Inferring Mycobacterium Tuberculosis Drug Resistance and Transmission using Whole-genome Sequencing in a High TB-burden Setting in China

Objective China is among the 30 countries with a high burden of tuberculosis(TB)worldwide,and TB remains a public health concern.Kashgar Prefecture in the southern Xinjiang Autonomous Region is considered as one of the highest TB burden regions in China.However,molecular epidemiological studies of Kashgar are lacking.Methods A population-based retrospective study was conducted using whole-genome sequencing(WGS)to determine the characteristics of drug resistance and the transmission patterns.Results A total of 1,668 isolates collected in 2020 were classified into lineages 2(46.0%),3(27.5%),and 4(26.5%).The drug resistance rates revealed by WGS showed that the top three drugs in terms of the resistance rate were isoniazid(7.4%,124/1,668),streptomycin(6.0%,100/1,668),and rifampicin(3.3%,55/1,668).The rate of rifampicin resistance was 1.8%(23/1,290)in the new cases and 9.4%(32/340)in the previously treated cases.Known resistance mutations were detected more frequently in lineage 2 strains than in lineage 3 or 4 strains,respectively:18.6%vs.8.7 or 9%,P<0.001.The estimated proportion of recent transmissions was 25.9%(432/1,668).Multivariate logistic analyses indicated that sex,age,occupation,lineage,and drug resistance were the risk factors for recent transmission.Despite the low rate of drug resistance,drug-resistant strains had a higher risk of recent transmission than the susceptible strains(adjusted odds ratio,1.414;95%CI,1.023–1.954;P=0.036).Among all patients with drug-resistant tuberculosis(DR-TB),78.4%(171/218)were attributed to the transmission of DR-TB strains.Conclusion Our results suggest that drug-resistant strains are more transmissible than susceptible strains and that transmission is the major driving force of the current DR-TB epidemic in Kashgar.

Research progress on the drug action and resistance mechanism in Mycobacterium tuberculosis

Tuberculosis(TB)is a chronic infectious disease caused by Mycobacterium Tuberculosis(MTB).It is the second largest single cause of death besides novel coronavirus pneumonia.Along with the abuse of antibiotics and extensive use of anti-tuberculosis drugs,multidrug-resistant(MDR)TB,drug-resistant(XDR)TB and totally drug-resistant(TDR)TB became obstacles to the tuberculosis eradication worldwide.According to the World Health Organization(WHO)statistics,China is not only a high burden tuberculosis country in the world,but also a country with a serious epidemic of MDR.Traditional drugs fail to meet the needs of tuberculosis control.Therefore,it is urgent to find new targets of anti-tuberculosis drugs and develop new anti-tuberculosis drugs.Hence,this paper systematically summarizes the mechanism of traditional and newly developed anti-tuberculosis drugs,in which stressing the research progress of drug resistance mechanisms.This work provides us with new insights of new anti-tuberculosis drug developments,and may contribute to a reduction in the harm that tuberculosis brings to society.

Mutation Characteristics of inhA and katG Genes in Isoniazid-Resistant Mycobacterium Tuberculosis Patients in Xinjiang

Objective:To analyze the mutation characteristics of inhA and katG genes in isoniazid-resistant Mycobacterium tuberculosis in Xinjiang.Methods:The katG and inhA in 148 strains of isoniazid-resistant Mycobacterium tuberculosis were amplified through fluorescence quantitative PCR,and the amplified products were sequenced and compared.Results:The inhA gene mutation rate of 148 strains of isoniazid-resistant mycobacterium tuberculosis was 13.51%(20/148),among which the inhA gene mutation rate among patients of Han,Uygur,and Kazakh ethnicity were 15.87%,13.21%,and 17.65%,respectively.There was no significant difference in the inhA mutation rate among nationalities(c^(2)=2.897,P>0.05).The mutation rate of the katG gene was 84.46%(125/148),among which the mutation rates of patients of Han,Uyghur,and Kazak ethnicities were 82.54%,84.91%,and 76.47%,respectively.The Hui and other ethnic groups were all affected by the katG gene mutation.There was no significant difference in the mutation rate of the katG gene among different ethnicities(c^(2)=3.772,P>0.05).The mutation rates of the inhA gene in southern Xinjiang,northern Xinjiang,and other provinces were 18.60%,9.28%,and 37.50%,respectively.The mutation rates of the inhA gene in different regions were statistically different(c^(2)=6.381,P<0.05).There was no significant difference in the inhA mutation rate between patients from southern and northern Xinjiang(c^(2)=2.214,P>0.05)and between southern Xinjiang and other provinces(c^(2)=1.424,P>0.05).However,the mutation rate of the inhA gene in patients from other provinces was higher than that in northern Xinjiang(c^(2)=5.539,P<0.05).The mutation rates of the katG gene in southern Xinjiang,northern Xinjiang,and other provinces were 81.40%,87.63%,and 62.50%,respectively.There was no significant difference in the mutation rates of the katG gene among different regions(c^(2)=3.989,P>0.05).Conclusion:katG gene mutation was predominant in isoniazid-resistant tuberculosis patients in Xinjiang Uygur Autonomous Region,and inhA and katG gene mutation were no different among different ethnic groups.

Luciferase reporter phage phAE85 for rapid detection of rifampicin resistance in clinical isolates of Mycobacterium tuberculosis

Objective:To evaluate luciferase reporter phage(LRP)phAE85 in rapid detection of rifampicin resistance in a region where TB is endemic.Methods:One hundred and ninety primary isolates on Lowenstein-Jensen medium were tested.Middlebrook 7H9 complete medium with and without rifampicin at 2μg/mL was inoculated with standard inoculum from suspensions of the clinical isolate.After incubation for 72 h,LRP was added.Following 4 h of further incubation,light output from both control and test was measured as relative light units.Strains exhibiting a reduction of less than 50%relative light units in the drug containing vial compared to control were classified as resistant.Results were compared with the conventional minimum inhibitory concentration method(MIC)of drug susceptibility testing.Results:The two methods showed high level of agreement of 97%(CI 0.94,0.99)and P value was 0.000 1.The sensitivity and specificity of LRP assay for detection of rifampicin resistance were 91%h(CI 0.75,0.98)and 99ct(CI0.95,1.00)respectively.Time to detection of resistance by LRP assay was 3 d in comparison with 28 d by the minimum inhibitory concentration method.Conclusions:LRP assay with phAE85 is 99%specific,91%sensitive and is highly reproducible.Thus the assay offers a simple procedure for drug sensitivity testing,within die scope of semi-automation.

Drug resistance pattern of Mycobacterium tuberculosis isolates from patients of five provinces of Iran

Objective:To determine the patterns of resistance to first line anti-tuberculosis(TB)drugs among a collection of Mycobacterium tuberculosis(MTB)isolates from 5 provinces of Iran.Methods:A total of the 6 426 clinical specimens from patients suspected of active TB were collected from March 2010 to June 2012.All specimens were subjected for microscopy and culture tests in the TB centers of studies provinces.Drug susceptibility testing to the first line anti-TB drugs for culture positive MTB was performed on Lwenstein-Jensen(LJ)medium using proportion method.Results:Of 6 426 clinical specimens,261 were culture positive for mycobacteria,of which 252 were MTB and 9 were MOTT(mycobacteria other than tuberculosis).Of 252 MTB isolates.211(83.7%)were pan-susceptible and 41(16.3%)were resistant to at least one drug.Resistance was most common to streptomycin.30 isolates(12.0%),followed by isoniuzid,20isolates(8.0%),rifampin,15 isolates(6.0%)and ethambutol,14 isolates(5.5%).Sixteen(6.3%)MTB isolates were MDR.A clear evidence of heterogeneity amongst the 5 provinces in the proportions with resistance to one or more drugs was observed[χ~2=12.209(4 degrees of freedom),P values=0.015 9].Conclusions:The prevalence of drug resistance in this study area underscoring the need for further enforcement of TB control strategies in the Iran.Drug susceptibility testing for all TB cases to provide optimal treatment,establishing advanced diagnostic facilities for rapid detection of MDR-TB and continuous monitoring of drug resistance are recommended for prevention and control of drug-resistant TB.

Molecular Characterization of Drug-Resistant Beijing Family Isolates of Mycobacterium Tuberculosis from Tianjin,China

Objective Tuberculosis remains a severe public health issue, and the Beijing family of mycobacterium tuberculosis （M. tuberculosis） is widespread in East Asia, especially in some areas in China, like Beijing and Tianjin. This study aimed at determining the mutation patterns of drug-resistant Beijing strains of M. tuberculosis isolated from Tianjin, China. Methods A total of 822 M. tuberculosis isolates were screened for drug resistance by an absolute concentration method and the genotype was identified by PCR. 169 drug-resistant isolates of the Beijing family were analyzed for the potential mutations in the rpoB, katG, inhA promoter region and in rpsL, rrs and embB genes, which are associated with resistance to rifampin （RFP）, isoniazid （INH）, streptomycin （SM） and ethambutol （EMB） respectively by PCR and DNA sequencing. Results Fifty-eight out of 63 RFP-resistant isolates were found to carry the mutations within the 81-bp RFP resistance determining region （RRDR） of the rpoB gene and the most frequent mutations occurred at codon 531 （44.4%）, 526 （28.6%）, and 516 （7.9%） respectively. 16 mutation pattems affecting 12 different codons around the RRDR of rpoB were found. Of 116 INH-resistant isolates, 56 （48.3%） had the mutation of katG 315 （AGC→ACC） （Ser→Thr）, 3 （2.6%） carried S315N （AGC→AAC） and 27 （16.0%） had the mutation of inhA-15A→T. 84 out of 122 SM-resistant isolates （68.9%） displayed mutations at the codons 43 or 88 with AAG→AGG （Lys→Arg） of the rpsL gene and 22 （18.0%） with the mutations at positions 513A→C, 516C→T or 905 A→G in the rrs gene. Of 34 EMB-resistant isolates, 6 had mutation with M306V （ATG→GTG）, 3 with M306I （ATG→ATT）, 1 with M306I （ATG→ATA）, 1 with D328Y （GAT→TAT）, 1 with V348L （GTC→CTC）, and 1 with G406S （GGC→AGC） in the embB gene. Conelusion These novel findings extended our understanding of resistance-related mutations in the Beijing strains of M. tuberculosis and may provide a scientific basis for development of new strategies for diagnosis and control of tuberculosis in China and other countries where Beijing strains are prevalent.

Natural Remedies against Multi-Drug Resistant <i>Mycobacterium tuberculosis</i>

Tuberculosis (TB), caused by Mycobacterium tuberculosis is an infectious deadly disease and the treatment of which is one of the most severe challenges at the global level. Currently more than 20 chemical medications are described for the treatment of TB. Regardless of availability of several drugs to treat TB, the causative agent, M. tuberculosis is nowadays getting resistant toward the conventional drugs and leading to conditions known as Multidrug-resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis (XDR-TB). This situation has terrified the global health community and raised a demand for new anti-tuberculosis drugs. Medicinal plants have been used to cure different common as well as lethal diseases by ancient civilizations due to its virtue of variety of chemical compounds which may have some important remedial properties. The aim of the present review is to focus the anti-tubercular medicinal plants native to India as well as the plants effective against MDR or XDR-TB across the globe. In the present review, we have addressed 25 medicinal plants for TB and 16 plants effective against MDR-TB testified from India and 23 herbal plants described for MDR-TB across the world during 2011-2015. These herbal plants can serve as promising candidates for developing novel medications to combat multidrug resistant M. tuberculosis.

Detecting katG Drug Resistant Genetic Mutation among pneumoconiosis patients complicated with tuberculosis in Mycobacterium tuberculosis L-forms by PCR-SSCP

Objective：To study the relationship between mutation in the katG gene and drug resistance of INH in Mycobacterium tuberculosis L-forms among patients of pneumoconiosis complicated with pulmonary tuberculosis, and to explore the clinical application of PCR-SSCP. Methods： A total of 52 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected. Mutation in the katG genes was detected by PCR-SSCP and traditional antimicrobial susceptibility test （AST）. Results： The results by AST showed that there were 40 persisters in 52 clinical isolated strains. The drug resistant rate was 76.92%（40/52）, and the gene mutation rate of katG was 57.70%（30/52）by PCR-SSCP, the difference was no quite significance （X^2 = 2.8507, P 〉 0.05）. The coincidence rate of two methods was 75.00% （30/40）. Conclusion： The detectionrate of katG resistant strains in Mycobacterium tuberculosis L-forms was high by PCR-SSCP. The combined application of PCR-SSCP and traditional antimicrobial susceptibility test can improve the detecting rate.

A Simple LDT-PCR Method for Detection of Various Nucleic Acid Sequence Changes in a Small Region of Genes—Application for the Identification of Gene Mutations in MTB <i>rpoB</i>Gene Associated with Drug Resistance

A modified low denaturing temperature PCR (LDT-PCR) method combined with DNA microarray technique is developed in our lab for quick and effective identification of various mutations in an 81 base pair region of Mycobacterium Tuberculosis (MTB) ribosome RNA polymerase subunit B (rpoB) gene associated with rifampin resistance. By incurporation of wild type (wt) allele fragments that had been PCR amplified previously, the target PCR fragments coming from mutant clinical MTB samples were codenaturized with incorporated wt type allele fragment at 94°C and then let them randomly form matched structures (homoduplex) and allele mismatch-containing structures (heteroduplex), respectively, when the temperature cooled down to 70°C. After the temperature was raised to 80°C, the heteroduplex double stranded fragments were preferentially denatured and resulted in PCR amplification as well as fluorescence incurporation. Since the homoduplex fragments need a higher temperature to be denatured, they were kept in double-stranded status at that temperature and failed to be PCR amplified. By hybridization of LDT-PCR products with the probes spotted on microarray slides, the fluorescent signals representing the presence of gene mutations were detected. We have tested this method on 35 clinical MTB samples and obtained satisfied results.

Sequence analysis on drug-resistant rpoB gene of Mycobacterium tuberculosis L-form of isolated from pneumoconiosis workers

Objective:To study the characteristics of drug-resistant genetic mutation of rpoB on coal workers' pneumoconiosis complicated with L-form of Mycobacterium tuberculosis. Methods: A total of 42 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected, including 31 drug-resistant strains. Their genomes DNA were extracted, the target genes were amplified by PCR, and the hot regions in the rpoB gene were analyzed by automated DNA sequenator. Results: No mutation of rpoB gene was identified in 11 rifampicin-sensitive strains while conformation changes were found in 31 rifampicin-resistant strains. The mutation rate was 93.55% (29/31) in resistant strains, mainly concentrated in codon 531 (51.6%, 16/31) and 526 (32.26%, 10/31). Base substitutions happened, including 27 unit point mutation and 2 two point mutation. The mutation of codon 516 that new found wasn't reported by internal and overseas scholars. Conclusion: The substitution of highly conserved amino acids encoded by rpoB gene results in the molecular mechanism responsible for rifampicin resistance in Mycobacterium tuberculosis L-forms. It also proves that rpoB gene is diversiform.

Detection of mutation in embB gene of Mycobacterium tuberculosis from clinical isolates of tuberculous patients in China by means of reverse-dot blot hybridization

The relationship between embB mutation of Mycobacterium tuberculosis and ethambutol (EMB) resistance of the clinical isolates of tuberculous patients in China was investigated by reverse dot blot hybridization (RDBH) in addition to evaluating the clinical value with application of PCR-RDBH technique to detect EMB resistance. In the present study, the genotypes of the 258 bp fragments of embB genes from 196 clinical isolates of M. tuberculosis were analysed with RDBH and DNA sequencing. It was demonstrated that 60 out of 91 phenotypically EMB-resistant isolates (65.9%) showed 5 types of missense mutations at codon 306 of embB gene, resulting in the replacement of the Met residue of the wild type strain with Val, Ile or Leu residues. In these mutations, the GTP mutation (38/91, 41.8%) and the ATA mutation (16/91, 17.6%) were the most encountered genotypes. The embB mutation at codon 306 could also be found in 69 isolates of phenotypically EMB-sensitive but resistant to other anti-tuberculous drugs, but no such gene mutation could be found in 36 strains of drug-sensitive isolates. Meanwhile, the concordance with the results of DNA sequencing for one wide-type probe and 5 probes for specific mutations was 100% . It was concluded that the EMB-resistance occurring in most M. tuberculosis is due to appearance of embB mutation at codon 306, and the PCR-RDBH assay was proved to be a rapid, simple and reliable method for the detection of gene mutations, which might be a good alternative for the drug-resistance screening.

Detecting drug resistant genetic mutation among pneumoconiosis patients complicated with tuberculosis in Mycobacterium tuberculosis L-forms application of PCR-SSCP technique in Huainan mining district

Objective： To study the relationship between drug resistant genetic mutation and drug resistance in Mycobacterium tuberculosis L-form, discuss the internal relationship between drug resistances and drug-resistant related genes and explore the value of PCR- SSCP to clinical application. Methods： A total of 52 clinically isolated strains of tuberculosis L-form were collected among 97 pneumoconiosis patients complicated with tuberculosis. The gene mutations of katG, rpoB and rpsL were detected by PCR-SSCP, and the results were compared with those analyzed by traditional antimicrobial susceptibility test（AST）. Results： The gene muta- tion rates of katG, rpoB and rpsL by PCR-SSCP were respectively 57.70% （30/52）, 65.38% （32/52） and 40.38% （21/52）. The rate of reversion was 78.85%（41/52） and the result of drag-resistant genes was invariable. The results of AST showed that there were 40 （76.92%） multi-drug resistant strains in 52 clinically isolated strains. The number for three-drug resistant strain was 21 （40.38%） and that of two-drug resistant was 19（36.54%）, but only 12（23.08%） strains were one drug resistant. The rate of total drug-resistance was 100%, but there were 15 strains of allied mutation of three genes, 16 of two mutations and 6 of only one by PCR-SSCP. The coincidences were respectively 71.43%, 84.12% and 50.00%. Then there was no significant difference between the allied mutations of multi-drug resistant gene and the mutations of only one drug resistant gene （P 〉 0.05）. Conclusion： PCR-SSCP technique has a higher sensibility and specificity to detect the genes of katG, rpoB and rpsL in tuberculosis L-form among pneumoconiosis complicated with tuberculosis,and the detecting rate of two drug resistant strains and three drug resistant strains was higher. The combined application of PCR-SSCP and AST has advantages at earlier diagnosis and guidance of clinical medications.

尘肺结核患者Mycobacterium tuberculosis耐药基因突变研究

研究尘肺结核患者结核分枝杆菌(Mycobacterium tuberculosis,MTB)耐药基因突变与耐药性的关系。在97例尘肺结核患者痰中检出MTB菌株28株,采用PCR-SSCP法检测katG、rpoB和rpsL基因突变,并与采用常规药敏试验(AST)法检测的耐药结果进行对比分析。采用PCR-SSCP法检测katG、rpoB和rpsL基因,突变率分别为42.86%(12/28)、42.86%(12/28)和32.14%(9/28),采用AST法检测INH、RFP和SM,耐药率分别为64.23%(18/28)、60.71%(17/28)和53.57%(15/28),两者之间差异均无显著性(P>0.05)。其中多耐药株20例(71.43%),包括耐三种药物12例(42.86%),耐两种药8例(28.57%),单耐药株6例(21.43%),敏感株2例,耐药率92.86%。PCR-SSCP法检出3个基因联合突变8株,与AST法符合率为66.67%(8/12);2个基因突变5株,符合率为62.50%(5/8);单基因突变2株,符合率为33.33%(2/6)。结果表明:PCR-SSCP技术适用于MTB katG、rpoB和rpsL耐药基因突变的筛选,对指导尘肺结核患者临床用药上具有重要意义。

Rapid Detection of rpoB Gene Mutations in Rif-resistant M.tuberculosis Isolates by Oligonucleotide Microarray

Objective To detect the specific mutations in rpoB gene of Mycobacterium tuberculosis by oligonucleotide microarray. Methods Four wild-type and 8 mutant probes were used to detect rifampin resistant strains. Target DNA of M. tuberculosis was amplified by PCR, hybridized and scanned. Direct sequencing was performed to verify the results of oligonucleotide microarray Results Of the 102 rifampin-resistant strains 98 （96.1%） had mutations in the rpoB genes. Conclusion Oligonucleotide microarray with mutation-specific probes is a reliable and useful tool for the rapid and accurate diagnosis of rifampin resistance in M. tuberculosis isolates.

Prevalence and Risk Factors of Primary Drug-Resistant Tuberculosis in China

Objective To investigate the prevalence of primary drug-resistant tuberculosis（TB） and associated risk factors in China. We also explored factors contributing to the transmission of multidrug-resistant tuberculosis（MDR-TB）. Methods A total of 2794 representative, Mycobacterium tuberculosis isolates from treatment-naive patients were subjected to drug susceptibility testing, and risk factors for drug-resistant TB were analyzed. We also analyzed MDR-TB strain sublineages, drug-resistance-conferring mutations, and risk factors associated with clustered primary MDR strains. Results Among 2794 Mycobacterium tuberculosis isolates from treatment-naive patients, the prevalence of any resistance to first-line drugs was 33.2% and the prevalence of MDR-TB was 5.7%. We did not find any risk factors significantly associated with resistance to first-line drugs. The 93 primary MDR-TB isolates were classified into six sublineages, of which, 75（80.6%） isolates were the RD105-deleted Beijing lineage. The largest sublineage included 65（69.9%） isolates with concurrent deletions of RD105, RD207, and RD181. Twenty-nine（31.2%） primary MDR strains grouped in clusters; MDR isolates in clusters were more likely to have S531 L rpoB mutation. Conclusion This study indicates that primary drug-resistant TB and MDR-TB strains are prevalent in China, and multiple measures should be taken to address drug-resistant TB.

Low Doses of Rifampicin Used in New Tuberculosis Patients Correlated to Increased Frequency of Rifampicin-Resistance and Poorer Treatment Outcomes

The prognosis of patients with previously treated tuberculosis (TB) was suggested to be dependent on whether the initial treatment was in compliance with the established guidelines. The aim of this retrospective multicenter study was to determine the proportion of new TB patients who received standard doses of rifampicin in multiple provinces of China, and the relationship between low doses of rifampicin and frequency of rifampicin-resistance as well as treatment outcomes. A total of 713 new TB patients were treated with either once-daily dose of bulk anti-TB drugs (group I) or every other day combination blister packs of anti-TB drugs containing rifampicin (group II) at more than 30 TB treatment centers/hospitals in China. Treatment history, therapeutic doses of rifampicin, and information about patients were extracted from their medical records and analyzed, and rifampicin-resistance of isolates collected from patients following the treatment as well as treatment outcomes were compared between two treatment groups. Among 522 patients in treatment group I, 154 (29.5%) received standard and 363 (69.5%) received low doses of rifampicin;238 (45.6%) isolates were rifampicin-resistant, and 243 (46.6%) were successfully treated. Among 191 patients in treatment group II, 175 (91.6%) received standard and 15 (7.9%) received low doses of rifampicin;72 (37.7%) isolates were rifampicin-resistant, and 105 (55%) were successfully treated. When patients who received low doses of rifampicin were compared to others within the same treatment group, increased rates for rifampicin-resistance and treatment failure were observed. Results from this study showed that most new TB patients in treatment group I (69.5%) received low doses of rifampicin, and their treatment outcomes were worse than those in treatment group II, indicating that low doses of rifampicin used for the initial treatment of new TB patients were correlated to increased frequency of rifampicin-resistance and poorer treatment outcomes.

Activities of Biapenem against Mycobacterium tuberculosis in Macrophages and Mice

Objective To assess the activities of biapenem against multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis. Methods Biapenem/clavulanate(BP/CL) was evaluated for in vitro activity against Mycobacterium tuberculosis(Mtb) multidrug-resistant(MDR) isolates, extensively drug-resistant(XDR) isolates, and the H37 RV strain. BP/CL activity against the H37 Rv strain was assessed in liquid cultures, in macrophages, and in mice. Results BP/CL exhibited activity against MDR and XDR Mtb isolates in liquid cultures. BP/CL treatment significantly reduced the number of colony forming units(CFU) of Mtb within macrophages compared with control untreated infected macrophages. Notably, BP/CL synergized in pairwise combinations with protionamide, aminosalicylate, and capreomycin to achieve a fractional inhibitory concentration for each pairing of 0.375 in vitro. In a mouse tuberculosis infection model, the efficacy of a cocktail of levofloxacin + pyrazinamide + protionamide + aminosalicylate against Mtb increased when the cocktail was combined with BP/CL, achieving efficacy similar to that of the positive control treatment(isoniazid + rifampin + pyrazinamide) after 2 months of treatment. Conclusion BP/CL may provide a new option to clinically treat MDR tuberculosis.

Identification, Synthesis, Isolation and Spectral Characterization of Multidrug-Resistant Tuberculosis (MDR-TB) Related Substances

Several related substances were detected at trace level in (2R)-2,3-dihydro-2-methyl-6-nitro-2-[[4-[4-[4-(trifluoromethoxy)phenoxy]-1-piperidinyl] phenoxy] methyl]imidazo[2, 1-b]oxazole drug substance by a newly developed high-performance liquid chromatography method. All related substances were characterized rapidly but some impurities were found to be intermediates. Proposed structures were further confirmed by characterization using NMR, FT-IR, and HRMS techniques. Based on the spectroscopic data;unknown related sub-stances were characterized as 1-(Methylsulfonyl)-4-[4-(trifluoromethoxy) phenoxy]piperidine;4-{4-[4-(Tri-fluoromethoxy)-phenoxy]piperidin-1-yl}phenol and 4-{4-[4-(trifluoromethoxy)phenoxy]piperidin-1-yl}phenyl methane sulfonate;4-Bromophenyl methane sulfonate, Ethyl 3,6-dihydro-1(2H)-pyridine carboxylate, (2S)-3-(4-Bromophenoxy)-2-hydroxy-2-methylpropyl methane sulfonate, (2S)-3-(4-Bromophenoxy)-2-methylpropane-1,2-diyldimethane-sulfonate, (2S)-2-Methyl-3-(4-{4-[4-(trifluoromethoxy) phenoxy]-piperidin-1-yl} phenoxy)-propane-1,2-diyldimethane sulfonate, (S)-3-(4-Bromophenoxy)-2-methyl-propane-1,2-diol and corresponding Enantiomer, (2R)-2-[(4-Bromo-phenoxy)methyl]-2-methyloxirane and (2R)-2-[(4-bromophenoxy)methyl]-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazole. A possible mechanism for the formation of these related substances is also proposed.

Epidemiological perspective of drug resistant extrapulmonary tuberculosis

Tuberculosis(TB) remains one of the leading infectious diseases causing significant morbidity and mortality worldwide. Although, pulmonary TB is the most common presentation and is the main transmissible form of the disease, extrapulmonary TBalso significantly contributes to the burden of disease and can cause severe complications and disabilities. At present, the most serious issue with TB control programme is emergence of multi and extensively drug resistant Mycobacterium tuberculosis strain worldwide. As the number of drug resistant pulmonary TB is increasing around the world, the number of drug resistant TB with extrapulmonary manifestations are also on rise. However, there is surprisingly scant information in medical literatures on prevalence and impact of extrapulmonary drug-resistant TB. Here, we appraise the recent epidemiological studies that underpin the status and impact of drug resistance in TB cases with extrapulmonary manifestations.