Tuberculosis (TB) is an ancient disease caused by Mycobacterium tuberculosis (MTB), which remains a major cause for morbidity and mortality in several developing countries. Most drug-resistant MTB clinical strains are resistant to isoniazid (INH), a first-line anti-TB drug. Mutation in KatG, a catalase-peroxidase, of MTB is reported to be a major cause of INH resistance. Normally upon activation by KatG, INH is converted to an active intermediate which has antimycobacterial action in MTB. This INH intermediate in the presence of NADH forms INH-NAD adduct which inhibits inhA (2-trans-enoyl-acyl carrier protein reductase) of MTB, thus blocking the synthesis of mycolic acid, a major lipid of the mycobacterial cell wall. In this docking study, the high binding affinity of INH-NAD adduct towards InhA was observed in comparison with INH alone. In this study, two resistant mutants of KatG (S315T and S315N) were modeled using Modeller9v10 and docking analysis with INH was performed using AutoDock4.2 and the docking results of these mutants were compared with the wild type KatG. Docking results revealed the formation of a single hydrogen (H) bond between the secondary amine nitrogen (–NH) of INH with Thr or Asn residues in place of Serine at 315 position of KatG mutant strains respectively, whereas in the case of the wild type, there was no H-bond formation observed between INH and Ser315. The H-bond formation may prevent free radical formation by KatG in mutant strains thus the development of resistance to the drug. This in silico evidence may implicate the basis of INH resistance in KatG mutant strains.

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Aims: The present meta-analysis aims to assess the evidence regarding the diagnostic accuracy and performance characteristics of the colorimetric redox indicator (CRI) assay with a special emphasis on the use of the resazurin microtiter assay (REMA) for determination of primary anti-tuberculosis drug resistance. Subject and methods: By updating previous literature searches in Medline PubMed, ISI Web, Web of Science and Google academic databases of the REMA test for determination of primary anti-tuberculosis drug resistance, this meta-analysis includes 14 studies for isoniazid (INH); 15 studies for rifampicin (RIF); 6 studies for streptomycin (STR); and 5 studies for ethambutol (EMB). SROC curve analysis was performed for meta-analysis and diagnostic accuracy was summarized. Results: Pooled sensitivity was 96% (94–98%) for INH, 97% (95–98%) for RIF, 92% (87–96%) for EMB and 92% (88–95%) for STR. Pooled specificity for INH, RIF, EMB and STR was 96% (95–98%), 99% (98–99%), 86% (81–89%) and 90% (87–93%), respectively. Susceptibility testing results had been obtained in 8–9days. Conclusion: In conclusion, REMA seems to be a reliable test for the determination of multi-drug resistant (MDR) isolates in laboratories with limited resources. However, few studies for STR and EMB have been found, and cost-effectiveness studies need to be determined to recommend its widespread use.

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Sarcoidosis is a granulomatous inflammatory disease that is induced by unknown antigen(s) in a genetically susceptible host. Although the direct link between Mycobacterium tuberculosis (MTB) infection and sarcoidosis can be excluded on the basis of current knowledge, non-infectious mechanisms may explain the causative role of mycobacterial antigens. Ever since sarcoidosis was first described, its relationship with tuberculosis (TB) has been under-investigated. Whereas some researchers consider sarcoidosis and TB as two examples of the same disease process, others have rejected mycobacteria as playing any causative role in sarcoidosis. Whether they are linked causally or not, clinical evidence makes a differential diagnosis between the two conditions very challenging, particularly in countries with high burden of TB. The present study analyzes the relationship between sarcoidosis and TB and its implications in clinical practice. The coincidence of TB and sarcoidosis and the higher incidence of mycobacterial DNA in biological samples of sarcoid patients have been reported by many authors. In addition, new evidence of a similarity in MTB phenotype in sarcoidosis is provided. Overall, these observations suggest that TB and sarcoidosis may not only share the same etiology, but may even be different aspects of one disease.

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Introduction: Mycobacterium marinum has emerged as a suitable species for induction of tuberculosis-like disease in zebrafish, and various zebrafish models (larval and adult) for drug screening have been proposed in the literature. It is believed that an adult zebrafish model is more useful in drug screening because, apart from assessment of efficacy, one can obtain data on dosage, pharmacokinetics and overall health improvement. This study suggests a simple, cost-effective and resource-efficient protocol for screening of anti-tuberculosis drugs. Methods: The parameters used for assessment of infection as well as anti-bacterial response were: (a) bacterial count; and (b) body weight change. An optimization study was conducted to establish the concentration of bacteria required to produce a reproducible phenotype of tuberculosis (TB). A negative control (Amoxicillin) and anti-mycobacterial drugs (Isoniazid, Rifampicin, Moxifloxacin, Ethambutol and Isoniazid+Rifampicin) were used for validation of the protocol. All the drugs were administered orally. Results: An intra-peritoneal inoculation of 0.75 million bacteria/fish was optimized for the model. All the anti-tuberculosis drugs showed efficacy in this model, whereas the negative control did not show any signs of reversing the parameters of M. marinum infection. Discussion: Adult zebrafish model of M. marinum-induced tuberculosis has not been fully exploited as a drug screening tool. In the present report, a protocol is suggested that is simple, reproducible and resource-efficient for screening of anti-tuberculosis agents. This protocol is an attempt to refine the published protocols and use this model as a surrogate model of human TB for the purpose of drug screening.

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Background: Health care workers (HCW) in low and middle income countries are at high risk of nosocomial tuberculosis infection. Periodic screening of health workers for both TB disease and infection can play a critical role in TB infection control. Occupational health programs that implement serial tuberculin skin testing (TST) are advised to use a two-step baseline TST. This helps to ensure that boosting of waned immune response is not mistaken as new TB infection (i.e. conversion). However, there are no data on safety of the two-step TST in the Indian context where HCWs are repeatedly exposed. Materials and methods: Nursing students were recruited from 2007 to 2009 at the Christian Medical College and Hospital, Vellore, India. Consenting nursing students were screened with a baseline two-step TST at the time of recruitment. From 2007 to 2008 adverse events were recorded when reported during the TST reading (Cohort A). Nurses recruited in the final study year (2009) answered an investigator administered questionnaire assessing all likely side-effects Cohort B). This information was extracted from the case report forms and analysed. Results: Between 2007 and 09, 800 trainees consented to participate in the annual TB screening study and 779 did not have a past history of TB or recall a positive TST and were selected to administer TST. Of these, 755 returned for reading the result and had complete data and were included for the final analysis – 623 subjects in (cohort A) and 132 in (cohort B). These were included for the final analysis. In cohort A only 1.3% reported adverse events. In cohort B, as per the investigator administered questionnaire; 25% reported minor side effects. Itching and local pain were the most common side effects encountered. There were no major adverse events reported. In particular, the adverse events were similar in the second step of the test and not more severe. Conclusion: Screening of HCWs with two-step TST for LTBI is simple and safe, and hence suitable for wide scale implementation in high-burden settings such as India.

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This study was carried out in Khartoum State during the period from January 2011 to December 2013 to improve the rate of detection of Mycobacterium tuberculosis (MTB) in children with symptoms of tuberculosis (TB) infection using different conventional and advanced diagnostic techniques. One hundred and ninety-seven specimens of gastric lavage and sputum were collected from different hospitals in Khartoum State, including Elbolok Hospital, Jafar Ibn Owf Hospital, Elasha'ab Teaching Hospital, Soba University Hospital and Academy Charity Hospital. All children participating in the study were subjected to the Mantoux test after obtaining appropriate consent injected by 5 tuberculin units of tuberculin purified protein derivative, and the results were recorded after three days. Specimens were decontaminated and inoculated on Lowenstein–Jensen media according to the modified Petroff's method. Two smears were prepared and stained by Ziehl–Neelsen stain and Auramine fluorescent dye; bacterial DNA was extracted from each specimen by using phenol chloroform method, and then the Polymerase Chain Reaction technique was adopted to detect Insertion Sequence IS6110 gene of MTB in these specimens. This study showed that the positive results for TST, ZN, Auramine, Culture and PCR were 86 (43.7%), 16 (8.1%), 22 (11.2%), 32 (16.2%) and 35(17.8%), respectively. The study concluded that the PCR technique is the most sensitive and specific technique for a quick identification of MTB in gastric lavage and sputum from children who are unable to expectorate a good quality sputum sample or who are diagnosed as negative using conventional diagnostic methods.

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Background: Bernard–Soulier Syndrome (BSS) is a rare congenital bleeding disorder characterized by thrombocytopenia. BSS causes bruising, epistaxis, gingival bleeding hemorrhage, post-partum bleeding, gastrointestinal bleeding and post-traumatic hemorrhage, but there is no report of hemoptysis in BSS. Case report: A 14-year-old girl was referred to this center due to massive hemoptysis. Her chest X-ray revealed complete collapse of the left lung. Rigid bronchoscopy was performed and the intrabronchial clots were removed. Smear and culture of direct sputum was positive for Mycobacterium tuberculosis. She received anti-tuberculosis treatment. During treatment, she developed massive vaginal bleeding, because of drug interaction between rifampin and low dose contraceptive (LD), which she had been taking for control of massive menstrual bleeding. Her vaginal bleeding was controlled by platelet infusion and recombinant factor 7 infusion. After two months of anti-TB treatment, the sputum smear and culture examination became negative. One year after treatment, the pulmonary tuberculosis was completely cured and no hemoptysis occurred. Conclusion: When hemoptysis occurs in patients with BSS, other differential diagnoses should also be considered.

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Nontuberculous mycobacteria (NTM) have been reported to cause opportunistic infections with increasing frequency, especially in immunocompromised patients. Water plays a major role in the epidemiology of nontuberculous mycobacterial infection in humans, as it is one of the natural sources for transmission of this group of organisms. The current study focused on determining the occurrence of NTM in different aquatic sources of Sri Lanka by using phenotypic tests and polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis of the rpoβ gene. Of 290 water samples, 45 (15%) were positive for NTM on culture. The percentage of mycobacteria identified at species level by phenotypic tests and PCR–RFLP analysis were 44% (20/45) and 73% (33/45), respectively. The frequency of isolation of mycobacteria from aquarium water, surface water, ground water and chlorinated water were 29% (20/70), 26% (20/76), 5% (4/76) and 1% (1/68), respectively. Eleven different NTM species were identified by PCR–RFLP analysis. M. fortuitum type I was the most frequently isolated species from all the four water sources. The current study suggests that water is an environmental source harboring NTM, a potential public health hazard especially for those with immunodeficiency.

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Decontamination by modified Petroff's method is being practiced in many laboratories carrying out Mycobacterium tuberculosis culture and drug susceptibility testing. The method exposes mycobacteria to 4% sodium hydroxide for 30 min. However, laboratories in developing countries with limited resources might be using a type of centrifuge that does not open during power failures and exposes the mycobacteria to alkali for longer periods. Out of 28 smear-positive specimens processed, 85.7%, 85.7% and 60.7% of specimens showed a positive culture after exposure to alkali for 0.5, 1.0 and 72h. Laboratories compelled to expose the mycobacteria for a longer duration of time can still attempt isolation for culture as only a small amount of bacteria are needed for culture positivity.

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Setting: Namibia faces a high burden of tuberculosis (TB) and HIV-infection. In 2011, 50% of the TB patients were co-infected with HIV. While all patients co-infected with TB and HIV are eligible for antiretroviral treatment (ART), only 54% were reported to have received ART according to national data. Objective: To explore the perspective of healthcare professionals on barriers to access to ART for HIV-positive TB patients. Design: Nine semi-structured qualitative interviews were conducted with healthcare professionals from TB and HIV services in Windhoek in 2012 to investigate access barriers to ART for HIV-positive TB patients in Namibia. Results: Many barriers known from other African countries were also present in Namibia. The barriers rated as most important were: staff shortage (health system level); limited training (healthcare worker level); and fear of stigma and discrimination (patient/community level). Direct treatment costs and limited availability of antiretroviral medication were not observed as barriers. Interference with TB treatment and ART by some Pentecostal churches was revealed as an important barrier that has not yet received sufficient attention. Conclusion: The study identified access barriers to ART for HIV-positive TB patients and their relevance in Namibia. The findings provide evidence for tailored interventions to increase ART-uptake among HIV-positive TB patients.

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In this present study for the first time the authors are reporting the isolation of Mycobacterium gilvum from the accumulated water in the drain connected to the bathing place of leprosy patients residing in an endemic region. The identification and characterization of this isolate was carried out by various conventional and molecular tests, including 16S rDNA sequencing. These findings might shed further light and association with amoeba in the leprosy endemic area of this rare Mycobacterium species.

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