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Displaying publications 41 - 48 of 48 in total

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DNA markers for tuberculosis diagnosis

Chin KL, Sarmiento ME, Norazmi MN, Acosta A

Tuberculosis (Edinb), 2018 12;113:139-152.
PMID: 30514496 DOI: 10.1016/j.tube.2018.09.008

Tuberculosis (TB), caused by Mycobacterium tuberculosis complex (MTBC), is an infectious disease with more than 10.4 million cases and 1.7 million deaths reported worldwide in 2016. The classical methods for detection and differentiation of mycobacteria are: acid-fast microscopy (Ziehl-Neelsen staining), culture, and biochemical methods. However, the microbial phenotypic characterization is time-consuming and laborious. Thus, fast, easy, and sensitive nucleic acid amplification tests (NAATs) have been developed based on specific DNA markers, which are commercially available for TB diagnosis. Despite these developments, the disease remains uncontrollable. The identification and differentiation among MTBC members with the use of NAATs remains challenging due, among other factors, to the high degree of homology within the members and mutations, which hinders the identification of specific target sequences in the genome with potential impact in the diagnosis and treatment outcomes. In silico methods provide predictive identification of many new target genes/fragments/regions that can specifically be used to identify species/strains, which have not been fully explored. This review focused on DNA markers useful for MTBC detection, species identification and antibiotic resistance determination. The use of DNA targets with new technological approaches will help to develop NAATs applicable to all levels of the health system, mainly in low resource areas, which urgently need customized methods to their specific conditions.

Matched MeSH terms: Tuberculosis/drug therapy
Fulltext Prevalence and risk factors of anti-tuberculosis drug-induced hepatitis in Malaysia

Marzuki OA, Fauzi AR, Ayoub S, Kamarul Imran M

Singapore Med J, 2008 Sep;49(9):688-93.
PMID: 18830542

Tuberculosis (TB) affects one-third of the world's population. Anti-TB drugs with isoniazid, rifampicin and pyrazinamide are very effective but they can cause hepatotoxicity. Many risk factors have been recognised. Data on prevalence of anti-TB drug-induced hepatitis as well as the contributing risk factors are scarce in Malaysia. This observational case control study was designed to look at the prevalence and the risk factors of drug-induced hepatitis in our population.

Matched MeSH terms: Tuberculosis/drug therapy*
Fulltext Challenges in managing HIV in people who use drugs

Kamarulzaman A, Altice FL

Curr. Opin. Infect. Dis., 2015 Feb;28(1):10-6.
PMID: 25490106 DOI: 10.1097/QCO.0000000000000125

HIV management in people who use drugs (PWUD) is typically complex and challenging due to the presence of multiple medical and psychiatric comorbidities as well as social, physical, economic and legal factors that often disrupt the HIV continuum of care. In this review, we describe the individual, health systems and societal barriers to HIV treatment access and care retention for PWUD. In addition, the clinical management of HIV-infected PWUD is often complicated by the presence of multiple infectious and noninfectious comorbidities.

Matched MeSH terms: Tuberculosis/drug therapy*
Fulltext Attrition of TCR Vα7.2+ CD161++ MAIT cells in HIV-tuberculosis co-infection is associated with elevated levels of PD-1 expression

Saeidi A, Tien Tien VL, Al-Batran R, Al-Darraji HA, Tan HY, Yong YK, et al.

PLoS One, 2015;10(4):e0124659.
PMID: 25894562 DOI: 10.1371/journal.pone.0124659

Mucosal-associated invariant T (MAIT) cells are evolutionarily conserved antimicrobial MR1-restricted CD8(+) T cells co-expressing the semi-invariant TCR Vα7.2, and are numerous in the blood and mucosal tissues of humans. MAIT cells appear to undergo exhaustion in chronic viral infections. However, their role in human immunodeficiency virus type 1 (HIV-1) mono-infection and HIV/tuberculosis (TB) co-infection have seldom been elaborately investigated. We conducted a cross-sectional study to investigate the frequencies and phenotypes of CD161(++)CD8(+) T cells among anti-retroviral therapy (ART)/anti-TB therapy (ATT) treatment-naïve HIV/TB co-infected, ART/TB treated HIV/TB co-infected, ART naïve HIV-infected, ART-treated HIV-infected patients, and HIV negative healthy controls (HCs) by flow cytometry. Our data revealed that the frequency of MAIT cells was severely depleted in HIV mono- and HIV/TB co-infections. Further, PD-1 expression on MAIT cells was significantly increased in HIV mono- and HIV-TB co-infected patients. The frequency of MAIT cells did not show any significant increase despite the initiation of ART and/or ATT. Majority of the MAIT cells in HCs showed a significant increase in CCR6 expression as compared to HIV/TB co-infections. No marked difference was seen with expressions of chemokine co-receptor CCR5 and CD103 among the study groups. Decrease of CCR6 expression appears to explain why HIV-infected patients display weakened mucosal immune responses.

Matched MeSH terms: Tuberculosis/drug therapy
Fulltext Aberrant Inflammasome Activation Characterizes Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome

Tan HY, Yong YK, Shankar EM, Paukovics G, Ellegård R, Larsson M, et al.

J Immunol, 2016 05 15;196(10):4052-63.
PMID: 27076678 DOI: 10.4049/jimmunol.1502203

Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) complicates combination antiretroviral therapy (cART) in up to 25% of patients with HIV/TB coinfection. Monocytes and IL-18, a signature cytokine of inflammasome activation, are implicated in TB-IRIS pathogenesis. In this study, we investigated inflammasome activation both pre- and post-cART in TB-IRIS patients. HIV/TB patients exhibited higher proportions of monocytes expressing activated caspase-1 (casp1) pre-cART, compared with HIV patients without TB, and patients who developed TB-IRIS exhibited the greatest increase in casp1 expression. CD64(+) monocytes were a marker of increased casp1 expression. Furthermore, IL-1β, another marker of inflammasome activation, was also elevated during TB-IRIS. TB-IRIS patients also exhibited greater upregulation of NLRP3 and AIM2 inflammasome mRNA, compared with controls. Analysis of plasma mitochondrial DNA levels showed that TB-IRIS patients experienced greater cell death, especially pre-cART. Plasma NO levels were lower both pre- and post-cART in TB-IRIS patients, providing evidence of inadequate inflammasome regulation. Plasma IL-18 levels pre-cART correlated inversely with NO levels but positively with monocyte casp1 expression and mitochondrial DNA levels, and expression of IL-18Rα on CD4(+) T cells and NK cells was higher in TB-IRIS patients, providing evidence that IL-18 is a marker of inflammasome activation. We propose that inflammasome activation in monocytes/macrophages of HIV/TB patients increases with ineffective T cell-dependent activation of monocytes/macrophages, priming them for an excessive inflammatory response after cART is commenced, which is greatest in patients with TB-IRIS.

Matched MeSH terms: Tuberculosis/drug therapy
Genomic plasticity between human and mycobacterial DNA: A review

Danjuma L, Ling MP, Hamat RA, Higuchi A, Alarfaj AA, Marlina, et al.

Tuberculosis (Edinb), 2017 12;107:38-47.
PMID: 29050770 DOI: 10.1016/j.tube.2017.03.006

Mycobacterium tuberculosis has a remarkable ability of long-term persistence despite vigorous host immunity and prolonged therapy. The bacteria persist in secure niches such as the mesenchymal stem cells in the bone marrow and reactivate the disease, leading to therapeutic failure. Many bacterial cells can remain latent within a diseased tissue so that their genetic material can be incorporated into the genetic material of the host tissue. This incorporated genetic material reproduces in a manner similar to that of cellular DNA. After the cell division, the incorporated gene is reproduced normally and distributed proportionately between the two progeny. This inherent adoption of long-term persistence and incorporating the bacterial genetic material into that of the host tissue remains and is considered imperative for microbial advancement and chemotherapeutic resistance; moreover, new evidence indicates that the bacteria might pass on genetic material to the host DNA sequence. Several studies focused on the survival mechanism of M. tuberculosis in the host immune system with the aim of helping the efforts to discover new drugs and vaccines against tuberculosis. This review explored the mechanisms through which this bacterium affects the expression of human genes. The first part of the review summarizes the current knowledge about the interactions between microbes and host microenvironment, with special reference to the M. tuberculosis neglected persistence in immune cells and stem cells. Then, we focused on how bacteria can affect human genes and their expression. Furthermore, we analyzed the literature base on the process of cell death during tuberculosis infection, giving particular emphasis to gene methylation as an inherited process in the neutralization of possibly injurious gene components in the genome. The final section discusses recent advances related to the M. tuberculosis interaction with host epigenetic circuitry.

Matched MeSH terms: Latent Tuberculosis/drug therapy
Pattern of first- and second-line drug resistance among pulmonary tuberculosis retreatment cases in Pakistan

Javaid A, Hasan R, Zafar A, Chaudry MA, Qayyum S, Qadeer E, et al.

Int J Tuberc Lung Dis, 2017 03 01;21(3):303-308.
PMID: 28225340 DOI: 10.5588/ijtld.16.0444

BACKGROUND: Drug resistance in general, and multidrug-resistant tuberculosis (MDR-TB) in particular, threatens global tuberculosis (TB) control efforts. Population-based estimates of drug resistance are needed to develop strategies for controlling drug-resistant TB in Pakistan.
OBJECTIVE: To obtain population-based data on Mycobacterium tuberculosis drug resistance in Pakistan.
METHODS: To obtain drug resistance data, we conducted a population-based study of TB cases in all provinces of Pakistan. We performed culture and drug susceptibility testing on M. tuberculosis isolates from patients with a prior history of anti-tuberculosis treatment (retreatment cases) from all over the country.
RESULTS: Of 544 isolates from previously treated cases, 289 (53.1%) were susceptible to all first-line drugs, 255 (46.9%) were resistant to at least one anti-tuberculosis drug and 132 (24.3%) were MDR-TB. Among MDR-TB isolates, 47.0% were ofloxacin (OFX) resistant. Extensively drug-resistant TB was found in two (0.4%) isolates.
CONCLUSION: Prevalence of drug resistance in retreatment isolates was high. The alarmingly high prevalence of OFX resistance among MDR-TB isolates may threaten the success of efforts to control and treat MDR-TB.

Matched MeSH terms: Extensively Drug-Resistant Tuberculosis/drug therapy*
Fulltext Antimycobacterial susceptibility evaluation of rifampicin and isoniazid benz-hydrazone in biodegradable polymeric nanoparticles against Mycobacterium tuberculosis H37Rv strain

Hakkimane SS, Shenoy VP, Gaonkar SL, Bairy I, Guru BR

Int J Nanomedicine, 2018;13:4303-4318.
PMID: 30087562 DOI: 10.2147/IJN.S163925

INTRODUCTION: Tuberculosis (TB) is the single largest infectious disease which requires a prolonged treatment regime with multiple drugs. The present treatment for TB includes frequent administration of a combination of four drugs for a duration of 6 months. This leads to patient's noncompliance, in addition to developing drug-resistant strains which makes treatment more difficult. The formulation of drugs with biodegradable polymeric nanoparticles (NPs) promises to overcome this problem.
MATERIALS AND METHODS: In this study, we focus on two important drugs used for TB treatment - rifampicin (RIF) and isoniazid (INH) - and report a detailed study of RIF-loaded poly lactic-co-glycolic acid (PLGA) NPs and INH modified as INH benz-hydrazone (IH2) which gives the same therapeutic effect as INH but is more stable and enhances the drug loading in PLGA NPs by 15-fold compared to INH. The optimized formulation was characterized using particle size analyzer, scanning electron microscopy and transmission electron microscopy. The drug release from NPs and stability of drug were tested in different pH conditions.
RESULTS: It was found that RIF and IH2 loaded in NPs release in a slow and sustained manner over a period of 1 month and they are more stable in NPs formulation compared to the free form. RIF- and IH2-loaded NPs were tested for antimicrobial susceptibility against Mycobacterium tuberculosis H37Rv strain. RIF loaded in PLGA NPs consistently inhibited the growth at 70% of the minimum inhibitory concentration (MIC) of pure RIF (MIC level 1 µg/mL), and pure IH2 and IH2-loaded NPs showed inhibition at MIC equivalent to the MIC of INH (0.1 µg/mL).
CONCLUSION: These results show that NP formulations will improve the efficacy of drug delivery for TB treatment.

Matched MeSH terms: Tuberculosis/drug therapy