Spread Of Multidrug-resistant Tuberculosis Research Articles

Multidrug resistant tuberculosis (MDR-TB) in emerging economies in Sub-Saharan Africa: clinicians’ public health concerns

Despite improvement in the control of Tuberculosis globally, the disease remains a major public health problem responsible for high morbidity and mortality. In 2013 alone an estimated 9 million people acquired Tuberculosis, while mortality was at 1.5 million people that year. The emergence of multidrug resistant tuberculosis (MDR-TB) is tending to reverse earlier gains in the Tuberculosis control efforts, especially in resources limited settings in Sub Saharan Africa (SSA). The largest negative impact is expected in high-risk populations in whom the prevalence of pulmonary TB is already high. The challenges in these settings are numerous and are important for the epidemiology of MDR-TB. Alliances of negative forces and social determinants of health such as poverty, low levels of literacy, gender inequality and poorly resourced health systems may play a big role in the spread of MDR-TB. Furthermore, high cost of treatment and lack of health workers are hindrances to proper control of TB. HIV infection and male gender have been cited to be risk factors. Efforts to control this epidemic require control of HIV and more male involvement in the most affected regions. In our perspective we discuss epidemiology of MRD-TB in SSA.

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis.

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread of multi drug-resistant TB (MDR-TB), there is a real urgency to develop new therapeutic strategies against M. tuberculosis infections. Traditionally, compounds are evaluated based on their antibacterial activity under in vitro growth conditions in broth; however, results are often misleading for intracellular pathogens like M. tuberculosis since in-broth phenotypic screening conditions are significantly different from the actual disease conditions within the human body. Screening for inhibitors that work inside macrophages has been traditionally difficult due to the complexity, variability in infection, and slow replication rate of M. tuberculosis. In this study, we report a new approach to rapidly assess the effectiveness of compounds on the viability of M. tuberculosis in a macrophage infection model. Using a combination of a cytotoxicity assay and an in-broth M. tuberculosis viability assay, we were able to create a screening system that generates a comprehensive analysis of compounds of interest. This system is capable of producing quantitative data at a low cost that is within reach of most labs and yet is highly scalable to fit large industrial settings.

Molecular Genetic Determination of MDR–TB Isolates from West Bengal, India

Tuberculosis (TB) is one of the leading causes of death from an infectious disease worldwide. India remains to be the country carrying highest burden of the disease. One of the potent problems of present days, in this field, is the emergence of Multi-Drug-Resistant Tuberculosis (MDR-TB). MDR is defined as resistance to isoniazid (INH) and rifampin (RIF). The spread of MDR-TB is one of the biggest challenges to global public health system. Thus, detection of MDR-TB strains is critically important for containment of global TB epidemics. In this study, we are determining the MDR incidence rate in the West Bengal state of India, which is one of the most TB prone areas of the world. The RIF-resistant mutations of Mycobacterium tuberculosis (MTB) were shown to map in the rpoB locus and INH-resistant mutations of MTB were shown to map in inhA and katG loci. Therefore, in the present study, we have detected MDR-TB strains by mapping rpoB, katG & inhA mutations. Our Line Probe Assay (LPA) based results from a vast pool of MTB organisms (carrying 3653 bonafide sputum positive patient isolates) indicated the presence of 14.37% MDR isolates which matches in general with the previously reported results from various parts of the world (approx. 12-16%). Therefore, we conclude that our MDR rate is generally comparable to that of the other investigations performed in the rest of the world. We also found that the male patients are more likely to contract the MDR strains than the female patients (1.97:1.0). This data also conforms to the global statistics.

Drug susceptibility profiles of pulmonary Mycobacterium tuberculosis isolates from patients in informal urban settlements in Nairobi, Kenya.

BackgroundAnti-tuberculosis drug resistance is an emerging health problem in Kenya and especially in slums. Slum environments create a conducive environment for the spread of tuberculosis (TB) due to high population density and lack of basic amenities such as decent housing, access to clean water, lack of drainage and basic sanitation. Furthermore, ineffective health services in crowded and poorer populations, poor patient compliance, a large pool of untreated cases, delayed diagnosis and inappropriate treatment regimens are likely to favour selection and spread of drug resistant Mycobacterium tuberculosis (Mtb) strains in such settings, however, precise data on this problem are only sparsely available. To address this question, this study aimed at determining drug resistance patterns of Mtb strains obtained from pulmonary TB patients who sought health care in randomly selected informal settings.MethodsThis is a cross-sectional study conducted between September 2014 and March 2015, sputum samples were collected from 223 consenting adult patients and subjected to primary isolation and drug susceptibility testing. Socio-demographic data was collected and all data analysed using SPSS v20.ResultsDrug susceptibility testing against first line drugs was successfully carried out on 184 isolates. Resistance to at-least one drug was observed in 33 % of the isolates. The highest prevalence of resistance to any drug was identified against isoniazid,(INH) (23.9 %) followed by Ethambutol (EMB) (13.6 %). The highest proportion of mono resistance was observed against INH, 25 (13.6 %). Multidrug resistance (MDR) was observed in 4.4 % of the new cases. There was no significant difference in the proportion of any resistance by sex, age or previous treatment.ConclusionLevels of drug resistance have reached an alarming level in this population. Capacity of laboratories to conduct TB culture and DST should be strengthened in order to adequately manage TB patients and stop further creation and spread of MDR TB.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1920-5) contains supplementary material, which is available to authorized users.

Persistently high prevalence of primary resistance and multidrug resistance of tuberculosis in Heilongjiang Province, China.

BackgroundThe spread of multidrug-resistant tuberculosis (MDR-TB) Mycobacterium tuberculosis (M. tuberculosis) strains has been a big challenge to the TB control and prevention in China. Knowledge about patterns of drug resistance in TB high-burden areas of China is crucial to develop appropriate control strategies. We conducted a comprehensive investigation of the resistance pattern of M. tuberculosis in Heilongjiang Province.Methods1427 M. tuberculosis clinical strains were isolated from pulmonary TB patients hospitalized between 2007 and 2012. The susceptibility of the isolates to the first-line anti-TB drugs and the resistance of MDR M. tuberculosis to fluoroquinolones were examined. We also performed a statistical analysis to identify the correlated risk factors for high burden of MDR-TB.ResultsThe global resistance rates of 2007–2012 to the first-line drugs and MDR were 57.0 and 22.8 %, respectively. Notably, the primary MDR-TB and pan-resistance rates were as high as 13.6 and 5.0 %, respectively. Of MDR M. tuberculosis isolates (2009), approximately 13 % were not susceptible to any of the fluoroquinolones tested. Being age of 35 to 54, high re-treatment proportion, the presence of cavity lesion, and high proportion of shorter hospitalization are correlated with the development of MDR-TB.ConclusionsThe high prevalence of drug resistant, MDR-TB, and fluoroquinolone-resistant MDR-TB is a big concern for TB control. More importantly, in order to control the development of MDR-TB effectively, we need to pay more attention to the primary resistance. Targeting reducing the prevalence of the risk factors may lead to better TB control in China.

Bioinformatics Identification of Drug Resistance-Associated Gene Pairs in Mycobacterium tuberculosis

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis (Mtb). Due to the extensive use of anti-tuberculosis drugs and the development of mutations, the emergence and spread of multidrug-resistant tuberculosis is recognized as one of the most dangerous threats to global tuberculosis control. Some single mutations have been identified to be significantly linked with drug resistance. However, the prior research did not take gene-gene interactions into account, and the emergence of transmissible drug resistance is connected with multiple genetic mutations. In this study we use the bioinformatics software GBOOST (The Hong Kong University, Clear Water Bay, Kowloon, Hong Kong, China) to calculate the interactions of Single Nucleotide Polymorphism (SNP) pairs and identify gene pairs associated with drug resistance. A large part of the non-synonymous mutations in the drug target genes that were included in the screened gene pairs were confirmed by previous reports, which lent sound solid credits to the effectiveness of our method. Notably, most of the identified gene pairs containing drug targets also comprise Pro-Pro-Glu (PPE) family proteins, suggesting that PPE family proteins play important roles in the drug resistance of Mtb. Therefore, this study provides deeper insights into the mechanisms underlying anti-tuberculosis drug resistance, and the present method is useful for exploring the drug resistance mechanisms for other microorganisms.

Parallel reaction monitoring of clinical Mycobacterium tuberculosis lineages reveals pre-existent markers of rifampicin tolerance in the emerging Beijing lineage

The spread of multidrug resistant Mycobacterium tuberculosis is one of the major challenges in tuberculosis control. In Eurasia, the spread of multidrug resistant tuberculosis is driven by the M. tuberculosis Beijing genotype. In this study, we examined whether selective advantages are present in the proteome of Beijing isolates that contribute to the emergence of this genotype. To this end, we compared the proteome of M. tuberculosis Beijing to that of M. tuberculosis H37Rv, both in the presence and absence of the first-line antibiotic rifampicin. During rifampicin exposure, both M. tuberculosis genotypes express proteins belonging to the DosR dormancy regulon, which induces a metabolically hypoactive-, drug tolerant phenotype. However, these markers of rifampicin tolerance were already more abundant in the M. tuberculosis Beijing isolate prior to drug exposure. To determine whether the a priori high abundance of specific proteins contribute to the formation of antibiotic resistance in M. tuberculosis Beijing, we quantified the abundance of 33 selected proteins in 27 clinical isolates from the five most common M. tuberculosis lineages using parallel reaction monitoring. The observed pre-existing high abundance of dormancy proteins in Beijing strains provides an evolutionary advantage that allows these strains to persist for prolonged periods during rifampicin treatment. SignificanceM. tuberculosis is the leading cause of death by a bacterial infection worldwide. Treatment-regimen to eradicate this pathogen make use of the first-line antibiotic rifampicin, which is considered to be the cornerstone of modern day anti-tuberculosis treatment. Despite the potency of rifampicin, there is an increasing occurrence of rifampicin resistant mutants in a specific cluster of M. tuberculosis, the Beijing genotype. Using both a data dependent acquisition and a targeted proteomic approach we identified markers of rifampicin tolerance to be high abundant in members of the M. tuberculosis Beijing genotype, already prior drug exposure. The identification of this M. tuberculosis Beijing specific trait will contribute to improved diagnostics and treatment of M. tuberculosis.

A study on prevalence of multi drug resistance tuberculosis and factors influencing it in Davangere district, Karnataka, India

Background: India is one of the high tuberculosis (TB) burden countries in the world accounting for nearly 20% of the global incidence. Standard anti-TB drugs have been used for decades, and resistance to the medicines is growing. The emergence and spread of multi-drug resistant tuberculosis (MDR-TB) is threatening to destabilize global tuberculosis control. Methods: Case records of all the patients put on DOTS plus therapy for MDR-TB were obtained from District Tuberculosis Centre (DTC) located at Chigateri General Hospital Davangere. Details of all the suspected MDR-TB patients registered in the DTC during January 2013 to June 2015 and sent for culture and drug sensitivity testing (DST) were obtained. MDR-TB was defined as Tuberculosis caused by bacilli showing resistant to Isoniazid and Rifampicin. Cases are analysed based on MDR Suspect criteria as per RNTCP. Further details about the influencing factors were obtained by calling the patients on their contact numbers. Corroborative evidence of the details provided by the patients regarding the influencing factors was substantiated from STLS or DOTS providers. Results: The prevalence of MDR-TB cases in three years was 32/4136 cases. Among the factors age, gender, pattern of resistant and high Random Blood Sugar level were the key determining factors influencing MDR-TB. Conclusions: A main component in stopping the spread of MDR-TB is to rapidly diagnose infectious TB disease cases and treat these so the patient can be cured and the chain of transmission will be stopped.

Use of Cost Effective Semi-Automated (Mannual/Micro) MGIT System over BACTEC 960 to Perform First Line Anti-Tuberculosis Drugs Sensitivity Testing

Introduction: Multi-drug resistant tuberculosis (MDR-TB) that is the tuberculosis that is resistant to at least 2 of the first line anti-tuberculosis drugs is fatal infectious disease. Cases of MDR-TB are now increasing with 30,000 cases of MDR-TB reported in 2013 by national TB programme. Rapid diagnosis of MDR-TB is extremely important for rapid treatment of patient and to prevent spread of MDR-TB to other. BACTEC 960 system helps in rapid diagnosis but purchase of expensive instrument for the same is the limitation. However, the same purpose can be solved by use of semi-automated MGIT system. Aims and Objectives: Aim of this study is to do drug sensitivity testing of the first line anti-tuberculosis drugs with the use of semi-automated MGIT systems. 350 newly registered and suspected cases of tuberculosis in tertiary care hospital were included. Samples were processed for digestion and decontamination and inoculated in MGIT tubes and also on LJ medium. Reading was taken using semi-automated MGIT system. Positive tubes were confirmed by rapid test for M. tuberculosis and then drug sensitivity was performed. Result: Out of 350 samples, 62% were sputum; 33% were pleural fluid and rest 5% were lymph node, Ascetic fluid, CSF, pus. Average day of positivity by MGIT was 13 - 20 days as compared to 25 - 37 days by solid medium, which was statistically significant with p value < 0.01. MDR cases were 2% out of 350 samples. Conclusion: Manual MGIT System is a simple, efficient, safe to use diagnostic system. It does not require any expensive/special instrumentation other than the UV lamp for detection of fluorescence. The rapidity by which mycobacteria are detected is the most important advantage of the Manual MGIT. In areas with limited resources where purchase of expensive instruments such as the MGIT960 is out of scope, the use of manual MGIT for rapid susceptibility testing for MDR-TB could be a possibility.

Risk Factors for Multidrug-Resistant Tuberculosis among Patients with Pulmonary Tuberculosis at the Central Chest Institute of Thailand.

There are limited data available on the risk factors for multidrug-resistant tuberculosis (MDR-TB). Therefore, we here conducted a retrospective matched case−control study among adults with pulmonary TB who received treatment at the Central Chest Institute of Thailand (CCIT) between January 2007 and December 2013, in order to determine the risk factors associated with MDR-TB among patients with pulmonary TB. We identified 145 patients with pulmonary MDR-TB (cases) and 145 patients with drug-sensitive pulmonary TB (controls). Multivariate analysis identified the independent risk factors for MDR-TB as follows: (1) ≥ 2 episodes of prior pulmonary TB (odds ratio [OR] 39.72, 95% confidence interval (95% CI) 7.86−200.66), (2) duration of illness > 60 days (OR 3.08, 95% CI 1.52−6.22), (3) sputum acid fast bacilli smear 3+ (OR 13.09, 95% CI 4.64−36.91), (4) presence of lung cavities (OR 3.82, 95% CI 1.89−7.73), and (5) presence of pleural effusion (OR 2.75, 95% CI 1.06−7.16). Prior pulmonary TB management with a non-category I regimen (P = 0.012) and having treatment failure or default as treatment outcomes (P = 0.036) were observed in a higher proportion among patients with MDR-TB. Particular characteristics of lung cavities, including the maximum diameter ≥ 30 mm (P < 0.001), the number of cavities ≥ 3 (P = 0.001), bilateral involvement (P < 0.001), and ≥ 2 lung zones involved (P = 0.001) were more commonly observed in patients with MDR-TB. In conclusion, these clinical factors and chest radiographic findings associated with MDR-TB among patients with pulmonary TB may help physicians to provide proper management of cases for prevention of the development and spread of MDR-TB in future.

Prevalence and drug resistance profile of Mycobacterium tuberculosis isolated from pulmonary tuberculosis patients attending two public hospitals in East Gojjam zone, northwest Ethiopia.

BackgroundThe spread of multidrug-resistant tuberculosis (MDR-TB) strains has become a challenge to the global TB control and prevention program. In Ethiopia, particularly in rural areas, information on drug-resistant TB is very limited. In this study, we determined the drug resistance patterns of Mycobacterium tuberculosis (M. tuberculosis) isolates from pulmonary TB patients attending two public hospitals in the East Gojjam zone of northwest Ethiopia.MethodsA cross-sectional study was conducted between May 2011 and January 2012 using Region of difference-9 (RD9) typing for the identification of species mycobacterium. Drug susceptibility testing (DST) of M. tuberculosis isolates to the first-line drugs: isoniazid, rifampicin, ethambutol and streptomycin was performed by the indirect proportion method on Middle brook 7H10 Agar media.ResultsOut of 385 pulmonary TB suspects studied, 124 (32.2 %) were culture positive among which 120 were M. tuberculosis strains. Susceptibility testing was performed for 89 isolates. Resistance to at least one drug was 15.58 % ([12/77], 95 % CI: 7.48-23.68) among newly diagnosed and 50.0 % ([6/12], 95 % CI: 21.71-78.29) among previously treated cases. Resistance among newly diagnosed patients was most common for streptomycin 5.19 % (4/77) and ethambutol 5.19 % (4/77) followed by rifampicin 3.89 % (3/77). Among retreatment cases, isoniazid resistance was most frequent in which 33.33 % (4/12) of the isolates were resistant. MDR prevalence was 1.29 % (1/77) for newly diagnosed and 16.67 % (2/12) for retreatment cases. In a multivariate logistic regression analysis, age group of 25–34 years (adjusted OR = 4.24; 95 % CI: 1.02-17.5; P = 0.046) and previous history of treatment (adjusted OR = 5.42; 95 % CI: 1.56-27.49; P = 0.01) were independently associated with anti-TB drug resistance.ConclusionsIn general, the magnitude of anti-TB drug resistance including MDR-TB was comparable to previous studies in other areas of Ethiopia. However, rifampicin resistance was high, which could suggest the potential for a rise in the incidence of MDR. Therefore, re-enforcing TB control programs should be considered by the concerned public health authorities.

Outbreak of multidrug-resistant tuberculosis in an aboriginal family in eastern Taiwan

Spread of multidrug-resistant tuberculosis (MDR-TB) strains in the general population presents a serious threat to public health and severely threatens existing control efforts. Techniques such as spoligotyping and Mycobacterium interspersed repetitive units—variable-number tandem-repeat typing of mycobacterial isolates have been employed to confirm familial outbreaks of MDR-TB. We diagnosed and traced four MDR-TB cases in a family via genotyping. Despite aggressive treatment, the index case remained culture positive, but the other patients were cured. This is the first documentation of a familial MDR-TB outbreak affecting human immunodeficiency virus-seronegative patients in eastern Taiwan. Molecular techniques are important in the identification of sources of MDR-TB infections. The adult index case in our study developed MDR-TB due to poor compliance with the drug regimen (acquired resistance), followed by transmission of MDR-TB to his children in close household contact. This emphasizes the importance of an effective drug delivery program, such as directly observed treatment, to improve drug compliance and prevent the emergence of drug-resistant cases.

Update on the epidemiology of tuberculosis in Italy.

As in many countries in Western Europe, in Italy tuberculosis (TB) is a relatively rare disease. In the last decade its incidence has remained constant at under 10 cases/100,000 inhabitants, the threshold considered to define a country as low prevalence. The epidemiological picture, however, is very different in the countries of Eastern Europe and in Africa, Asia, and Latin America, where the incidence of TB continues to increase and in some cases is accompanied by the emergence and spread of multidrug-resistant TB. The present review describes the epidemiology of TB in Italy. In 2008, the incidence rate was 3.8 cases per 100,000 for people born in Italy, and 50-60 cases per 100,000 for those born abroad. There was an increase in cases from Eastern Europe. The crude mortality rate for TB in 2006 was 0.7 deaths per 100,000 residents. Although TB is a low-prevalence disease in Italy, its epidemiology is changing. Since 1955, more than 160,000 people in Italy have died from this potentially preventable and curable disease.

Facing multi-drug resistant tuberculosis

Multi-drug resistant tuberculosis (MDR-TB) is caused by Mycobacterium tuberculosis strains resistant to at least two of the most effective anti-tuberculosis drugs (i.e., isoniazid and rifampicin). Therapeutic regimens based on second- and third-line anti-tuberculosis medicines showed poor efficacy, safety, and tolerability profiles. It was estimated that in 2012 the multi-drug resistant tuberculosis incidence ranged from 300,000 to 600,000 cases, mainly diagnosed in the Eastern European and Central Asian countries. The highest proportion of cases is among individuals previously exposed to anti-tuberculosis drugs. Three main conditions can favour the emergence and spread of multi-drug resistant tuberculosis: the poor implementation of the DOTS strategy, the shortage or the poor quality of the anti-tuberculosis drugs, and the poor therapeutic adherence of the patients to the prescribed regimens.Consultation with tuberculosis experts (e.g., consilium) is crucial to tailor the best anti-tuberculosis therapy.New therapeutic options are necessary: bedaquiline and delamanid seem promising drugs; in particular, during the development phase they demonstrated a protective effect against the emergence of further resistances towards the backbone drugs. In the recent past, other antibiotics have been administered off-label: the most relevant efficacy, safety, and tolerability profile was proved in linezolid-, meropenem/clavulanate-, cotrimoxazole-containing regimens.New research and development activities are needed in the diagnostic, therapeutic, preventive fields.

Classical against molecular-genetic methods for susceptibility testing of antituberculotics.

Tuberculosis currently belongs to rare respiratory diseases in Slovakia. However, the emergence and spread of multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are major challenges for global tuberculosis control, since the treatment of resistant forms creates both medical and financial problems. Cultivation methods of diagnosis are time-consuming, many times exceeding the time of the initial phase of tuberculosis treatment. Therefore, in the presented study we compared the standard procedures, based on the cultivation of mycobacteria and subsequent drug susceptibility testing to antituberculotics, with molecular-genetic methods using PCR diagnostic kits. The molecular-genetic testing enables to obtain direct and fast evidence of Mycobacterium tuberculosis, with genomic verification of resistance to the most important anti-tuberculosis drugs - isoniazid and rifampicin in MDR-TB, and ethambutol, aminoglycosides, and fluoroquinolones in XDR-TB. In 2012-2013, we confirmed 19 cases of drug-resistant tuberculosis in Slovakia. The resistance to rifampicin was confirmed in all strains with both methods. In two cases, the molecular-genetic testing did not show resistance to isoniazid, as confirmed by conventional cultivation. Furthermore, two strains demonstrating susceptibility in conventional microbiological testing to ethambutol and five strains to fluoroquinolones were verified as actually being resistant using a PCR method. Rapid diagnosis and identification of MDR-TB or XDR-TB strains using molecular-genetic testing is an essential tool for the timely and appropriate drug treatment and prevention of spread of drug resistant strains.

Use of GenoType® MTBDRplus assay to assess drug resistance and mutation patterns of multidrug-resistant tuberculosis isolates in northern India

Purpose: The emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is a major public health problem. The diagnosis of MDR-TB is of paramount importance in establishing appropriate clinical management and infection control measures. The aim of this study was to evaluate drug resistance and mutational patterns in clinical isolates MDR-TB by GenoType® MTBDRplus assay. Material and Methods: A total of 350 non-repeated sputum specimens were collected from highly suspected drug-resistant pulmonary tuberculosis (PTB) cases; which were processed by microscopy, culture, differentiation and first line drug susceptibility testing (DST) using BacT/ALERT 3D system. Results: Among a total of 125 mycobacterium tuberculosis complex (MTBC) strains, readable results were obtained from 120 (96%) strains by GenoType® MTBDRplus assay. Only 45 MDR-TB isolates were analysed for the performance, frequency and mutational patterns by GenoType® MTBDRplus assay. The sensitivity of the GenoType® MDRTBplus assay for detecting individual resistance to rifampicin (RIF), isoniazid (INH) and multidrug resistance was found to be 95.8%, 96.3% and 97.7%, respectively. Mutation in codon S531L of the rpoB gene and codon S315T1 of katG genes were dominated in MDR-TB strains, respectively (P < 0.05). Conclusions: The GenoType® MTBDRplus assay is highly sensitive with short turnaround times and a rapid test for the detection of the most common mutations conferring resistance in MDR-TB strains that can readily be included in a routine laboratory workflow.

Detection of second-line drug resistance in Mycobacterium tuberculosis using oligonucleotide microarrays

BackgroundThe steady rise in the spread of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) requires rapid and reliable methods to identify resistant strains. The current molecular methods to detect MTB resistance to second-line drugs either do not cover an extended spectrum of mutations to be identified or are not easily implemented in clinical laboratories. A rapid molecular technique for the detection of resistance to second-line drugs in M. tuberculosis has been developed using hybridisation analysis on microarrays.MethodsThe method allows the identification of mutations within the gyrA and gyrB genes responsible for fluoroquinolones resistance and mutations within the rrs gene and the eis promoter region associated with the resistance to injectable aminoglycosides and a cyclic peptide, capreomycin. The method was tested on 65 M. tuberculosis clinical isolates with different resistance spectra that were characterised by their resistance to ofloxacin, levofloxacin, moxifloxacin, kanamycin and capreomycin. Also, a total of 61 clinical specimens of various origin (e.g., sputum, bronchioalveolar lavage) were tested.ResultsThe sensitivity and specificity of the method in the detection of resistance to fluoroquinolones were 98% and 100%, respectively, 97% and 94% for kanamycin, and 100% and 94% for capreomycin. The analytical sensitivity of the method was approximately 300 genome copies per assay. The diagnostic sensitivity of the assay ranging from 67% to 100%, depending on the smear grade, and the method is preferable for analysis of smear-positive specimens.ConclusionsThe combined use of the developed microarray test and the previously described microarray-based test for the detection of rifampin and isoniazid resistance allows the simultaneous identification of the causative agents of MDR and XDR and the detection of their resistance profiles in a single day.

Diagnosis and Treatment of Multidrug-Resistant Tuberculosis in Developed and Developing Countries: Finally Towards Equality?

Tuberculosis TB is considered a sobering example of inequity. It is a disease predominantly of the socially and economically disadvantaged. This neglect is evidenced by lack of political support, scarce financial resources for TB programs, and little or no leadership. The emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is threatening global TB control and it represents a major challenge for clinical care and operational management. Worldwide, 3.7% of new cases and 20% of previously treated cases are estimated to have MDR-TB. Unfortunately, since only a quarter of patients with MDR-TB are treated according to established standards and the proportion of treatment success does not exceed 50%, extensively drugresistant tuberculosis (XDR-TB) has already been reported in 84 countries and totally drug resistant cases have been recently described. In most low- and middle-income countries drug sensitivity testing is not performed for new cases or for most patients requiring retreatment. Therefore, patients with underlying drug resistance will receive retreatment with first line drugs and can be predicted to have higher rates of failure and relapse. The development of genotypic methods has generated a genuine revolution in the diagnosis of DR-TB. The polymerase chain reaction allows for the specific identification of M. tuberculosis and the detection of drug resistance in a matter of hours instead of weeks. Unfortunately these techniques are expensive and not available in most high burden countries. Despite the enormous number of cases of TB worldwide, the therapeutic arsenal to treat this disease continues to be very limited, especially for cases with extensive drug resistance. However, for the first time in decades, the pipeline of new anti-TB agents is now growing again inasmuch as new drugs and combination of drugs with interesting potential efficacy to treat TB, MDR-TB and XDR-TB have appeared during the last few years.

Fully Integrated Thermoplastic Genosensor for the Highly Sensitive Detection and Identification of Multi‐Drug‐Resistant Tuberculosis

Infectious diseases are a major global health burden accounting for approximately 15 million deaths annually, many from drug resistant pathogenic agents, with a significant number of cases occurring in developing countries.[1–7] In particular, the resurgence of tuberculosis (TB) has been accompanied by the rapid spread of multi-drug resistance TB (MDR-TB) resulting from Mycobacterium tuberculosis (Mtb) strains that fail to respond to the first-line drugs, rifampin and isoniazid. Currently, <5% of ~0.5 million MDR-TB cases estimated globally are appropriately diagnosed and treated due in part to the long assay turnaround time associated with conventional culture-based drug susceptibility testing.[8]

Pharmacokinetics of sequential doses of capreomycin powder for inhalation in guinea pigs.

The global control of tuberculosis (TB) is at risk by the spread of multidrug-resistant TB (MDR TB). Treatment of MDR TB is lengthy and involves injected drugs, such as capreomycin, that have severe side effects. It was previously reported that a single daily dose of inhaled capreomycin had a positive effect on the bacterial burden of TB-infected guinea pigs. The modest effect observed was possibly due to a dose that resulted in insufficient time of exposure to therapeutic systemic and local levels of the drug. In order to determine the length of time that systemic and local drug concentrations are above therapeutic levels during the treatment period, the present study investigated the disposition of capreomycin powders after sequential pulmonary administration of doses of 20 mg/kg of body weight. Capreomycin concentrations in bronchoalveolar lavage fluid and lung tissue of animals receiving a series of one, two, or three doses of capreomycin inhalable powder were significantly higher (50- to 100-fold) at all time points than plasma concentrations at the same time points or those observed in animals receiving capreomycin solution by intramuscular (i.m.) injection (10- to 100-fold higher). Notably, at the end of each dosing period, capreomycin concentrations in the lungs were approximately 100-fold higher than those in plasma and severalfold higher than the MIC, suggesting that sufficient capreomycin remains in the lung environment to kill Mycobacterium tuberculosis. No accumulation of capreomycin powder was detected in the lungs after 3 pulmonary doses. These results indicate that the systemic disposition of capreomycin after inhalation is the same as when injected i.m. with the advantage that higher drug concentrations are present at all times in the lungs, the primary site of infection.