Management of multidrug-resistant tuberculosis: Update 2007

Precision and Advanced Nano-Phytopharmaceuticals for Therapeutic Applications

Phytopharmaceuticals have been widely used globally since ancient times and acknowledged by healthcare professionals and patients for their superior therapeutic value and fewer side-effects compared to modern medicines. However, phytopharmaceuticals need a scientific and methodical approach to deliver their components and thereby improve patient compliance and treatment adherence. Dose reduction, improved bioavailability, receptor selective binding, and targeted delivery of phytopharmaceuticals can be likely achieved by molding them into specific nano-formulations. In recent decades, nanotechnology-based phytopharmaceuticals have emerged as potential therapeutic candidates for the treatment of various communicable and non-communicable diseases. Nanotechnology combined with phytopharmaceuticals broadens the therapeutic perspective and overcomes problems associated with plant medicine. The current review highlights the therapeutic application of various nano-phytopharmaceuticals in neurological, cardiovascular, pulmonary, and gastro-intestinal disorders. We conclude that nano-phytopharmaceuticals emerge as promising therapeutics for many pathological conditions with good compliance and higher acceptance.

Therapeutic effects of recombinant human interleukin 2 as adjunctive immunotherapy against tuberculosis: A systematic review and meta-analysis

Background

Interleukin 2 (IL-2) is a cytokine secreted by activated T cells. Studies exploring recombinant human interleukin 2 (rhuIL-2) as an adjunctive immunotherapeutic agent to treat tuberculosis (TB) have shown variable results; however, the true therapeutic efficacy of rhuIL-2 administration in TB patients has not been determined.

Methods

A systematic review to identify publications exploring the association between rhuIL-2-based immunotherapy for TB and outcomes (sputum culture conversion, sputum smear conversion, radiographic changes, and leukocyte phenotype changes) in patients with pulmonary TB published before June 8, 2018 was performed. Data were extracted and analyzed by two investigators independently.

Results

A total of 2,272 records were screened. Four randomized controlled trials (RCTs) comprising 656 pulmonary TB patients were finally included. The rhuIL-2 treatment could significantly improve the sputum culture conversion of TB (RR, 1.18; 95%CI: 1.03–1.36; I² < 0.01; P = 0.019) after at least 3 months of anti-TB therapy and the sputum smear conversion of TB during anti-TB therapy. Treating multidrug-resistant tuberculosis (MDR-TB) with rhuIL-2 could improve the sputum culture conversion (RR, 1.28; 95%CI: 1.05–1.57; I² < 0.01; P = 0.016) and smear conversion (RR, 1.28; 95%CI: 1.09–1.51; I² < 0.01; P = 0.003) at the end of anti-TB treatment. Meanwhile, rhuIL-2-based adjunctive immunotherapy could expand the proliferation and conversion of CD4⁺ and natural killer (NK) cells. Three of the included studies suggested that radiographic changes could not be improved by the use of rhuIL-2 as adjunctive immunotherapy. Publication bias did not exist.

Conclusions

Based on this first meta-analysis, rhuIL-2-based adjunctive immunotherapy appears to expand the proliferation and conversion of CD4⁺ and NK cells, as well as improve the sputum culture (at 3 months and later) and smear conversion of TB patients.

Patterns of Drug Resistance Among Tuberculosis Patients in West and Northwestern Iran

Background:

Tuberculosis (TB) is the leading cause of morbidity and mortality among chronic infectious diseases.

Objective:

The goal of this cross-sectional study (2011-2013;2013) was to examine the patterns of TB drug resistance among HIV-negative pulmonary TB patients in regions near the Iranian border.

Method:

To this end, MTB isolates were harvested from 300 HIV-negative, pulmonary smear-positive TB patients from the northwest and west Iranian border provinces. Isolates were subjected to first and second-line drug susceptibility testing by the 1% proportion method. Demographic and clinical data were provided using a questionnaire and information from patient records. Results were analyzed using SPSS-18.

Results:

The mean age of the patients was 52.03 years and 54.3% were male. The prevalence of resistance to any TB drug was 13.6% (38 cases). Eleven percent of the new treatment TB group (28 patients) and 40.7% of the retreatment TB group (11 patients) were resistant to all TB drugs. Twelve (4.3%) patients had multidrug-resistant tuberculosis (MDR-TB) (2.38% in the new TB treatment group and 23.1% in the retreatment group). One patient had extensively drug-resistant tuberculosis (XDR-TB). There was a statistically significant relationship between TB drug resistance and smoking (p=0.02) and a history of migration from village to city (p=0.04), also between TB drug resistance and recurrence of TB in patients that had previously received treatment (p<0.001).

Conclusion:

Knowledge of drug resistance patterns for new and previously treated cases is critical for effective control of MDR-TB in different regions of the country. The burden of MDR-TB in retreatment cases was high. Previous TB treatment was one of the most important mokers and those who had a history of rural to urban migration were at high risk for the occurrence of TB drug resistance.

The Role of Video-Assisted Thoracoscopic Therapeutic Resection for Medically Failed Pulmonary Tuberculosis

There are few reports regarding video-assisted thoracoscopic therapeutic resection for medically failed pulmonary tuberculosis (TB). We reviewed our surgical results of video-assisted thoracoscopic surgery (VATS) therapeutic resection for pulmonary TB with medical failure, and its correlation with image characteristics on chest computed tomography (CT) scan.Between January 2007 and December 2012, among the 203 patients who had surgery for TB, the medical records of 89 patients undergoing therapeutic resection for medically failed pulmonary TB were reviewed. Clinical information and the image characteristics of CT scan were investigated and analyzed.Forty-six of the 89 patients undergoing successful VATS therapeutic resection had significantly lower grading in pleural thickening (P < 0.001), peribronchial lymph node calcification (P < 0.001), tuberculoma (P = 0.015), cavity (P = 0.006), and aspergilloma (P = 0.038); they had less operative blood loss (171.0 ± 218.7 vs 542.8 ± 622.8 mL; P < 0.001) and shorter hospital stay (5.2 ± 2.2 vs 15.6 ± 15.6 days; P < 0.001). They also had a lower percentage of anatomic resection (73.9% vs 93.0%; P = 0.016), a higher percentage of sublobar resection (56.5% vs 32.6%; P = 0.023), and a lower disease relapse rate (4.3% vs 23.3%; P = 0.009). Eighteen of the 38 patients with multi-drug resistant pulmonary tuberculosis (MDRTB) who successfully underwent VATS had significantly lower grading in pleural thickening (P = 0.001), peribronchial lymph node calcification (P = 0.019), and cavity (P = 0.017). They were preoperatively medicated for a shorter period of time (221.6 ± 90.8 vs 596.1 ± 432.5 days; P = 0.001), and had more sublobar resection (44.4% vs 10%), less blood loss (165.3 ± 148.3 vs 468.0 ± 439.9 mL; P = 0.009), and shorter hospital stay (5.4 ± 2.6 vs 11.8 ± 6.9 days; P = 0.001).Without multiple cavities, peribronchial lymph node calcification, and extensive pleural thickening, VATS therapeutic resection could be safely performed in selected patients with medically failed pulmonary TB as an effective adjunct with satisfactory results.

Screening for Tuberculosis Among Adults Newly Diagnosed With HIV in Sub-Saharan Africa: A Cost-Effectiveness Analysis

OBJECTIVE

New tools, including light-emitting diode (LED) fluorescence microscopy and the molecular assay Xpert MTB/RIF, offer increased sensitivity for tuberculosis (TB) in persons with HIV but come with higher costs. Using operational data from rural Malawi, we explored the potential cost-effectiveness of on-demand screening for TB in low-income countries of Sub-Saharan Africa.

DESIGN AND METHODS

Costs were empirically collected in 4 clinics and in 1 hospital using a microcosting approach, through direct interview and observation from the national TB program perspective. Using decision analysis, newly diagnosed persons with HIV were modeled as being screened by 1 of the 3 strategies: Xpert, LED, or standard of care (ie, at the discretion of the treating physician).

RESULTS

Cost-effectiveness of TB screening among persons newly diagnosed with HIV was largely determined by 2 factors: prevalence of active TB among patients newly diagnosed with HIV and volume of testing. In facilities screening at least 50 people with a 6.5% prevalence of TB, or at least 500 people with a 2.5% TB prevalence, Xpert is likely to be cost-effective. At lower prevalence-including that observed in Malawi-LED microscopy may be the preferred strategy, whereas in settings of lower TB prevalence or small numbers of eligible patients, no screening may be reasonable (such that resources can be deployed elsewhere).

CONCLUSIONS

TB screening at the point of HIV diagnosis may be cost-effective in low-income countries of Sub-Saharan Africa, but only if a relatively large population with high prevalence of TB can be identified for screening.

Inhibition of mycobacterial alanine racemase activity and growth by thiadiazolidinones

The genus Mycobacterium includes non-pathogenic species such as M. smegmatis, and pathogenic species such as M. tuberculosis, the causative agent of tuberculosis (TB). Treatment of TB requires a lengthy regimen of several antibiotics, whose effectiveness has been compromised by the emergence of resistant strains. New antibiotics that can shorten the treatment course and those that have not been compromised by bacterial resistance are needed. In this study, we report that thiadiazolidinones, a relatively little-studied heterocyclic class, inhibit the activity of mycobacterial alanine racemase, an essential enzyme that converts l-alanine to d-alanine for peptidoglycan synthesis. Twelve members of the thiadiazolidinone family were evaluated for inhibition of M. tuberculosis and M. smegmatis alanine racemase activity and bacterial growth. Thiadiazolidinones inhibited M. tuberculosis and M. smegmatis alanine racemases to different extents with 50% inhibitory concentrations (IC50) ranging from <0.03 to 28μM and 23 to >150μM, respectively. The compounds also inhibited the growth of these bacteria, including multidrug resistant strains of M. tuberculosis. The minimal inhibitory concentrations (MIC) for drug-susceptible M. tuberculosis and M. smegmatis ranged from 6.25μg/ml to 100μg/ml, and from 1.56 to 6.25μg/ml for drug-resistant M. tuberculosis. The in vitro activities of thiadiazolidinones suggest that this family of compounds might represent starting points for medicinal chemistry efforts aimed at developing novel antimycobacterial agents.

Meropenem inhibits D,D-carboxypeptidase activity in Mycobacterium tuberculosis

Carbapenems such as meropenem are being investigated for their potential therapeutic utility against highly drug-resistant tuberculosis. These β-lactams target the transpeptidases that introduce interpeptide cross-links into bacterial peptidoglycan thereby controlling rigidity of the bacterial envelope. Treatment of Mycobacterium tuberculosis (Mtb) with the β-lactamase inhibitor clavulanate together with meropenem resulted in rapid, polar, cell lysis releasing cytoplasmic contents. In Mtb it has been previously demonstrated that 3-3 cross-linkages [involving two diaminopimelate (DAP) molecules] predominate over 4-3 cross-linkages (involving one DAP and one D-alanine) in stationary-phase cells. We purified and analysed peptidoglycan from Mtb and found that 3-3 cross-linkages predominate throughout all growth phases and the ratio of 4-3/3-3 linkages does not vary significantly under any growth condition. Meropenem treatment was accompanied by a dramatic accumulation of unlinked pentapeptide stems with no change in the tetrapeptide pools, suggesting that meropenem inhibits both a D,D-carboxypeptidase and an L,D-transpeptidase. We purified a candidate D,D-carboxypeptidase DacB2 and showed that meropenem indeed directly inhibits this enzyme by forming a stable adduct at the enzyme active site. These results suggest that the rapid lysis of meropenem-treated cells is the result of synergistically inhibiting the transpeptidases that introduce 3,3-cross-links while simultaneously limiting the pool of available substrates available for cross-linking.

Respiratory health issues in the Asia-Pacific region: an overview

The Asia–Pacific region is home to a large heterogeneous population whose respiratory health is influenced by diverse social, economic and environmental factors. Despite this variability, the most prevalent causes of respiratory morbidity and mortality are tobacco smoking, infection, and air pollution. This review aims to summarize current respiratory health issues in the region including smoking‐related diseases especially COPD, lung cancer and infectious problems such as pandemic influenza, the severe acute respiratory syndrome coronavirus, bacterial pneumonia and tuberculosis, as well as the contribution of air pollution to respiratory disease. Published data on trends in the epidemiology and management of respiratory diseases and are summarized; finally, the limitations of available data and projections for the future of respiratory health in the region are discussed.

Epidemiology of anti-tuberculosis drug resistance in a Chinese population: current situation and challenges ahead

Background

Drug resistance has been a cause of concern for tuberculosis (TB) control in both developed and developing countries. Careful monitoring of the patterns and trends of drug resistance should remain a priority.

Methods

Strains were collected from 1824 diagnosed sputum smear positive pulmonary TB patients in Jiangsu province of China and then tested for drug susceptibility against rifampicin, isoniazid, ethambutol and streptomycin. The prevalence and patterns of drug resistance in mycobacterium tuberculosis (MTB) isolates were investigated. Multiple logistic regression analysis was performed to identify the risk factors for multidrug resistant (MDR) bacterial infection. The strength of association was estimated by odds ratio (OR) and 95% confidence interval (95% CI).

Results

The drug susceptibility tests showed that 1077(59.05%) MTB strains were sensitive to all the four antibiotics and the other 747(40.95%) strains were resistant to at least one drug. The proportions of mono-drug resistance were 28.73% for isoniazid, 19.41% for rifampicin, 29.33% for streptomycin, and 13.98% for ethambutol, respectively. The prevalence of MDR-TB was 16.61%, which was significantly different between new cases (7.63%) and those with previous treatment history (33.07%). Geographical variation of drug resistance was observed, where the proportion of MDR-TB among new cases was higher in the central (9.50%) or north part (9.57%) than that in the south area (4.91%) of Jiangsu province. The age of patients was significantly associated with the risk of drug resistance (P < 0.001) and the adjusted OR (95% CI) was 1.88(1.26-2.81) for patients aged 35-44 years when compared with those 65 years or older. Patients with previous treatment history had a more than 5-fold increased risk of MDR-TB (adjusted OR: 6.14, 95% CI: 4.61-8.17), compared with those previously not having been treated.

Conclusions

The high prevalence of drug resistance has been a major challenge for TB control. Prevention and control of drug-resistant TB should be emphasized by the revised DOTS (direct observed therapy, short course) program through prompt case detection, routine and quality-assured drug susceptibility test for patients at high risk of resistance, programmatic treatment with both first and second-line medicines, and systematic treatment observation, with priority for high MDR-TB settings.

Structure of the Mycobacterium tuberculosis D-alanine:D-alanine ligase, a target of the antituberculosis drug D-cycloserine

D-alanine:D-alanine ligase (EC 6.3.2.4; Ddl) catalyzes the ATP-driven ligation of two D-alanine (D-Ala) molecules to form the D-alanyl:D-alanine dipeptide. This molecule is a key building block in peptidoglycan biosynthesis, making Ddl an attractive target for drug development. D-Cycloserine (DCS), an analog of D-Ala and a prototype Ddl inhibitor, has shown promise for the treatment of tuberculosis. Here, we report the crystal structure of Mycobacterium tuberculosis Ddl at a resolution of 2.1 Å. This structure indicates that Ddl is a dimer and consists of three discrete domains; the ligand binding cavity is at the intersection of all three domains and conjoined by several loop regions. The M. tuberculosis apo Ddl structure shows a novel conformation that has not yet been observed in Ddl enzymes from other species. The nucleotide and D-alanine binding pockets are flexible, requiring significant structural rearrangement of the bordering regions for entry and binding of both ATP and D-Ala molecules. Solution affinity and kinetic studies showed that DCS interacts with Ddl in a manner similar to that observed for D-Ala. Each ligand binds to two binding sites that have significant differences in affinity, with the first binding site exhibiting high affinity. DCS inhibits the enzyme, with a 50% inhibitory concentration (IC(50)) of 0.37 mM under standard assay conditions, implicating a preferential and weak inhibition at the second, lower-affinity binding site. Moreover, DCS binding is tighter at higher ATP concentrations. The crystal structure illustrates potential drugable sites that may result in the development of more-effective Ddl inhibitors.

Current development and future prospects in chemotherapy of tuberculosis

Although treatment of drug-susceptible tuberculosis (TB) under ideal conditions may be successful in >or=95% of cases, cure rates in the field are often significantly lower due to the logistical challenges of administering and properly supervising the intake of combination chemotherapy for 6-9 months. Success rates are far worse for multidrug-resistant and extensively drug-resistant TB cases. There is general agreement that new anti-TB drugs are needed to shorten or otherwise simplify treatment for drug-susceptible and multidrug-resistant/extensively drug-resistant-TB, including TB associated with HIV infection. For the first time in over 40 years, a nascent pipeline of new anti-TB drug candidates has been assembled. Eleven candidates from seven classes are currently being evaluated in clinical trials. They include novel chemical entities belonging to entirely new classes of antibacterials, agents approved for use against infections other than TB, and an agent already approved for limited use against TB. In this article, we review the current state of TB treatment and its limitations and provide updates on the status of new drugs in clinical trials. In the conclusion, we briefly highlight ongoing efforts to discover new compounds and recent advances in alternative drug delivery systems.

Respiratory infections: a current and future threat

Despite all the medical progress in the last 50 years pulmonary infections continue to exact and extremely high human and economic cost. This review will focus on the human, pathogen and environmental factors that contribute to the continued global burden or respiratory diseases with a particular focus on areas where we might hope to see some progress in the coming decades.

Epidemiology and treatment of multidrug resistant tuberculosis

Multidrug resistant tuberculosis is now thought to afflict between 1 and 2 million patients annually. Although significant regional variability in the distribution of disease has been recorded, surveillance data are limited by several factors. The true burden of disease is likely underestimated. Nevertheless, the estimated burden is substantial enough to warrant concerted action. A range of approaches is possible, but all appropriate interventions require scale-up of laboratories and early treatment with regimens containing a sufficient number of second-line drugs. Ambulatory treatment for most patients, and improved infection control, can facilitate scale-up with decreased risk of nosocomial transmission. Several obstacles have been considered to preclude worldwide scale-up of treatment, mostly attributable to inadequate human, drug, and financial resources. Further delays in scale-up, however, risk continued generation and transmission of resistant tuberculosis, as well as associated morbidity and mortality.