Multidrug-resistant tuberculosis

New coumarin linked thiazole derivatives as antimycobacterial agents: Design, synthesis, enoyl acyl carrier protein reductase (InhA) inhibition and molecular modeling

Tuberculosis is a global serious problem that imposes major health, economic and social challenges worldwide. The search for new antitubercular drugs is extremely important which could be achieved via inhibition of different druggable targets. Mycobacterium tuberculosis enoyl acyl carrier protein reductase (InhA) enzyme is essential for the survival of M. tuberculosis. In this investigation, a series of coumarin based thiazole derivatives was synthesized relying on a molecular hybridization approach and was assessed against thewild typeMtb H37Rv and its mutant strain (ΔkatG) via inhibiting InhA enzyme. Among the synthesized derivatives, compounds 2b, 3i and 3j were the most potent against wild type M. tuberculosis with MIC values ranging from 6 to 8 μg/ mL and displayed low cytotoxicity towards mouse fibroblasts at concentrations 8-13 times higher than the MIC values. The three hybrids could also inhibit the growth of ΔkatGmutant strain which is resistant to isoniazid (INH). Compounds 2b and 3j were able to inhibit the growth of mycobacteria inside human macrophages, indicating their ability to penetrate human professional phagocytes. The two derivatives significantly suppress mycobacterial biofilm formation by 10-15 %. The promising target compounds were also assessed for their inhibitory effect against InhA and showed potent effectiveness with IC50 values of 0.737 and 1.494 µM, respectively. Molecular docking studies revealed that the tested compounds occupied the active site of InhA in contact with the NAD+ molecule. The 4-phenylcoumarin aromatic system showed binding interactions within the hydrophobic pocket of the active site. Furthermore, H-bond formation and π -π stacking interactions were also recorded for the promising derivatives.

Identification of new anti-mycobacterial agents based on quinoline-isatin hybrids targeting enoyl acyl carrier protein reductase (InhA)

Tuberculosis (TB) is a global issue that poses a significant economic burden as a result of the ongoing emergence of drug-resistant strains. The urgent requirement for the development of novel antitubercular drugs can be addressed by targeting specific enzymes. One such enzyme, Mycobacterium tuberculosis (MTB) enoyl-acyl carrier protein (enoyl-ACP) reductase (InhA), plays a crucial role in the survival of the MTB bacterium. In this research study, a series of hybrid compounds combining quinolone and isatin were synthesized and assessed for their effectiveness against MTB, as well as their ability to inhibit the activity of the InhA enzyme in this bacterium. Among the compounds tested, 7a and 5g exhibited the most potent inhibitory activity against MTB, with minimum inhibitory concentration (MIC) values of 55 and 62.5 µg/mL, respectively. These compounds were further evaluated for their inhibitory effects on InhA and demonstrated significant activity compared to the reference drug Isoniazid (INH), with IC50 values of 0.35 ± 0.01 and 1.56 ± 0.06 µM, respectively. Molecular docking studies investigated the interactions between compounds 7a and 5g and the target enzyme, revealing hydrophobic contacts with important amino acid residues in the active site. To further confirm the stability of the complexes formed by 5g and 7a with the target enzyme, molecular dynamic simulations were employed, which demonstrated that both compounds 7a and 5g undergo minor structural changes and remain nearly stable throughout the simulated process, as assessed through RMSD, RMSF, and Rg values.

Global prevalence of drug-resistant tuberculosis: a systematic review and meta-analysis

BACKGROUND

Tuberculosis is a bacterial infectious disease, which affects different parts of a human body, mainly lungs and can lead to the patient's death. The aim of this study is to investigate the global prevalence of drug-resistant tuberculosis using a systematic review and meta-analysis.

METHODS

In this study, the PubMed, Scopus, Web of Science, Embase, ScienceDirect and Google Scholar repositories were systematically searched to find studies reporting the global prevalence of drug-resistant tuberculosis. The search did not entail a lower time limit, and articles published up until August 2022 were considered. Random effects model was used to perform the analysis. The heterogeneity of the studies was examined with the I² test. Data analysis was conducted within the Comprehensive Meta-Analysis software.

RESULTS

In the review of 148 studies with a sample size of 318,430 people, the I² index showed high heterogeneity (I² = 99.6), and accordingly random effects method was used to analyze the results. Publication bias was also examined using the Begg and Mazumdar correlation test which indicated the existence of publication bias in the studies (P = 0.008). According to our meta-analysis, the global pooled prevalence of multi-drug resistant TB is 11.6% (95% CI: 9.1-14.5%).

CONCLUSIONS

The global prevalence of drug-resistant tuberculosis was found to be very high, thus health authorities should consider ways to control and manage the disease to prevent a wider spread of tuberculosis and potentially subsequent deaths.

Imidazole-Thiosemicarbazide Derivatives as Potent Anti-Mycobacterium tuberculosis Compounds with Antibiofilm Activity

Mycobacterium tuberculosis (Mtb) is an intracellular pathogenic bacterium and the causative agent of tuberculosis. This disease is one of the most ancient and deadliest bacterial infections, as it poses major health, social and economic challenges at a global level, primarily in low- and middle-income countries. The lack of an effective vaccine, the long and expensive drug therapy, and the rapid spread of drug-resistant strains of Mtb have led to the re-emergence of tuberculosis as a global pandemic. Here, we assessed the in vitro activity of new imidazole-thiosemicarbazide derivatives (ITDs) against Mtb infection and their effects on mycobacterial biofilm formation. Cytotoxicity studies of the new compounds in cell lines and human monocyte-derived macrophages (MDMs) were performed. The anti-Mtb activity of ITDs was evaluated by determining minimal inhibitory concentrations of resazurin, time-kill curves, bacterial intracellular growth and the effect on biofilm formation. Mutation frequency and whole-genome sequencing of mutants that were resistant to ITDs were performed. The antimycobacterial potential of ITDs with the ability to penetrate Mtb-infected human macrophages and significantly inhibit the intracellular growth of tubercle bacilli and suppress Mtb biofilm formation was observed.

Identification and Characterization of Two Defensins from Capsicum annuum Fruits that Exhibit Antimicrobial Activity

Scientific advances have not been enough to combat the growing resistance to antimicrobial medicines. Antimicrobial peptides (AMPs) are effector molecules of the innate immune defense system in plants and could provide an important source of new antimicrobial drugs. The aim of this work was to extract, purify, characterize, and evaluate the antifungal activities present in fractions obtained from Capsicum annum fruits through reversed-phase chromatography. The fractions named F2 and F3 presented the highest inhibitory activity against Candida and Mycobacterium tuberculosis species. In addition, we identified two sequences of AMPs in the F2 and F3 fractions through mass spectrometry that showed similarity to an already well-characterized family of plant defensins. A plasma membrane permeabilization assay demonstrated that the peptides present in F2, F3, and F4 fractions induced changes in the membrane of some yeast strains, culminating in permeabilization. The production of reactive oxygen species was induced by the fractions in some yeast strains. Fractions F2, F3, and F4 also did not show toxicity in macrophage or monocyte cultures. In conclusion, the obtained data demonstrate that the AMPs, especially those present in the fractions F2 and F3, are promising antimicrobial agents that may be useful to enhance the development of new therapeutic agents for the treatment of diseases.

Challenge to treat pre-extensively drug-resistant tuberculosis in a low-income country: A report of 12 cases

Setting: Democratic Republic of the Congo is a high-burden TB country. Its capital, Kinshasa, reports annually about one-third of all MDR-TB cases in the country; thus, pre-XDRTB management is warranted.

Objectives

To describe the main challenges in treating pre- XDR TB in this low resources setting and possible solutions.

Method

This is a retrospective study of all pre-XDR TB patients diagnosed in Kinshasa in 2018. A personalized regimen was applied according to the clinical profile, drug availability, and the Drug susceptibility testing (DST). Treatment was administered by hospitalization during the intensive phase and in ambulatory care in the continuation phase except in emergencies. Monthly follow up included evaluating clinical and bacteriological features, renal and liver functions, QT interval on ECG, and audiometry for those under aminoglycosides.

Results

Among the 236 MDR-TB patients identified in 2018, 14 had pre-XDR. Two died before treatment initiation. Of the remaining 12. 75% were male, 50% were aged 25-44 years, 66.7% had previous anti-tuberculosis treatment, 75% had a body mass index < 18.5 kg/m², and 1 patient was HIV positive. On radiography, all the patients had cavities. The median time from the diagnosis to treatment initiation was 48.5 days (range: 14-105). A favorable outcome occurred in 10 cases (83.3%), one patient died, and anotherwas lost to follow up. Nine (75%) patients reported adverse reactions, which were mild or moderate in 6 cases and severe in 2 cases. The severe reactions were psychosis (1 case) and ototoxicity (1 case).

Conclusion

Successful pre-XDRTB treatment using the new strategy is possible even in a low-income country. The main challenges are diagnosis access, drug availability and follow-up laboratory facilities. These can be included in a global policy review by the NTP to ensure the sustainability of the strategies implemented.

Antibacterial and Antimycobacterial Activity of Crude Extracts, Fractions, and Isolated Compounds From Leaves of Sneezewood, Ptaeroxylon obliquum (Rutaceae)

Ptaeroxylon obliquum (Thunb.) Radlk. (Rutaceae) is traditionally used to treat human and animal diseases in South Africa. In this study, the activity of leaf extracts, fractions, and isolated compounds was determined against nonpathogenic mycobacterial species and nosocomial bacterial pathogens. An acetone leaf extract was partitioned by liquid-liquid fractionation, and obliquumol, a mixture of lupeol and β-amyrin, and eranthin were isolated. Antimicrobial activity was determined using a serial microdilution assay against Mycobacterium smegmatis (American Type Culture Collection [ATCC] 1441), M. bovis (BCG P1172), M. aurum (NCTC 10437), M. fortuitum (ATCC 6841), Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 25922), and Escherichia coli (ATCC 27853). The n-hexane fraction had minimal inhibitory concentration (MIC) values as low as 20 and 40 µg/mL against M. fortuitum and S. aureus, respectively. The chloroform fraction also had promising activity with an MIC value of 80 µg/mL against both P. aeruginosa and M. fortuitum. Obliquumol had excellent activity (MIC 8 µg/mL) against M. fortuitum. Fractionation of the crude extract potentiated the antimicrobial activity of the nonpolar fractions. The isolated compound, obliquumol, had good antimicrobial and excellent antimycobacterial activities. The antimicrobial activity provides some scientific rationale for the use of P. obliquum against infectious diseases and related symptoms. This is the first report on the antibacterial activity of obliquumol.

Use of nanotechnology for infectious disease diagnostics: application in drug resistant tuberculosis

BACKGROUND

The increased transmission of multidrug-resistant (MDR) tuberculosis (TB) poses a challenge to tuberculosis prevention and control in Sri Lanka. Isoniazid (INH) is a key element of the first line anti tuberculosis treatment regimen. Resistance to INH may lead to development of MDR TB. Therefore, early detection of INH resistance is important to curb spread of resistance. Due to the limited availability of rapid molecular methods for detection of drug resistance in Sri Lanka, this study was aimed at developing a simple and rapid gold nanoparticle (AuNP) based lateral flow strip for the simultaneous detection of the most common INH resistance mutation (katG S315 T, 78.6%) and Mycobacterium tuberculosis (MTb).

METHODS

Lateral flow strip was designed on an inert plastic backing layer containing a sample pad, nitrocellulose membrane and an absorption pad. Biotin labeled 4 capture probes which separately conjugated with streptavidin were immobilized on the nitrocellulose. The test sample was prepared by multiplex PCR using primers to amplify codon 315 region of the katG gene and MTb specific IS6110 region. The two detection probes complementary to the 5' end of each amplified fragment was conjugated with gold nanoparticles (20 nm) and coupled with the above amplified PCR products were applied on the sample pad. The hybridization of the amplified target regions to the respective capture probes takes place when the sample moves towards the absorption pad. Positive hybridization is indicated by red colour lines.

RESULTS

The three immobilized capture probes on the strip (for the detection of TB, katG wild type and mutation) were 100 and 96.6% specific and 100 and 92.1% sensitive respectively.

CONCLUSION

The AuNP based lateral flow assay was capable of differentiating the specific mutation and the wild type along with MTb identification within 3 h.

Prevalence of and Factors Influencing Anti-Tuberculosis Treatment Non-Adherence Among Patients with Pulmonary Tuberculosis: A Cross-Sectional Study in Anhui Province, Eastern China

BACKGROUND To assess the non-adherence rate among pulmonary tuberculosis (TB) patients in Anhui Province, eastern China and to explore the influential factors, so as to identify targets for intervention. MATERIAL AND METHODS A total of 339 TB patients were recruited from TB dispensaries in 8 counties of Anhui Province, eastern China using a stratified sampling method. All study subjects were surveyed using a structured questionnaire. Differences between groups involving categorical data were analyzed using the chi-square test. RESULTS Overall, of the 339 patients, 33.63% missed medication. Divorced and widowed patients were more likely to miss medication compared with those who were married or unmarried (P<0.01). Regarding the knowledge related to topics such as transmission route, preventive measures, and suspicious symptoms, the awareness rate in the group with good medication compliance was higher than in the group with poor compliance (P<0.05). We found that compliance was not significantly associated with seeking medical treatment in professional institutions, the national free TB treatment policy, or discrimination (P>0.05). The rate of non-compliance under supervision (26.10%) was lower than that without supervision (64.18%) (P<0.001). CONCLUSIONS The anti-TB treatment non-adherence rate in TB patients is relatively high in Anhui Province, eastern China, and is associated with marital status, annual income, TB knowledge, and medical staff visits.

An in vitro ADME and in vivo Pharmacokinetic Study of Novel TB-Active Decoquinate Derivatives

Tuberculosis (TB) is currently the leading cause of mortality due to an infectious disease, despite the existence of multiple effective first-line and second-line drugs. The current anti-TB regimen requires a prolonged treatment period of around 6 months and is only efficacious against drug-sensitive strains of Mycobacterium tuberculosis (Mtb). With a rise in cases of multi-drug resistant and extensively drug resistant strains of Mtb, newer treatments comprising compounds with novel mechanisms of action are required. Although decoquinate (DQ) is inactive against Mtb, its derivatives are of interest to anti-TB drug discovery because of their potential to permeate the mycobacterial cell wall, Mtb-infected macrophages, and granulomatous lesions by passive diffusion. The compounds also display mechanisms of action which are unlike those of currently used quinolones, potentially displaying activity against new targets. Three such derivatives bearing an alkyl group at N-1 and an amide group at C-3 (RMB 041, -043, and -073) displayed potent in vitro activities against Mtb H37Rv (90% minimum inhibitory concentrations, MIC90 = 1.61, 4.18, and 1.88 μM, respectively) and high selectivity indices (10-25). In this study, we evaluated the drug-like properties (in vitro microsomal stability, microsomal/plasma protein binding, kinetic solubility, lipophilicity, and passive permeability) and pharmacokinetic (PK) parameters of these compounds after intravenous and oral administration to male C57BL/6 mice. The compounds showed markedly improved kinetic solubilities compared to that of the parental DQ and were metabolically stable in vitro. The maximum concentrations reached after oral administration were 5.4 ± 0.40, 5.6 ± 1.40, and 2.0 ± 0.03 μM; elimination half-lives were 23.4 ± 2.50, 6.2 ± 0.80, and 11.6 ± 1.30 h; and bioavailabilities were 21.4 ± 1.0, 22.1 ± 2.2, and 5.9 ± 1.3 for RMB041, -043, and -073, respectively. These compounds therefore display promising drug-like properties, and their PK/toxicity profiles (including long half-lives both in vitro and in vivo) support their potential as candidates for further investigation in animal models of Mtb infection.

Isoniazid Pharmacokinetics in the Presence of Ofloxacin and Norfloxacin Antibiotics

The in vivo effects of norfloxacin (NXC) and ofloxacin (OXC) on isoniazid (INH) pharmacokinetics were investigated in 5 apparently healthy volunteers aged 18-39 years after an informed consent. The study was carried out in 3 phases with an interval drug wash out period of at least 1 week in between the phases. In phase 1 (INH alone), subject received 300 mg (usual adult dose) of INH. In phase 2 (INH + OXC), 300 mg of INH was coadministered with 200 mg of OXC, and in phase 3 (INH + NXC) each received 300 mg of INH together with 400 mg of NXC after 1-week drug wash period. Drugs were taken orally with 350 mL of water after an overnight fast, and the subject fasted 3 hours after drug. Plasma, saliva, and urine concentration of INH were predetermined at zero hour, then hourly until the eighth hour, 12 hours, 24 hours, and finally at 48 hours. The urine samples were further collected at 72 hours after drug(s) administration using validated methods. Various pharmacokinetics parameters were calculated. Various pharmacokinetic parameters of INH significantly differed when administered alone or in combination with OXC or with NXC. The mean saliva to plasma ratio of INH concentration was 0.14. The bioavailability indices of INH in the saliva and plasma were similar in all the groups. NXC and OXC reduced the extent and rate of absorption of INH. The determination of INH levels in saliva may be useful in therapeutic drug monitoring and pharmacokinetic studies.

TB-EFI, a novel 18-Plex microbead-based method for prediction of second-line drugs and ethambutol resistance in Mycobacterium tuberculosis complex

Several diagnostic tests are being developed to detect drug resistance in tuberculosis. In line with previous developments detecting rifampicin and isoniazid resistance using microbead-based systems (spoligoriftyping and TB-SPRINT), we present here an assay called TB-EFI detecting mutations involved in resistance to ethambutol, fluoroquinolones and the three classical injectable drugs (kanamycin, amikacin and capreomycin) in Mycobacterium tuberculosis. The proposed test includes both wild-type and mutant probes for each targeted locus. Basic analysis can be performed manually. An upgraded interpretation is made available in Excel 2016®. Using a reference set of 61 DNA extracts, we show that TB-EFI provides perfect concordance with pyrosequencing. Concordance between genotypic resistance and phenotypic DST was relatively good (72 to 98% concordance), with lower efficiency for fluoroquinolones and ethambutol due to some untargeted mutations. When compared to phenotypical resistance, performances were similar to those obtained with Hain MTBDRsl assay, possibly thanks to the use of automatized processing of data although some mutations involved in fluoroquinolone resistance could not be included. When applied on three uncharacterized sets, phenotype could be predicted for 51% to 98% depending on the setting and the drug investigated, detecting one extensively drug-resistant isolate in each of a Pakistan and a Brazilian set of 91 samples, and 9 XDR among 43 multi-resistant Kazakhstan samples. By allowing high-throughput detection of second-line drugs resistance and of resistance to ethambutol that is often combined to second-line treatments, TB-EFI is a cost-effective assay for large-scale worldwide surveillance of resistant tuberculosis and XDR-TB control.

Host Antimicrobial Peptides: The Promise of New Treatment Strategies against Tuberculosis

Tuberculosis (TB) continues to be a devastating infectious disease and remerges as a global health emergency due to an alarming rise of antimicrobial resistance to its treatment. Despite of the serious effort that has been applied to develop effective antitubercular chemotherapies, the potential of antimicrobial peptides (AMPs) remains underexploited. A large amount of literature is now accessible on the AMP mechanisms of action against a diversity of pathogens; nevertheless, research on their activity on mycobacteria is still scarce. In particular, there is an urgent need to integrate all available interdisciplinary strategies to eradicate extensively drug-resistant Mycobacterium tuberculosis strains. In this context, we should not underestimate our endogenous antimicrobial proteins and peptides as ancient players of the human host defense system. We are confident that novel antibiotics based on human AMPs displaying a rapid and multifaceted mechanism, with reduced toxicity, should significantly contribute to reverse the tide of antimycobacterial drug resistance. In this review, we have provided an up to date perspective of the current research on AMPs to be applied in the fight against TB. A better understanding on the mechanisms of action of human endogenous peptides should ensure the basis for the best guided design of novel antitubercular chemotherapeutics.

Factors associated with tuberculosis treatment outcomes among tuberculosis patients attending tuberculosis treatment centres in 2016-2017 in Mogadishu, Somalia

Introduction

World Health Organization (WHO) reported that tuberculosis (TB) was a major health problem and the second leading cause of mortality globally. An estimated 1.8 million TB deaths were reported in 2015. In Somalia, the average TB incidence was 274 cases per 100,000 people in 2014; prevalence was 513 per 100,000 population; and mortality rate excluding human immune deficiency virus (HIV)/TB co-infection was 64/100,000. In addition, the prevalence rates of multi-drug resistant (MDR)-TB are still high, 5.2% among new cases and 40.7% for retreatment cases. The objective of this study was to determine individual and institutional level factors associated with TB treatment outcomes (TB-TOs) among patients attending TBTCs in Mogadishu.

Methods

The study design was cross-sectional, using quantitative and qualitative methods. Data was collected using interviewer administered semi-structured questionnaires and key in-depth interviews in 2016/2017. Qualitative data was coded using NVIVO8 and quantitative data analyzed using descriptive and inferential statistics at 95% confidence interval using SPSS20 software.

Results

The study used a sample of 385 TB patients. There were 315(81.8%) successful TB-TOs. Individual level factors-marital status, education level, HIV status, treatment category and knowledge on TB influenced TB-TOs (p-value < 0.05). Being married, educated, HIV-negative, new treatment case and knowledgeable on TB increased odds of successful TB-TOs (OR > 0, p value < 0.05) compared to other patients. TBTCs factors did not influence TB-TOs (p-value > 0.05).

Conclusion

TB-TOs were mainly affected by patient individual factors. There was need for patient education on TB management and treatment; and improved patient-health provider relationship.

Plant-derived antimicrobials to fight against multi-drug-resistant human pathogens

Antibiotic resistance is becoming a pivotal concern for public health that has accelerated the search for new antimicrobial molecules from nature. Numbers of human pathogens have inevitably evolved to become resistant to various currently available drugs causing considerable mortality and morbidity worldwide. It is apparent that novel antibiotics are urgently warranted to combat these life-threatening pathogens. In recent years, there have been an increasing number of studies to discover new bioactive compounds from plant origin with the hope to control antibiotic-resistant bacteria. This review attempts to focus and record the plant-derived compounds and plant extracts against multi-drug-resistant (MDR) pathogens including methicillin-resistant Staphylococcus aureus (MRSA), MDR-Mycobacterium tuberculosis and malarial parasites Plasmodium spp. reported between 2005 and 2015. During this period, a total of 110 purified compounds and 60 plant extracts were obtained from 112 different plants. The plants reviewed in this study belong to 70 different families reported from 36 countries around the world. The present review also discusses the drug resistance in bacteria and emphasizes the urge for new drugs.

Risk factors that may be driving the emergence of drug resistance in tuberculosis patients treated in Yangon, Myanmar

Background

The majority of new tuberculosis cases emerging every year occur in low and middle-income countries where public health systems are often characterised by weak infrastructure and inadequate resources. This study investigates healthcare seeking behaviour, knowledge and treatment of tuberculosis patients in Myanmar—which is facing an acute drug-resistant tuberculosis epidemic—and identifies factors that may increase the risk of emergence of drug-resistant tuberculosis.

Methods

We randomly selected adult smear-positive pulmonary tuberculosis patients diagnosed between September 2014 and March 2015 at ten public township health centres in Yangon, the largest city in Myanmar. Data on patients’ healthcare seeking behaviour, treatment at the township health centres, co-morbidities and knowledge was collected through patient interviews and extraction from hospital records. A retrospective descriptive cross-sectional analysis was conducted.

Results

Of 404 TB patients selected to participate in the study, 11 had died since diagnosis, resulting in 393 patients being included in the final analysis. Results indicate that a high proportion of patients (16%; 95% CI = 13–20) did not have a treatment supporter assigned to improve adherence to medication, with men being more likely to have no treatment supporter assigned. Use of private healthcare providers was very common; 59% (54–64) and 30.3% (25.9–35.0) of patients reported first seeking care at private clinics and pharmacies respectively. We found that 8% (6–11) of tuberculosis patients had confirmed diabetes. Most patients had some knowledge about tuberculosis transmission and the consequences of missing treatment. However, 5% (3–8) stated that they miss taking tuberculosis medicines at least weekly, and patients with no knowledge of consequences of missing treatment were more likely to miss doses.

Conclusions

This study analysed healthcare seeking behaviour and treatment related practices of tuberculosis patients being managed under operational conditions in a fragile health system. Findings indicate that ensuring that treatment adherence support is arranged for all patients, monitoring of response to treatment among the high proportion of tuberculosis patients with diabetes and engagement with private healthcare providers could be strategies addressed to reduce the risk of emergence of drug-resistant tuberculosis.

Genomic Insight into Mechanisms of Reversion of Antibiotic Resistance in Multidrug Resistant Mycobacterium tuberculosis Induced by a Nanomolecular Iodine-Containing Complex FS-1

Drug induced reversion of antibiotic resistance is a promising way to combat multidrug resistant infections. However, lacking knowledge of mechanisms of drug resistance reversion impedes employing this approach in medicinal therapies. Induction of antibiotic resistance reversion by a new anti-tuberculosis drug FS-1 has been reported. FS-1 was used in this work in combination with standard anti-tuberculosis antibiotics in an experiment on laboratory guinea pigs infected with an extensively drug resistant (XDR) strain Mycobacterium tuberculosis SCAID 187.0. During the experimental trial, genetic changes in the population were analyzed by sequencing of M. tuberculosis isolates followed by variant calling. In total 11 isolates obtained from different groups of infected animals at different stages of disease development and treatment were sequenced. It was found that despite the selective pressure of antibiotics, FS-1 caused a counter-selection of drug resistant variants that speeded up the recovery of the infected animals from XDR tuberculosis. Drug resistance mutations reported in the genome of the initial strain remained intact in more sensitive isolates obtained in this experiment. Variant calling in the sequenced genomes revealed that the drug resistance reversion could be associated with a general increase in genetic heterogeneity of the population of M. tuberculosis. Accumulation of mutations in PpsA and PpsE subunits of phenolpthiocerol polyketide synthase was observed in the isolates treated with FS-1 that may indicate an increase of persisting variants in the population. It was hypothesized that FS-1 caused an active counter-selection of drug resistant variants from the population by aggravating the cumulated fitness cost of the drug resistance mutations. Action of FS-1 on drug resistant bacteria exemplified the theoretically predicted induced synergy mechanism of drug resistance reversion. An experimental model to study the drug resistance reversion phenomenon is hereby introduced.

The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis

Global tuberculosis incidence has declined marginally over the past decade, and tuberculosis remains out of control in several parts of the world including Africa and Asia. Although tuberculosis control has been effective in some regions of the world, these gains are threatened by the increasing burden of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. XDR tuberculosis has evolved in several tuberculosis-endemic countries to drug-incurable or programmatically incurable tuberculosis (totally drug-resistant tuberculosis). This poses several challenges similar to those encountered in the pre-chemotherapy era, including the inability to cure tuberculosis, high mortality, and the need for alternative methods to prevent disease transmission. This phenomenon mirrors the worldwide increase in antimicrobial resistance and the emergence of other MDR pathogens, such as malaria, HIV, and Gram-negative bacteria. MDR and XDR tuberculosis are associated with high morbidity and substantial mortality, are a threat to health-care workers, prohibitively expensive to treat, and are therefore a serious public health problem. In this Commission, we examine several aspects of drug-resistant tuberculosis. The traditional view that acquired resistance to antituberculous drugs is driven by poor compliance and programmatic failure is now being questioned, and several lines of evidence suggest that alternative mechanisms-including pharmacokinetic variability, induction of efflux pumps that transport the drug out of cells, and suboptimal drug penetration into tuberculosis lesions-are likely crucial to the pathogenesis of drug-resistant tuberculosis. These factors have implications for the design of new interventions, drug delivery and dosing mechanisms, and public health policy. We discuss epidemiology and transmission dynamics, including new insights into the fundamental biology of transmission, and we review the utility of newer diagnostic tools, including molecular tests and next-generation whole-genome sequencing, and their potential for clinical effectiveness. Relevant research priorities are highlighted, including optimal medical and surgical management, the role of newer and repurposed drugs (including bedaquiline, delamanid, and linezolid), pharmacokinetic and pharmacodynamic considerations, preventive strategies (such as prophylaxis in MDR and XDR contacts), palliative and patient-orientated care aspects, and medicolegal and ethical issues.

Transmission Electron Microscopy of XDR Mycobacterium tuberculosis Isolates Grown on High Dose of Ofloxacin

The aim of the study was to investigate behavior of resistant Mycobacterium tuberculosis (MTB) isolates under a high dose of ofloxacin and its morphological changes. 19 extensively drug resistant (XDR) clinical isolates of MTB were grown on Löwenstein–Jensen medium containing progressively increasing concentrations of ofloxacin (2, 4, 8, 16, 32 mg/L). Ultra-structure analyses of resistant isolates grown on ofloxacin were conducted by transmission electron microscopy (TEM). Fixation was carried out by 4% glutaraldehyde in 0.1 M sodium cacodylate buffer on 300 mesh carbon formvar copper grid. The samples were negatively stained with uranium acetate suspension. All 19 XDR MTB isolates were grown and formed colonies successfully on 2, 4, 8 mg/L, seven isolates on 16 mg/L, and four isolates on 32 mg/L ofloxacin. Morphological changes and unusual forms were detected in 8, 16 and 32 mg/L ofloxacin at 43%, 76.5% and 81% of cells, respectively. Swollen form (protoplast like), ghost-like cell, degraded forms, and in a few cases, detached cytoplasm from cell wall were clearly detected in high drug concentrations in comparison to control. Changes in morphology were increased with increasing ofloxacin concentrations (p < 0.05). Some XDR isolates could be successfully grown on high doses of ofloxacin (32 mg/L), but with changes in morphology. It was concluded that several magnitudes of the drug doses could not prevent growth of drug resistant forms.

An audiological profile of patients infected with multi-drug resistant tuberculosis at a district hospital in KwaZulu-Natal

BACKGROUND

The increased incidence of multi-drug-resistant tuberculosis (MDR-TB) and the consequent use of aminoglycosides with their ototoxic potential necessitate a better understanding of the audiological pattern of infected patients.

OBJECTIVE

To describe the occurrence and nature of hearing loss in patients with MDR-TB receiving aminoglycosides over a period of 6 months.

METHODS

Baseline and five consecutive monthly audiological assessments were conducted on 52 adults at a hospital in KwaZulu-Natal. A longitudinal descriptive study was implemented. A conventional audiological test battery, extended high frequency audiometry and otoacoustic emission testing were conducted. Data were analysed using SPSS version 19 statistical software package.

RESULTS

Decreased hearing was the most common audiological symptom experienced. Bilateral sensorineural hearing loss was predominant. Ototoxic hearing loss was noted in 27 participants (52%) in 1 month post-treatment. Hearing loss progressed from mild to moderate at post-treatment one, to moderate to severe at post-treatment three and severe to profound at post-treatment five. Changes in hearing function were noted in 52 participants (100%) by post-treatment five. High and ultra-high frequencies were most affected. Speech discrimination scores deteriorated over time. The number of patients with absent distortion product otoacoustic emissions increased over treatment duration.

CONCLUSION

The greatest effects were observed in the high frequencies before manifesting in the lower frequencies. This highlights the importance of inclusion of high frequency audiometry in the early detection of ototoxicity which can go undiagnosed with traditional audiometry. The high prevalence of hearing loss has implications for the provision of audiological service to this patient population.

Mycobacterium tuberculosis AtsG (Rv0296c), GlmU (Rv1018c) and SahH (Rv3248c) Proteins Function as the Human IL-8-Binding Effectors and Contribute to Pathogen Entry into Human Neutrophils

Mycobacterium tuberculosis is an extremely successful intracellular pathogen that has evolved a broad spectrum of pathogenic mechanisms that enable its manipulation of host defense elements and its survival in the hostile environment inside phagocytes. Cellular influx into the site of mycobacterial entry is mediated by a variety of chemokines, including interleukin-8 (IL-8), and the innate cytokine network is critical for the development of an adaptive immune response and infection control. Using affinity chromatography, liquid chromatography electrospray ionization tandem mass spectrometry and surface plasmon resonance techniques, we identified M. tuberculosis AtsG arylsulphatase, bifunctional glucosamine-1-phosphate acetyltransferase and N-acetylglucosamine-1-phosphate uridyl transferase (GlmU) and S-adenosyl-L-homocysteine hydrolase (SahH) as the pathogen proteins that bind to human IL-8. The interactions of all of the identified proteins (AtsG, GlmU and SahH) with IL-8 were characterized by high binding affinity with K_D values of 6.83x10^-6 M, 5.24x10^-6 M and 7.14x10^-10 M, respectively. Furthermore, the construction of Mtb mutant strains overproducing AtsG, GlmU or SahH allowed determination of the contribution of these proteins to mycobacterial entry into human neutrophils. The significantly increased number of intracellularly located bacilli of the overproducing M. tuberculosis mutant strains compared with those of “wild-type” M. tuberculosis and the binding interaction of AtsG, GlmU and SahH proteins with human IL-8 may indicate that these proteins participate in the modulation of the early events of infection with tubercle bacilli and could affect pathogen attachment to target cells.

Effect of ofloxacin and norfloxacin on rifampicin pharmacokinetics in man

The in vivo effects of norfloxacin (NXC) and ofloxacin (OXC) on rifampicin (RIF) pharmacokinetics were investigated in 5 apparently healthy volunteers aged 18-39 years after informed consent. The study was carried out in 3 phases with an interval drug washout period of at least 1 week in between the phases. In phase 1 (RIF alone), the subject received 600 mg of RIF. In phase 2 (RIF + OXC), 600 mg of RIF was coadministered with 200 mg of OXC. In phase 3 (RIF + NXC), each subject received 600 mg of RIF together with 400 mg of NXC after 1 week drug washout period. Drugs were taken orally with 350 mL of water after an overnight fast, and the subjects fasted 3 hours after the administration of drug. Plasma, saliva, and urine concentration of RIF were predetermined at 0 hour and then hourly until the 8th, 12th, 24th, and 48th hour. The urine samples were further collected at 72 hours after drug(s) administration using validated methods. Various pharmacokinetics parameters were calculated. NXC reduced the extent and rate of absorption of RIF. Various pharmacokinetic parameters of RIF significantly differ when administered alone or in combination with OXC and NXC. The mean saliva to plasma ratio of RIF concentration was approximately 0.15. The bioavailability indices of RIF in the saliva and plasma were similar in all the groups. Several pharmacokinetic parameters could be calculated using different body fluid concentrations of RIF. The determination of RIF levels in saliva may be useful in therapeutic drug monitoring and pharmacokinetic studies.

Community-based care vs. centralised hospitalisation for MDR-TB patients, KwaZulu-Natal, South Africa

SETTING

KwaZulu-Natal, South Africa, a predominantly rural province with a high burden of tuberculosis (TB), multidrug-resistant TB (MDR-TB) and human immunodeficiency virus (HIV) infection.

OBJECTIVE

To determine the most effective care model by comparing MDR-TB treatment outcomes at community-based sites with traditional care at a central, specialised hospital.

DESIGN

A non-randomised observational prospective cohort study comparing community-based and centralised care. Patients at community-based sites were closer to home and had easier access to care, and home-based care was available from treatment initiation.

RESULTS

Four community-based sites treated 736 patients, while 813 were treated at the centralised hospital (total = 1549 patients). Overall, 75% were HIV co-infected (community: 76% vs. hospitalised: 73%, P = 0.45) and 86% received antiretroviral therapy (community: 91% vs. hospitalised: 82%, P = 0.22). On multivariate analysis, MDR-TB patients were more likely to have a successful treatment outcome if they were treated at a community-based site (adjusted OR 1.43, P = 0.01). However, outcomes at the four community-based sites were heterogeneous, with Site 1 demonstrating that home-based care was associated with an increased treatment success of 72% compared with success rates of 52-60% at the other three sites.

CONCLUSION

Community-based care for MDR-TB patients was more effective than care in a central, specialised hospital. Home-based care further increased treatment success.

Antibacterial activities of the methanol extracts, fractions and compounds from Fagara tessmannii

ETHNOPHARMACOLOGICAL RELEVANCE

Fagara tessmannii is a shrub of the African rainforests used to treat bacterial infections, cancers, swellings and inflammation. In the present study, the methanol extract from the leaves (FTL), bark (FTB), and roots (FTR) of this plant as well as fractions (FTR1-5) and compounds isolated from FTR namely β-sitosterol-3-O-β-d-glucopyranoside (1), nitidine chloride (2) and buesgenine (3), were tested for their antimicrobial activities against a panel of Gram-negative bacteria including multidrug resistant (MDR) phenotypes.

MATERIALS AND METHODS

The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; Column chromatography was used for the fractionation and purification of the roots extract whilst the chemical structures of compounds were determined using spectroscopic techniques.

RESULTS

Results of the MIC determinations indicated that the crude extracts from the roots as well as fraction FTRa4 were active on all the 26 tested bacterial strains. MIC values below 100µg/mL were obtained with roots, leaves and bark extract respectively against 30.8%, 15.4% and 11.5% tested bacteria. The lowest MIC value below of 8µg/mL was obtained with extract from the roots against Escherichia coli MC100 strain. The lowest MIC value of 4µg/mL was also obtained with compound 3 against E. coli AG102 and Klebsiella pneumoniae ATCC11296 CONCLUSIONS: The present study demonstrates that F. tessmannii is a potential source of antimicrobial drugs to fight against MDR bacteria. Benzophenanthrine alkaloids 2 and 3 are the main antibacterial consituents of the roots of the plant.

Risk factors for multidrug resistant tuberculosis patients in Amhara National Regional State

BACKGROUND

Multidrug resistant tuberculosis(MDR-TB) is becoming a major threat to tuberculosis control programs in Ethiopia.

OBJECTIVES

To determine risk factors of MDR-TB patients in Amhara National Regional State, Ethiopia.

METHODS

Case-control study was conducted from May 2013 to January 2014. Resistance to rifampicin and isoniazid were done molecularly using line probe assay. TB patients infected with MDR-M.tuberculosis and non MDR-M.tuberculosis strain were considered as cases and controls, respectively. Data was collected using structured questionnaire with face to face interview. Patients' clinical record review was also done.Multivariate analysis was computed to determine the risk factors of MDR-TB.

RESULTS

A total of 153 MDR-TB and equal number of non MDR-TB patients' participated in the study. Patients who had TB treatment failure (AOR=13.5,CI=2.69-70), cavitations on chest x-ray (AOR=1.9,CI=1.1-3.38) and contact with MDR-TB patients (AOR=1.4,CI=0.19-0.39) were more likely to be MDR-TB patients. Low monthly income (AOR=1.1,CI=0.34-0.47),alcohol consumption (AOR=1.5,CI=0.2-0.98) and young age (AOR=2.9,CI=1.07-7.68) were the other risk factors of MDR-TB.

CONCLUSIONS

TB treatment failure, cavitation on chest X-ray, contact with MDR-TB patients and low socioeconomic status were important risk factors for development of MDR-TB. Therefore, strict adherence to directly observed therapy, appropriate management of TB patients and advice on the value of nutrients are helpful to control the spreading of MDR-TB.

The treatment journey of a patient with multidrug-resistant tuberculosis in South Africa: is it patient-centred?

To improve the treatment of patients co-infected with multidrug-resistant tuberculosis (MDR-TB) and the human immunodeficiency virus, we measured the relationship between treatment outcomes and hospital performance at four decentralised MDR-TB sites in South Africa. We describe hospital performance from the patient's perspective by the use of a graphic that visually represents a patient's treatment journey. The graphic was used to report study findings to study sites and as a catalyst for a quality improvement process.

Association between health systems performance and treatment outcomes in patients co-infected with MDR-TB and HIV in KwaZulu-Natal, South Africa: implications for TB programmes

OBJECTIVE

To improve the treatment of MDR-TB and HIV co-infected patients, we investigated the relationship between health system performance and patient treatment outcomes at 4 decentralised MDR-TB sites.

METHODS

In this mixed methods case study which included prospective comparative data, we measured health system performance using a framework of domains comprising key health service components. Using Pearson Product Moment Correlation coefficients we quantified the direction and magnitude of the association between health system performance and MDR-TB treatment outcomes. Qualitative data from participant observation and interviews analysed using systematic text condensation (STC) complemented our quantitative findings.

FINDINGS

We found significant differences in treatment outcomes across the sites with successful outcomes varying from 72% at Site 1 to 52% at Site 4 (p<0.01). Health systems performance scores also varied considerably across the sites. Our findings suggest there is a correlation between treatment outcomes and overall health system performance which is significant (r = 0.99, p<0.01), with Site 1 having the highest number of successful treatment outcomes and the highest health system performance. Although the 'integration' domain, which measured integration of MDR-TB services into existing services appeared to have the strongest association with successful treatment outcomes (r = 0.99, p<0.01), qualitative data indicated that the 'context' domain influenced the other domains.

CONCLUSION

We suggest that there is an association between treatment outcomes and health system performance. The chance of treatment success is greater if decentralised MDR-TB services are integrated into existing services. To optimise successful treatment outcomes, regular monitoring and support are needed at a district, facility and individual level to ensure the local context is supportive of new programmes and implementation is according to guidelines.

Biochemical characterization of Mycobacterium tuberculosis IMP dehydrogenase: kinetic mechanism, metal activation and evidence of a cooperative system

Proposed kinetic mechanism forMtIMPDH in the presence of K⁺.

In vitro anti-mycobacterial activity of nine medicinal plants used by ethnic groups in Sonora, Mexico

Background

Sonoran ethnic groups (Yaquis, Mayos, Seris, Guarijíos, Pimas, Kikapúes and Pápagos) use mainly herbal based preparations as their first line of medicinal treatment. Among the plants used are those with anti-tuberculosis properties; however, no formal research is available.

Methods

Organic extracts were obtained from nine medicinal plants traditionally used by Sonoran ethnic groups to treat different kinds of diseases; three of them are mainly used to treat tuberculosis. All of the extracts were tested against Mycobacterium tuberculosis H37Rv using the Alamar Blue redox bioassay.

Results

Methanolic extracts from Ambrosia confertiflora, Ambrosia ambrosioides and Guaiacum coulteri showed minimal inhibitory concentration (MIC) values of 200, 790 and 1000 μg/mL, respectively, whereas no effect was observed with the rest of the methanolic extracts at the concentrations tested. Chloroform, dichloromethane, and ethyl acetate extracts from Ambrosia confertiflora showed a MIC of 90, 120 and 160 μg/mL, respectively.

Conclusions

A. confertiflora and A. ambrosioides showed the best anti-mycobacterial activity in vitro. The activity of Guaiacum coulteri is consistent with the traditional use by Sonoran ethnic groups as anti-tuberculosis agent.

For these reasons, it is important to investigate a broader spectrum of medicinal plants in order to find compounds active against Mycobacterium tuberculosis.

Risk factors associated with default from multi- and extensively drug-resistant tuberculosis treatment, Uzbekistan: a retrospective cohort analysis

Background

The Médecins Sans Frontières project of Uzbekistan has provided multidrug-resistant tuberculosis treatment in the Karakalpakstan region since 2003. Rates of default from treatment have been high, despite psychosocial support, increasing particularly since programme scale-up in 2007. We aimed to determine factors associated with default in multi- and extensively drug-resistant tuberculosis patients who started treatment between 2003 and 2008 and thus had finished approximately 2 years of treatment by the end of 2010.

Methods

A retrospective cohort analysis of multi- and extensively drug-resistant tuberculosis patients enrolled in treatment between 2003 and 2008 compared baseline demographic characteristics and possible risk factors for default. Default was defined as missing ≥60 consecutive days of treatment (all drugs). Data were routinely collected during treatment and entered in a database. Potential risk factors for default were assessed in univariate analysis using chi-square test and in multivariate analysis with logistic regression.

Results

20% (142/710) of patients defaulted after a median of 6 months treatment (IQR 2.6–9.9). Factors associated with default included severity of resistance patterns (pre-extensively drug-resistant/extensively drug-resistant tuberculosis adjusted odds ratio 0.52, 95%CI: 0.31–0.86), previous default (2.38, 1.09–5.24) and age >45 years (1.77, 1.10–2.87). The default rate was 14% (42/294) for patients enrolled 2003–2006 and 24% (100/416) for 2007–2008 enrolments (p = 0.001).

Conclusions

Default from treatment was high and increased with programme scale-up. It is essential to ensure scale-up of treatment is accompanied with scale-up of staff and patient support. A successful first course of tuberculosis treatment is important; patients who had previously defaulted were at increased risk of default and death. The protective effect of severe resistance profiles suggests that understanding disease severity or fear may motivate against default. Targeted health education and support for at-risk patients after 5 months of treatment when many begin to feel better may decrease default.

Adverse events in an integrated home-based treatment program for MDR-TB and HIV in KwaZulu-Natal, South Africa

Most patients with multidrug-resistant tuberculosis (MDR-TB) in South Africa are HIV-infected, but the safety and tolerability of cotreatment are unknown. The authors reviewed all adverse events (AEs) for patients with MDR-TB in a home-based treatment program in rural KwaZulu-Natal. Of 91 MDR-TB patients, 74 (81%) were HIV-positive and receiving antiretroviral therapy. AEs were common, but most were mild and did not require therapy modification. The most common severe AEs were hypothyroidism (36%) and psychosis (5%). Patients receiving concurrent antiretroviral therapy did not experience AEs more frequently than those on MDR-TB therapy alone. Concurrent treatment for MDR-TB/HIV can be safely administered in a home-based care setting.

Tuberculosis-spoligo-rifampin-isoniazid typing: an all-in-one assay technique for surveillance and control of multidrug-resistant tuberculosis on Luminex devices

As a follow-up of the "spoligoriftyping" development, we present here an extension of this technique which includes the detection of isoniazid resistance-associated mutations in a new 59-plex assay, i.e., tuberculosis-spoligo-rifampin-isoniazid typing (TB-SPRINT), running on microbead-based multiplexed systems. This assay improves the synergy between clinical microbiology and epidemiology by providing (i) mutation-based prediction of drug resistance profiles for patient treatment and (ii) genotyping data for tuberculosis (TB) surveillance. This third-generation microbead-based high-throughput assay for TB runs on the Luminex 200 system and on the recently launched MagPix system (Luminex, Austin, TX). Spoligotyping patterns obtained by the TB-SPRINT method were 100% (n = 85 isolates; 3,655/3,655 spoligotype data points) concordant with those obtained by microbead-based and membrane-based spoligotyping. Genetic drug susceptibility typing provided by the TB-SPRINT method was 100% concordant with resistance locus sequencing (n = 162 for rpoB gene sequencing and n = 76 for katG and inhA sequencing). Considering phenotypic drug susceptibility testing (DST) as the reference method, the sensitivity and specificity of TB-SPRINT regarding Mycobacterium tuberculosis complex (n = 162 isolates) rifampin resistance were both 100%, and those for isoniazid resistance were 90.4% (95% confidence interval, 85 to 95%) and 100%, respectively. Used routinely in national TB reference and specialized laboratories, the TB-SPRINT assay should simultaneously improve personalized medicine and epidemiological surveillance of multidrug-resistant (MDR) TB. This assay is expected to play an emerging role in public health in countries with heavy burdens of MDR TB and/or HIV/TB coinfection. Application of this assay directly to biological samples, as well as development for extensively drug-resistant (XDR) TB detection by inclusion of second-line antituberculosis drug-associated mutations, is under development. With bioinformatical methods and data mining to reduce the number of targets to the most informative ones, locally adapted formats of this technique can easily be developed everywhere.

Chemistry and pharmacology of 4-hydroxylonchocarpin: a review

4-hydroxylonchocarpin (LCP) or 2',4-dihydroxy-3',4'-(2,2-dimethylchromene) chalcone is a chalcone of the class flavonoid, with a molecular weight of 322 g/mol mostly isolated in the family Moraceae and Leguminosae. LCP was reported to have a variety of pharmacological activities such as antibacterial, antifungal, anticancer, anti-reverse transcriptase, antitubercular, antimalarial, anti-inflammatory, ornitnine decarboxylase activity and antioxidant. The hemisynthesis of the compound has been described. The present review was undertaken to bring out together the knowledge on LCP, and can serve as the start point for future research and valorization accomplishments.

Antibacterial activities of the extracts, fractions and compounds from Dioscorea bulbifera

Background

Dioscorea bulbifera is an African medicinal plant used to treat microbial infections. In the present study, the methanol extract, fractions (DBB1 and DBB2) and six compounds isolated from the bulbils of D. bulbifera, namely bafoudiosbulbins A (1), B (2), C (3), F (4), G (5) and 2,7-dihydroxy-4-methoxyphenanthrene (6), were tested for their antimicrobial activities against Mycobacteria and Gram-negative bacteria involving multidrug resistant (MDR) phenotypes expressing active efflux pumps.

Methods

The microplate alamar blue assay (MABA) and the broth microdilution methods were used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples.

Results

The results of the MIC determinations indicated that when tested alone, the crude extract, fractions DBB1 and DBB2 as well as compounds 2 to 5 were able to prevent the growth of all the fifteen studied microorganisms, within the concentration range of 8 to 256 μg/mL. The lowest MIC value for the methanol extract and fractions (16 μg/mL) was obtained with DBB1 and DBB2 on E, coli AG100A and DBB2 on Mycobacterium tuberculosis MTCS2. The lowest value for individual compounds (8 μg/mL) was recorded with compound 3 on M. smegmatis and M. tuberculosis ATCC and MTCS2 strains respectively. The activity of the samples on many MDR bacteria such as Enterobacter aerogenes EA289, CM64, Klebsiella pneumoniae KP63 and Pseudomonas aeruginosa PA124 was better than that of chloramphenicol. When tested in the presence of the efflux pump inhibitor against MDR Gram-negative bacteria, the activity of most of the samples increased. MBC values not greater than 512 μg/mL were recorded on all studied microorganisms with fraction DBB2 and compounds 2 to 5.

Conclusions

The overall results of the present investigation provided evidence that the crude extract D. bulbifera as well as some of the compounds and mostly compounds 3 could be considered as potential antimicrobial drugs to fight against MDR bacteria.

Antimicrobial activities of the methanol extract and compounds from the twigs of Dorstenia mannii (Moraceae)

BACKGROUND

Dorstenia mannii (Moraceae) is a medicinal herb used traditionally for the treatment of many diseases. In the present study, the methanol extract of D. mannii and nine of its isolated compounds, namely dorsmanin A (1), B (2), C (3), D (4), E (6), F (7), G (8) dorsmanin I (9) and 6,8-diprenyleriodictyol (5), were tested for their antimicrobial activities against yeast, Mycobacteria and Gram-negative bacteria.

METHODS

The microplate alamar blue assay (MABA) and the broth microdilution method were used to determine the minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) of the above extract and compounds on a panel of bacterial species.

RESULTS

The results of the MIC determinations demonstrated that the methanol extract as well as compounds 3 and 8 were able to prevent the growth of all the fourteen studied microorganisms within the concentration range of 4 to 1024 μg/ml. The lowest MIC value for the methanol extract (64 μg/ml) was obtained on Candida albicans. The lowest value for individual compounds (4 μg/ml) was recorded with compounds 3 on Pseudomonas aeruginosa PA01 and 7 on Eschericia coli ATCC strain. The MIC values recorded with compounds 3 on P. aeruginosa PA01, 6 on C. albicans,7 on P. aeruginosa PA01 and K. pneumoniae ATCC strain and C. albicans,and 8 on P. aeruginosa PA01, PA124, P. stuartii, M. tuberculosis MTCS1 were lower than or equal to those of the reference drugs. MMC values not greater than 1024 μg/ml were recorded on all studied microorganisms with compounds 3 and 8.

CONCLUSION

The overall results of the present investigation provided evidence that the crude extract of D. mannii as well as some of its compounds such compounds 3 and 8 could be a potential source of natural antimicrobial products.

Risk factors for mortality among MDR- and XDR-TB patients in a high HIV prevalence setting

SETTING

Recent studies suggest that the prevalence of drug-resistant tuberculosis (TB) in sub-Saharan Africa may be rising. This is of concern, as human immunodeficiency virus (HIV) co-infection in multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB has been associated with exceedingly high mortality rates.

OBJECTIVE

To identify risk factors associated with mortality in MDR- and XDR-TB patients co-infected with HIV in South Africa.

DESIGN

Case-control study of patients who died of all causes within 2 years of diagnosis with MDR- or XDR-TB.

RESULTS

Among 123 MDR-TB patients, 78 (63%) died following diagnosis. CD4 count ≤ 50 (HR 4.64, P = 0.01) and 51-200 cells/mm(3) (HR 4.17, P = 0.008) were the strongest independent risk factors for mortality. Among 139 XDR-TB patients, 111 (80%) died. CD4 count ≤ 50 cells/mm(3) (HR 4.46, P = 0.01) and resistance to all six drugs tested (HR 2.54, P = 0.04) were the principal risk factors. Use of antiretroviral therapy (ART) was protective (HR 0.34, P = 0.009).

CONCLUSIONS

Mortality due to MDR- and XDR-TB was associated with greater degree of immunosuppression and drug resistance. Efforts to reduce mortality must focus on preventing the amplification of resistance by strengthening TB treatment programs, as well as reducing the pool of immunosuppressed HIV-infected patients through aggressive HIV testing and ART initiation.

Drug-resistant tuberculosis--current dilemmas, unanswered questions, challenges, and priority needs

Tuberculosis was declared a global emergency by the World Health Organization (WHO) in 1993. Following the declaration and the promotion in 1995 of directly observed treatment short course (DOTS), a cost-effective strategy to contain the tuberculosis epidemic, nearly 7 million lives have been saved compared with the pre-DOTS era, high cure rates have been achieved in most countries worldwide, and the global incidence of tuberculosis has been in a slow decline since the early 2000s. However, the emergence and spread of multidrug-resistant (MDR) tuberculosis, extensively drug-resistant (XDR) tuberculosis, and more recently, totally drug-resistant tuberculosis pose a threat to global tuberculosis control. Multidrug-resistant tuberculosis is a man-made problem. Laboratory facilities for drug susceptibility testing are inadequate in most tuberculosis-endemic countries, especially in Africa; thus diagnosis is missed, routine surveillance is not implemented, and the actual numbers of global drug-resistant tuberculosis cases have yet to be estimated. This exposes an ominous situation and reveals an urgent need for commitment by national programs to health system improvement because the response to MDR tuberculosis requires strong health services in general. Multidrug-resistant tuberculosis and XDR tuberculosis greatly complicate patient management within resource-poor national tuberculosis programs, reducing treatment efficacy and increasing the cost of treatment to the extent that it could bankrupt healthcare financing in tuberculosis-endemic areas. Why, despite nearly 20 years of WHO-promoted activity and >12 years of MDR tuberculosis-specific activity, has the country response to the drug-resistant tuberculosis epidemic been so ineffectual? The current dilemmas, unanswered questions, operational issues, challenges, and priority needs for global drug resistance screening and surveillance, improved treatment regimens, and management of outcomes and prevention of DR tuberculosis are discussed.

Antiprotozoal and Antimycobacterial Activities of Pure Compounds from Aristolochia elegans Rhizomes

We analyzed the antimycobacterial activity of the hexane extract of rhizomes from Aristolochia elegans. Some compounds of this extract were purified and tested against a group of drug-resistant Mycobacterium tuberculosis strains. We also evaluated their antiprotozoal activities. The hexane extract was active against M. tuberculosis H37Rv at a MIC = 100 μg mL(-1); the pure compounds eupomatenoid-1, fargesin, and (8R,8'R,9R)-cubebin were active against M. tuberculosis H37Rv (MIC = 50 μg mL(-1)), while fargesin presented activity against three monoresistant strains of M. tuberculosis H37Rv and a MDR clinical isolate of M. tuberculosis (MIC < 50 μg mL(-1)). Both the extract and eupomatenoid-1 were very active against E. histolytica and G. lamblia (IC(50) < 0.624 μg mL(-1)); in contrast, fargesin and (8R,8'R,9R)-cubebin were moderately active (IC(50) < 275 μg mL(-1)). In this context, two compounds responsible for the antimycobacterial presented by A. elegans are fargesin and cubebin, although others may exert this activity also. In addition to the antimycobacterial activity, the hexane extract has important activity against E. histolytica and G. lamblia, and eupomatenoid-1 is one of the compounds responsible for the antiparasite activity.

Drug-Resistant tuberculosis, KwaZulu-Natal, South Africa, 2001-2007

In Africa, incidence and prevalence of drug-resistant tuberculosis have been assumed to be low. However, investigation after a 2005 outbreak of extensively drug-resistant tuberculosis in KwaZulu-Natal Province, South Africa, found that the incidence rate for multidrug-resistant tuberculosis in KwaZulu-Natal was among the highest globally and would be higher if case-finding efforts were intensified.

Antituberculosis, Antifungal and Photoluminescence Studies on a Mn(II)–Neocuproine Complex

The complex [Mn(Me2phen)(H2O)3(MeOH)][NO3]2, (Me2phen = 2,9-dimethyl-1,10-phenanthroline, neocuproine) has been prepared. Structural studies show that the [Mn (Me2phen) (H2O)3(MeOH)] cation is a six coordinate octahedral species with bidentate Me2phen and monodentate water and methanol ligands. The water molecules are hydrogen bonded to a Me2phen free ligand, which is co-crystallised in a position adjacent to the Mn complex. Face-to-face π···π stacking interactions between coordinated and free Me2phen ligand molecules generate an efficient parallel packing system in the complex, which also shows antituberculosis and antifungal activity. Photoluminescence properties are also reported.