB inpatients, and their prevalence between different gender and age groups. The results will enhance the clinical aptitude of physicians who treat patients with PTB to recognize, diagnose, and treat PTB comorbidities early.

Transbuccal Delivery of Isoniazid: Ex Vivo Permeability and Drug-Surfactant Interaction Studies

The oral administration of isoniazid (INH) may lead to discontinuation of tuberculosis treatment due to drug-related hepatotoxicity events, and thus, the transbuccal delivery of this drug was investigated, for the first time, as an alternative administration route. Ex vivo permeability assays were performed in Franz-type diffusion chambers, applying INH alone and in combination with sodium dodecyl sulfate (SDS) and sodium taurocholate (ST). After confirming the formation of micelle structures by dynamic light scattering analysis, UV-visible spectroscopy and zeta potential analyses were used to investigate drug-micelle interactions. In zeta potential analyses, no electrostatical interactions were identified for both surfactants in saliva buffer pH 6.8. Spectrophotometric analyses, in turn, indicated chemical interactions between INH and SDS in both pH values (2.0 and 6.8) whereas no interaction between the drug and ST was observed. Despite the interaction between SDS and drug, this surfactant increased the buccal transport rate of INH by approximately 11 times when compared with the control. In contrast, ST did not increase the drug permeability. The INH retention in SDS-treated mucosa was significantly higher when compared with the control and an effect on intercellular lipids was suggested. In vivo studies are needed to confirm the high INH absorption found here. Grapical abstract.

Population Pharmacokinetics of Cycloserine and Pharmacokinetic/Pharmacodynamic Target Attainment in Multidrug-Resistant Tuberculosis Patients Dosed with Terizidone

Cycloserine is a WHO group B drug for the treatment of multidrug-resistant tuberculosis (TB). Pharmacokinetic/pharmacodynamic data for cycloserine when dosed as terizidone are sparse. The aim of this analysis was to describe the population pharmacokinetics of cycloserine when administered as terizidone and predict the doses of terizidone attaining cycloserine exposures associated with efficacy. The plasma cycloserine level was measured 2 to 6 weeks after treatment initiation in patients hospitalized for second-line tuberculosis treatment. The pretreatment MICs of cycloserine were determined for the clinical isolates. We enrolled 132 participants with rifampicin-resistant TB; 79 were HIV positive. The median pretreatment MIC was 16 mg/liter. A one-compartment disposition model with two clearance pathways, nonrenal (0.35 liters/h) and renal (0.43 liters/h), described cycloserine pharmacokinetics well. Nonrenal clearance and the volume of distribution were allometrically scaled using fat-free mass. Smoking increased nonrenal clearance by 41%. Simulations showed that with daily doses of terizidone (750 mg and 1,000 mg for patients weighing ≤45 kg and >45 kg, respectively), the probability of maintaining the plasma cycloserine concentration above the MIC for more than 30% of the dosing interval (30% T>MIC) (which is associated with a 1.0-log10-CFU/ml kill in vitro) exceeded 90% at MIC values of ≤16 mg/liter, but the proportion of patients achieving 100% T>MIC (which is associated with the prevention of resistance) was more than 90% only at MICs of ≤8 mg/liter. Based on a target derived in vitro, the WHO-recommended doses of terizidone are effective for cycloserine MICs of ≤8 mg/liter, and higher doses are required to prevent the development of resistance.

Multi-Drug Resistant and Extensively-Drug Resistant Tuberculosis

India is one of the high burden countries for tuberculosis (TB) including multi-drug resistant TB (MDR-TB) and extensively-drug resistant (XDR) TB. Drug-resistant (DR) TB has threatened the TB care and is a major health problem in many countries; treatment of DR TB has been difficult requiring use of reserve or second-line drugs, cost factors, has extensive side-effect profile and long duration of treatment. Treatment in MDR-TB are increasingly becoming individualised mainly due to preference for oral over injectable, results of drug susceptibility testing (DST), population resistance levels, history of previous TB treatment, drug tolerability and drug-to-drug interactions. Bedaquilline (BDQ) and delaminid (DLM) are new drugs available for treatment of these patients. World Health Organization (WHO) recommends use of BDQ in more than 15 y (>15 kg) patients only. Under Revised National Tuberculosis Control Programme (RNTCP) the use of this drug is recommended for patients older than 18 y only. Under RNTCP, the use of DLM is approved in children 6 y and above. Pediatric MDR/XDR TB treatment outcome with newer anti-TB drugs and regimen is lacking. Children when treated with individualized regimens have improved survival.

In vitro and in vivo toxicity evaluation of non-neuroleptic phenothiazines, antitubercular drug candidates

The phenothiazine-derived antipsychotic drugs, such as chlorpromazine and thioridazine, are bactericidal against drug-sensitive and drug-resistant strains of Mycobacterium tuberculosis, but produce undesirable side effects at clinically relevant doses. We have previously modified four novel phenothiazines and maintained their antimycobacterial activity. This study evaluated the pharmacological and toxicity profiles of these novel non-neuroleptic phenothiazines, PTZ3, PTZ4, PTZ31 and PTZ32, for their metabolic stability, kinetic solubility and potential cytotoxic effects in vitro. To further support the safet use of these drug candidates, the in vivo pharmacological and toxicity profiles were assessed in C57BL/6 mice via single or repeated oral gavage. In acute toxicity studies, all four modified phenothiazines showed favourable safety in mice. When treated daily with 100 mg/kg of PTZ3 and PTZ4 for 2 weeks, mice displayed no signs of toxicity. Alternatively, treatment with PTZ31 resulted in 20% mortality with no toxicity evident in biochemical or histological analysis, while exposure to PTZ32 resulted in a 45% survival with increased serum concentrations of uric acid and alkaline phosphatase. The combined non-neuroleptic and antimycobacterial effects of the novel phenothiazines PTZ3, PTZ4, PTZ31 and PTZ32 demonstrated favourable pharmacological and toxicity profiles in this study, highlight the potential of these compounds as suitable anti-tuberculosis drug candidates.

A comparison of hepatoprotective activity of Bacoside to Silymarin treatment against a combined Isoniazid and Rifampin-induced hepatotoxicity in female Wistar rats

The liver is an important organ that plays a vital role in homeostasis maintenance and regulation. Any liver damage or injury caused by drugs or chemicals is called hepatotoxicity. Isoniazid and rifampin are drugs used separately to treat tuberculosis but have unique side effects and potential hepatotoxicity. The metabolism of isoniazid (INH) and rifampin (RIF) takes place in liver hence hepatotoxicity is the main cause of their continuous use. Bacoside was obtained from the plant Bacopa monnieri, a dammarene type triterpenoid saponin, found distributed throughout India. Bacoside has been used as a nerve tonic, a free radical scavenger, and antioxidant. It is known that the combined INH-RIF induced hepatotoxicity can be antagonized by maintaining hepatocyte membrane integrity in rats. Silymarin, an herbal drug, and its component silybin were reported to work as lipid peroxidation inhibitors and antioxidants which scavenge free radicals. Due to minimal toxicity and no adverse drug interactions, Silymarin is used to treat various medically confirmed hepatic disorders. The aim of this study was to evaluate the beneficial effect of Bacoside against INH- and RIF-induced toxicity in livers of Wistar albino rats. Four experimental groups of rats were used to study four parameters; bodyweight, liver enzyme markers, liver antioxidant, and liver histopathology. INH- and RIF-treated rats showed abnormalities in liver markers which were normalized by Bacoside and that seems similar to the normal control and Silymarin-treated groups. Thus, the current study demonstrated the hepatoprotective effect of Bacoside against INH- and RIF-induced toxicity in Wistar albino rats.

Efficient computational model for identification of antitubercular peptides by integrating amino acid patterns and properties

Tuberculosis (TB) is a leading killer caused by Mycobacterium tuberculosis. Recently, anti-TB peptides have provided an alternative approach to combat antibiotic tolerance. We have developed an effective computational predictor, identification of antitubercular peptides (iAntiTB), by the integration of multiple feature vectors deriving from the amino acid sequences via random forest (RF) and support vector machine (SVM) classifiers. The iAntiTB combines the RF and SVM scores via linear regression to enhance the prediction accuracy. To make a robust and accurate predictor, we prepared the two datasets with different types of negative samples. The iAntiTB achieved area under the ROC curve values of 0.896 and 0.946 on the training datasets of the first and second datasets, respectively. The iAntiTB outperformed the other existing predictors.

Is hypothyroidism rare in multidrug resistance tuberculosis patients on treatment? A systematic review and meta-analysis

BACKGROUND

Hypothyroidism is one of the adverse drug reactions that associated with Multidrug Resistant Tuberculosis (MDR-TB) medications. Extremely variable magnitude of hypothyroidism in MDR-TB patients has been reported from different parts of the world. However, there is no evidence that tried to estimate the pooled prevalence of hypothyroidism to confirm the rareness of hypothyroidism in MDR-TB patients on treatment. Therefore, we did a systematic review and meta-analysis to estimate the prevalence of hypothyroidism in MDR-TB patients on treatment, and to summarize the demographic and clinical characteristics of the patients.

METHODS

We conducted a systematic review and meta-analysis on studies reported around the world on the prevalence of hypothyroidism in MDR-TB patients on treatment. We searched electronic databases: PubMed/Medline, EMBASE, CINAHL, Science Direct, Academic Search Complete and Google scholar for English language articles without limiting publication year. We also reviewed the bibliographies of relevant studies and conducted an electronic search for relevant conference abstracts. Eligible studies were cross-sectional and cohort studies that included at least five participants. We used a random-effects model to estimate the pooled prevalence of hypothyroidism. The registration number of this review study protocol is CRD42018109237.

RESULTS

We included 30 studies and pooled data on a total of 6,241 MDR-TB patients. The crude prevalence of hypothyroidism was extremely heterogeneous. The pooled prevalence of hypothyroidism in MDR-TB patients on treatment was 17.0% (95% CI: 13.0-20.0). Ethionamide and para-aminosalicylic acid (PAS) were the most frequently reported drugs that associated with the occurrence of hypothyroidism.

CONCLUSION

This review revealed that hypothyroidism is not a rare adverse drug reaction in MDR-TB patients on treatment. Ethionamide and PAS were the most frequently reported drugs that associated with the occurrence of hypothyroidism. Screening of hypothyroidism in MDR-TB patients on treatment is important while targeting patients on Ethionamide and PAS based treatment regimen.

A significant therapeutic effect of silymarin administered alone, or in combination with chemotherapy, in experimental pulmonary tuberculosis caused by drug-sensitive or drug-resistant strains: In vitro and in vivo studies

For many years, tuberculosis (TB) has been a major public health problem worldwide. Advances for treatment and eradication have been very limited. Silymarin (Sm) is a natural product with antioxidant and hepatoprotective activities that has been proposed as a complementary medicine to reduce the liver injury produced by the conventional anti-TB chemotherapy. Sm also has immunoregulatory and microbicide properties. In this study, we determined the effect of Sm on the growth control of mycobacteria. In vitro studies showed that Sm and Silibinin (the principal active compound of Sm) have microbicidal activity against drug-sensitive and multidrug-resistant (MDR) mycobacteria, induce the production of protective cytokines from infected macrophages, and improve the growth control of mycobacteria (p ≤ 0.0001). Studies in vivo using a model of progressive pulmonary TB in BALB/c mice infected with drug-sensitive or MDR mycobacteria have shown that Sm induces significant expression of Th-1 cytokines such as IFN-γ and IL-12 as well as TNFα, which produce significant therapeutic activity when administered alone and apparently have a synergistic effect with chemotherapy. These results suggest that Sm has a bactericidal effect and can contribute to the control and establishment of a TH1 protective immune response against mycobacterial infection. Thus, it seems that this flavonoid has a promising potential as adjuvant therapy in the treatment of TB.

The systematic modeling studies and free energy calculations of the phenazine compounds as anti-tuberculosis agents

Phenazine compounds have good activity against Mycobacterium tuberculosis (MTB). Based on the reported activities that were obtained in MTB H37Rv, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was built to design novel compounds against MTB. A fivefold cross-validation method and external validation were used to analyze the accuracy of forecasting. The model has a cross-validation coefficient q²=0.7 and a non-cross-validation coefficient r² = 0.903, indicating that the model has good predictive possibility. The design of anti-pneumococcus MTB compounds was guided by the obtained 3D-QSAR model, and several compounds with better activity were obtained. To test the activity of these compounds, molecular docking, molecular dynamics simulation, and post-simulation analysis of the already reported drug targets in MTB were carried out. Among the total 15 drug targets, only three targets (Rv2361c, Rv2965c, and Rv3048c) were selected based on the docking results. Initial results reported that these compounds possessed good inhibition activity for Rv2361c. The top nine complexes of Rv2361 ligands were only subjected to MD simulation which resulted in a stable dynamics of the structures and showed a residual fluctuation in inhibitors binding pocket. Free energy reported that overall, the derivatives hold strong energy against the protein target. Energetic contribution results showed that residues, Asp76, Arg80, Asn124, Arg127, Arg244, and Arg250, play a major role in total energy. Systems biology approach validates shortlisted drug effect on the entire system which might be useful to predict potential drug in wet lab as well. Communicated by Ramaswamy H. Sarma.

Prediction of Antitubercular Peptides From Sequence Information Using Ensemble Classifier and Hybrid Features

Tuberculosis is one of the leading cause of death worldwide, particularly due to evolution of drug resistant strains. Antitubercular peptides may provide an alternate approach to combat antibiotic tolerance. Sequence analysis reveals that certain residues (e.g., Lysine, Arginine, Leucine, Tryptophan) are more prevalent in antitubercular peptides. This study describes the models developed for predicting antitubercular peptides by using sequence features of the peptides. We have developed support vector machine based models using different sequence features like amino acid composition, binary profile of terminus residues, dipeptide composition. Our ensemble classifiers that combines models based on amino acid composition and N5C5 binary pattern, achieves highest Acc of 73.20% with 0.80 AUROC on our main dataset. Similarly, the ensemble classifier achieved maximum Acc 75.62% with 0.83 AUROC on secondary dataset. Beside this, hybrid model achieves Acc of 75.87 and 78.54% with 0.83 and 0.86 AUROC on main and secondary dataset, respectively. In order to facilitate scientific community in designing of antitubercular peptides, we implement above models in a user friendly webserver (http://webs.iiitd.edu.in/raghava/antitbpred/).

Unexpected Pregnancy during Treatment of Multidrug-resistant Tuberculosis

Several drugs used in the treatment of multidrug-resistant tuberculosis (MDR-TB) have been reported as teratogenic. Treatment of such cases during gestation is disputable. Some experts favor the termination of pregnancy, whereas others suggest reducing the dose of teratogenic drugs or even suspending the regimen during pregnancy. There have been no clinical trials on the subject, but case reports and case series show excellent outcomes for children exposed during pregnancy to second-line agents, indicating that aggressive management of gestational MDR-TB may benefit not only the mother but also the fetus. We present a case of pregnancy in a teenager while she was under treatment for MDR-TB and continued with full treatment and nevertheless delivered a healthy child.

Enhancement of the antimycobacterial activity of macrophages by ajoene

Ajoene, a garlic-derived sulfur-containing compound, has broad-spectrum antimicrobial activity. To assess the potential of ajoene for treating tuberculosis (TB), we determined whether it induces the stress response of the endoplasmic reticulum (ER), which plays an important role in TB. We showed that ajoene stimulation induced the production of ER stress sensor molecules and reactive oxygen species (ROS) levels. Ajoene-induced ROS production was dependent on c-Jun N-terminal kinase (JNK) activation. Interestingly, the inhibition of JNK activity and suppression of ROS production reduced ajoene-induced CHOP production in macrophages. Because ER stress activates autophagy, the activation of which suppresses the growth of mycobacteria, we investigated the ajoene-induced production of autophagy-related factors, including LC3-II, P62 and Beclin-1. As expected, ajoene treatment increased the levels of these factors in RAW 264.7 cells. Remarkably, the total amount of Mycobacterium tuberculosis (Mtb) H37Rv was significantly reduced in ajoene-treated RAW 264.7 cells. The treatment of macrophages with ajoene resulted in the activation of JNK, induction of ROS synthesis and accumulation of ROS, possibly leading to the activation of ER stress and autophagy. These results reveal the mechanism of the antimycobacterial effects of ajoene against Mtb H37Rv. Our findings might facilitate the development of novel therapies for patients with TB.

Poncet's disease after the intravesical instillation of Bacillus Calmette-Guérin (BCG): a case report

BACKGROUND

Poncet's disease is a rare syndrome characterized by articular impairment in a form of rare tuberculid. One of the theories of its cause involves an autoimmune response induced by the intravesical administration of the Calmette-Guerin Bacillus or the treatment of bladder carcinoma. Furthermore, there may be an appearance of oligoarticular or polyarticular arthritis, beginning 1-3 months after the start of therapy. Few physicians know the disease and the literature related to that syndrome is scarce and restricted to case reports, which contributes to its under diagnosis.

CASE PRESENTATION

Female patient, 64 years old, Caucasian, in whom was noticed firstly dark urine, without haematuria or dysuria. Later felt also colic pain in the hypogastric region. Microscopically, the conclusive diagnosis was a high grade non-invasive papillary urothelial carcinoma. Thereupon, the treatment of the tumour began with transurethral resection technique and intravesical instillation of Calmette-Guérin Bacillus as adjuvant treatment. Eight months after the beginning of treatment, the lingering presence of the carcinoma was identified. Nevertheless, arthritis was identified through radiographs, after an increase in the clavicle capitation, right knee and left ankle in bone scintigraphy. Coinciding with the joint manifestations, the patient developed fever and purulent urethral discharge (culture was negative). Therefore, trying to investigate the cause of the arthritis, Purified Protein Derivate was taken, with reactive results. An increase of acute phase reactants was found, with other tests resulting normal: blood chemistry, Complete Blood Count, immunology and serology. Human Leukocyte Antigen typing by polymerase chain reaction revealed the presence of A24/AX, B44, B27, BW4/BW4, DQ7 and DQ5. Consequently, Poncet's disease was the diagnostic conclusion. The treatment with intravesical Calmette-Guérin Bacillus was immediately discontinued. The patient received corticosteroids associated with etoricoxib and isoniazid for 4 months, achieving disappearance of the inflammatory joint signs in 3 months. After 6 months, no joint pain recurrence or other manifestations suggesting active disease had been seen.

CONCLUSIONS

Therefore, such diagnosis should be considered when confronted with an osteoarticular clinical picture in patients treated with intravesical Calmette-Guérin Bacillus, especially patients with HLA-B27 (+) and B7 (+), as Poncet's disease is a reactive arthritis.

Evaluation of para-Aminosalicylic Acid as a Substrate of Multiple Solute Carrier Uptake Transporters and Possible Drug Interactions with Nonsteroidal Anti-inflammatory Drugs In Vitro

para-Aminosalicylic acid (PAS) is a second-line antituberculosis drug that has been used to treat multidrug-resistant and extensively drug-resistant tuberculosis for more than 60 years. Renal secretion and glomerular filtration are the major pathways for the elimination of PAS. We comprehensively studied PAS transport by using cell lines that overexpressed various transporters and found that PAS acts as a novel substrate of an organic anionic polypeptide (OATP1B1), organic cationic transporters (OCT1 and OCT2), and organic anion transporters (OAT1 and OAT3) but is not a substrate of any ATP-binding cassette (ABC) transporters. Net PAS uptake was measured, and the transport affinities (K_m values) for OATP1B1, OCT1, OCT2, OAT1, and OAT3 were found to be 50.0, 20.3, 28.7, 78.1, and 100.1 μM, respectively. The net uptake rates suggested that renal OAT1 and OAT3 play relatively major roles in PAS elimination. The representative inhibitors rifampin for OATP1B1, probenecid for OAT1 and OAT3, and verapamil for OCT1 and OCT2 greatly inhibited PAS uptake, suggesting that PAS is dependent on multiple transporters for uptake. We also evaluated nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs), and metformin for the inhibition of PAS uptake via these transporters. Half-maximal (50%) inhibitory concentrations (IC₅₀s) were kinetically determined and used to predict the drug-drug interactions (DDIs) affecting these transporters' activity toward PAS. We found that rifampin, probenecid, ibuprofen, naproxen, cimetidine, and quinidine each exhibited a significant potential for in vivo DDIs with PAS. In this study, PAS was found to be a novel substrate of several transporters, and drugs that inhibit these transporters can reduce PAS elimination.

A randomized placebo-controlled pilot study of the efficacy and safety of D-cycloserine in people with chronic back pain

BACKGROUND

Few effective pharmacological treatment options exist for chronic back pain, the leading cause of disability in the US, and all are associated with significant adverse effects.

OBJECTIVE

To determine the efficacy and safety of D-cycloserine, a partial agonist to the N-methyl-D-aspartate receptor, in the treatment of chronic low back pain.

METHODS

A total of 41 participants with chronic back pain who met all inclusion and exclusion criteria were enrolled in a double-blind, placebo-controlled randomized pilot trial of D-cycloserine. Treatment was administered orally for six weeks at escalating daily doses of 100 mg, 200 mg, and 400 mg, each for two weeks. The primary outcome measure was back pain intensity using the Numeric Rating Scale (0-10). Secondary measures were back pain-related questionnaires: McGill Pain Questionnaire short form, painDETECT, PANAS, and BDI. The pre-specified analysis was a two-way repeated measures analysis of variance.

RESULTS

A treatment difference was observed between groups treated with D-cycloserine and placebo at six weeks of 1.05 ± 3.1 units on the Numeric Rating Scale, with an effect size of 0.4 and p = 0.14. This trend of better chronic back pain relief with D-cycloserine was also observed in the secondary measures. No safety issues were seen.

CONCLUSION

The difference in mean pain between the D-cycloserine and placebo groups did not reach statistical significance. However, a clinically meaningful effect size in the magnitude of pain relief was observed with a consistent pattern across multiple outcome measures with good safety, supporting further research into the effectiveness of D-cycloserine for chronic back pain.

Pharmacokinetics of Ethionamide Delivered in Spray-Dried Microparticles to the Lungs of Guinea Pigs

The use of ethionamide (ETH) in treating multidrug-resistant tuberculosis is limited by severe side effects. ETH disposition after pulmonary administration in spray-dried particles might minimize systemic exposure and side effects. To explore this hypothesis, spray-dried ETH particles were optimized for performance in a dry powder aerosol generator and exposure chamber. ETH particles were administered by the intravenous (IV), oral, or pulmonary routes to guinea pigs. ETH appearance in plasma, bronchoalveolar lavage, and lung tissues was measured and subjected to noncompartmental pharmacokinetic analysis. Dry powder aerosol generator dispersion of 20% ETH particles gave the highest dose at the exposure chamber ports and fine particle fraction of 72.3%. Pulmonary ETH was absorbed more rapidly and to a greater extent than orally administered drug. At T_max, ETH concentrations were significantly higher in plasma than lungs from IV dosing, whereas insufflation lung concentrations were 5-fold higher than in plasma. AUC_(0-t) (area under the curve) and apparent total body clearance (CL) were similar after IV administration and insufflation. AUC_(0-t) after oral administration was 6- to 7-fold smaller and CL was 6-fold faster. Notably, ETH bioavailability after pulmonary administration was significantly higher (85%) than after oral administration (17%). These results suggest that pulmonary ETH delivery would potentially enhance efficacy for tuberculosis treatment given the high lung concentrations and bioavailability.

Thyroid function in multidrug-resistant tuberculosis patients with or without human immunodeficiency virus (HIV) infection before commencement of MDR-TB drug regimen

BACKGROUND

Mycobacterium tuberculosis and human immunodeficiency virus (HIV) are known to cause abnormal thyroid function. There is little information on whether HIV infection aggravates alteration of thyroid function in patients with MDR-TB.

OBJECTIVES

This study was carried out to determine if HIV co-infection alters serum levels of thyroid hormones (T3, T4) and thyroid stimulating hormone (TSH) in patients with MDR-TB patients and to find out the frequency of subclinical thyroid dysfunction before the commencement of MDR-TB therapy.

METHODS

This observational and cross-sectional study involved all the newly admitted patients in MDR-TB Referral Centre, University College Hospital, Ibadan, Nigeria between July 2010 and December 2014. Serum levels of thyroid stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were determined using ELISA.

RESULTS

Enrolled were 115 patients with MDR-TB, out of which 22 (19.13%) had MDR-TB/HIV co-infection. Sick euthyroid syndrome (SES), subclinical hypothyroidism and subclinical hyperthyroidism were observed in 5 (4.35%), 9 (7.83%) and 2 (1.74%) patients respectively. The median level of TSH was insignificantly higher while the median levels of T3 and T4 were insignificantly lower in patients with MDR-TB/HIV co-infection compared with patients with MDRT-TB only.

CONCLUSION

It could be concluded from this study that patients with MDR-TB/HIV co-infection have a similar thyroid function as patients having MDR-TB without HIV infection before commencement of MDR-TB drug regimen. Also, there is a possibility of subclinical thyroid dysfunction in patients with MDR-TB/HIV co-infection even, before the commencement of MDR-TB therapy.

Repurposing drugs for treatment of tuberculosis: a role for non-steroidal anti-inflammatory drugs

INTRODUCTION

The number of cases of drug-resistant Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), has risen rapidly in recent years. This has led to the resurgence in repurposing existing drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), for anti-TB treatment.

SOURCES OF DATA

Evidence from novel drug screening in vitro, in vivo, pharmacokinetic/pharmacodynamics analyses and clinical trials has been used for the preparation of this systematic review of the potential of NSAIDs for use as an adjunct in new TB chemotherapies.

AREAS OF AGREEMENT

Certain NSAIDs have demonstrated inhibitory properties towards actively replicating, dormant and drug-resistant clinical isolates of M. tuberculosis cells.

AREAS OF CONTROVERSY

NSAIDs are a diverse class of drugs, which have reported off-target activities, and their endogenous antimicrobial mechanism(s) of action is still unclear.

GROWING POINTS

It is essential that clinical trials of NSAIDs continue, in order to assess their suitability for addition to the current TB treatment regimen. Repurposing molecules such as NSAIDs is a vital, low-risk strategy to combat the trend of rapidly increasing antibiotic resistance.

Pre-harvest cane burning and health: the association between school absences and burning sugarcane fields

The objective of this study was to investigate an association between pre-harvest sugarcane burning and respiratory diseases in children under five years of age. The following data were collected in five schools in the city of Araraquara, SP, Southeastern Brazil, between March and June 2009: daily records of absences and the reasons stated for these absences, total concentration of suspended particulate matter (µg/m³), and air humidity. The relationship between the percentage of school absences due to respiratory problems and the concentration of particulate matter in March and from April to June presented a distinct behavior: absences increased alongside the increase in particulate matter concentration. The use of school absences as indicators of this relationship is an innovative approach.

Complications of tuberculosis

PURPOSE OF REVIEW

Diagnosis and management of tuberculosis (TB) remains challenging and complex because of the heterogeneity of disease presentations. Despite effective treatment, TB disease can lead to significant short-and long-term health consequences. We review potential acute and chronic complications of TB disease and current management approaches.

RECENT FINDINGS

Acute and subacute complications of TB disease are attributable to structural damage or vascular compromise caused by Mycobacterium tuberculosis, as well as metabolic abnormalities and host inflammatory responses. TB-related sepsis is a life-threatening acute complication for which current diagnostic and management approaches are likely inadequate. Therapeutic intensification and usage of immunomodulators are areas of ongoing research. Paradoxical reaction or symptom worsening during TB treatment may benefit from corticosteroids. Despite successful cure of TB, chronic complications can arise from anatomic alterations at disease sites. Examples include mycetomas developing within residual TB cavities, impaired pulmonary function, or focal neurologic deficits from tuberculomas.

SUMMARY

Effective management of TB requires attention to potential structural, metabolic, vascular, and infectious complications. In some instances, individualizing treatment regimens may be necessary. Imunosuppression and other host factors predispose to complications; others occur despite adequate treatment. Public health TB programs and health systems require additional resources to provide comprehensive TB and post-TB care.

Role of therapeutic drug monitoring in pulmonary infections: use and potential for expanded use of dried blood spot samples

Respiratory tract infections are among the most common infections in men. We reviewed literature to document their pharmacological treatments, and the extent to which therapeutic drug monitoring (TDM) is needed during treatment. We subsequently examined potential use of dried blood spots as sample procedure for TDM. TDM was found to be an important component of clinical care for many (but not all) pulmonary infections. For gentamicin, linezolid, voriconazole and posaconazole dried blood spot methods and their use in TDM were already evident in literature. For glycopeptides, β-lactam antibiotics and fluoroquinolones it was determined that development of a dried blood spot (DBS) method could be useful. This review identifies specific antibiotics for which development of DBS methods could support the optimization of treatment of pulmonary infections.

Anti-tuberculosis drugs adverse reactions: a review of the Iranian literature

INTRODUCTION

Tuberculosis (TB) treatment, in particular therapy for multidrug-resistant TB (MDR-TB), is associated with toxicities and adverse drug reactions (ADRs).

AREAS COVERED

This paper reviews Iranian literature reporting ADRs which occurred during tuberculosis treatment. English language papers were sourced from PubMed, ScienceDirect, Wiley, Ovid and Proquest, with Google Scholar searched for Persian language articles. Reported ADRs, proportion of patients with ADRs, risk factors and determinants, as well as the characteristics of the studies were reviewed. 21 articles were included; about 60% of them were in English and three included patients with MDR-TB. The ratio of ADR per capita was 1.9 (in 6 studies) and 33.63% of patients developed an ADR (in 7 studies). Hepatitis (2.5 - 45.3%) was reported in nearly all of the studies. The mean time from initiation of medication to development of hepatitis ranged from 4.67 to 25.25 days (in 6 studies). Most cases of mortality were due to hepatotoxicity. Except for comorbidities and female gender, other risk factors such as HIV and length of hospitalization were only reported in one article.

EXPERT OPINION

The pattern of ADRs in Iranian articles was found to be similar to many other studies in the present review. We suggest that future studies resolve the confounding factors in this area that are mentioned in this review.

Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin

Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity.

Kinetic mechanism and inhibition of Mycobacterium tuberculosis D-alanine:D-alanine ligase by the antibiotic D-cycloserine

D-cycloserine (DCS) is an antibiotic that is currently used in second-line treatment of tuberculosis. DCS is a structural analogue of D-alanine, and targets two enzymes involved in the cytosolic stages of peptidoglycan synthesis: alanine racemase (Alr) and D-alanine:D-alanine ligase (Ddl). The mechanisms of inhibition of DCS have been well-assessed using Alr and Ddl enzymes from various bacterial species, but little is known regarding the interactions of DCS with the mycobacterial orthologues of these enzymes. We have over-expressed and purified recombinant Mycobacterium tuberculosis Ddl (MtDdl; Rv2981c), and report a kinetic examination of the enzyme with both its native substrate and DCS. MtDdl is activated by K(+), follows an ordered ter ter mechanism and displays distinct affinities for D-Ala at each D-Ala binding site (K(m,D-Ala1) = 0.075 mm, K(m,D-Ala2) = 3.6 mm). ATP is the first substrate to bind and is necessary for subsequent binding of D-alanine or DCS. The pH dependence of MtDdl kinetic parameters indicate that general base chemistry is involved in the catalytic step. DCS was found to competitively inhibit D-Ala binding at both MtDdl D-Ala sites with equal affinity (K(i,DCS1) = 14 μm, K(i,DCS2) = 25 μm); however, each enzyme active site can only accommodate a single DCS molecule at a given time. The pH dependence of K(i,DCS2) revealed a loss of DCS binding affinity at high pH (pK(a) = 7.5), suggesting that DCS binds optimally in the zwitterionic form. The results of this study may assist in the design and development of novel Ddl-specific inhibitors for use as anti-mycobacterial agents.

What is the cost of diagnosis and management of drug resistant tuberculosis in South Africa?

BACKGROUND

Drug-resistant tuberculosis (DR-TB) is undermining TB control in South Africa. However, there are hardly any data about the cost of treating DR-TB in high burden settings despite such information being quintessential for the rational planning and allocation of resources by policy-makers, and to inform future cost-effectiveness analyses.

METHODOLOGY

We analysed the comparative 2011 United States dollar ($) cost of diagnosis and treatment of drug sensitive TB (DS-TB), MDR-TB and XDR-TB, based on National South African TB guidelines, from the perspective of the National TB Program using published clinical outcome data.

PRINCIPAL FINDINGS

Assuming adherence to national DR-TB management guidelines, the per patient cost of XDR-TB was $26,392, four times greater than MDR-TB ($6772), and 103 times greater than drug-sensitive TB ($257). Despite DR-TB comprising only 2.2% of the case burden, it consumed ~32% of the total estimated 2011 national TB budget of US $218 million. 45% and 25% of the DR-TB costs were attributed to anti-TB drugs and hospitalization, respectively. XDR-TB consumed 28% of the total DR-TB diagnosis and treatment costs. Laboratory testing and anti-TB drugs comprised the majority (71%) of MDR-TB costs while hospitalization and anti-TB drug costs comprised the majority (92%) of XDR-TB costs. A decentralized XDR-TB treatment programme could potentially reduce costs by $6930 (26%) per case and reduce the total amount spent on DR-TB by ~7%.

CONCLUSION/SIGNIFICANCE

Although DR-TB forms a very small proportion of the total case burden it consumes a disproportionate and substantial amount of South Africa's total annual TB budget. These data inform rational resource allocation and selection of management strategies for DR-TB in high burden settings.

Antimycobacterial drugs currently in Phase II clinical trials and preclinical phase for tuberculosis treatment

INTRODUCTION

In 2010, about 8.8 million new cases of tuberculosis were recorded and 1.1 million people died of tuberculosis worldwide. Although numbers are in decrease since 2006, tuberculosis still represents a global issue and a major public health threat, due to appearance of multidrug-resistant and extensively drug-resistant tuberculosis cases. Although anti-tuberculosis drugs currently used are effective against tuberculosis, they present however more and more limits, especially in treating complex cases of tuberculosis, increasing therefore the need to develop new tools and approaches to treat tuberculosis today.

AREAS COVERED

In this review, we describe anti-tuberculosis drugs in Phase II clinical trials and in preclinical phase that are likely to play a crucial role in the management of tuberculosis cases in a near future. SQ109, TMC207, nitroimidazoles, and oxazolidinones are currently in Phase II clinical trials while BDM31343, SQ641, CPZEN-45, RBx 8700, DC-159a, and BTZ043 are in preclinical phase.

CONCLUSION

These drugs, alone or in different combinations represent a promising future for the treatment of tuberculosis. Continual conjugative efforts between governments and private organizations worldwide are essential for building new strategies for discovery and the development of new anti-tuberculosis drugs.

Evaluation of pseudopteroxazole and pseudopterosin derivatives against Mycobacterium tuberculosis and other pathogens

Pseudopterosins and pseudopteroxazole are intriguing marine natural products that possess notable antimicrobial activity with a commensurate lack of cytotoxicity. New semi-synthetic pseudopteroxazoles, pseudopteroquinoxalines and pseudopterosin congeners along with simple synthetic mimics of the terpene skeleton were synthesized. In order to build structure-activity relationships, a set of 29 new and previously reported compounds was assessed for invitro antimicrobial and cytotoxic activities. A number of congeners exhibited antimicrobial activity against a range of Gram-positive bacteria including Mycobacteriumtuberculosis H₃₇Rv, with four displaying notable antitubercular activity against both replicating and non-replicating persistent forms of M.tuberculosis. One new semi-synthetic compound, 21-((1H-imidazol-5-yl)methyl)-pseudopteroxazole (7a), was more potent than the natural products pseudopterosin and pseudopteroxazole and exhibited equipotent activity against both replicating and non-replicating persistent forms of M.tuberculosis with a near absence of invitro cytotoxicity. Pseudopteroxazole also exhibited activity against strains of M.tuberculosis H₃₇Rv resistant to six clinically used antibiotics.