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Despite the low expensive and effective four-drug treatment regimen (isoniazid, rifampicin, pyrazinamide and ethambutol) was introduced 40 years ago, TB continues to cause considerable morbidity and mortality worldwide. In 2015, the WHO estimated a total of 10.4 million new tuberculosis (TB) cases worldwide. Currently, the increased number of multidrug-resistant (MDR-TB), extensively-drug resistant (XDR-TB) and in some recent reports, totally drug-resistant TB (TDR-TB) cases raises concerns about this disease. MDR-TB and XDR-TB have lower cure rates and higher mortality levels due to treatment problems. Novel drugs and regimens for all forms of TB have emerged in recent years. Moreover, scientific interest has recently increased in the field of host-directed therapies (HDTs) in order to identify new treatments for MDR-TB. In this review, we offer an update on the discovery of new drugs for TB therapy with a glance at molecular mechanisms leading to drug resistance in Mycobacterium tuberculosis . [ABSTRACT FROM AUTHOR]

Objectives Multidrug-resistant tuberculosis (MDR-TB) is a global problem that many countries are challenged with. Rapid and accurate detection of MDR-TB is critical for appropriate treatment and controlling of TB. The aim of the present study was to evaluate the TaqMan allelic discrimination without minor groove binder (MGB) as a rapid, efficient, and low-cost method for detection of drug resistant strains of Mycobacterium tuberculosis . Methods A total of 112 M. tuberculosis isolates from cases with diagnosed TB were subjected to drug susceptibility testing (DST), using the proportion method. Resistant isolates were tested for characterization of mutations in the rpoB and KatG genes by TaqMan genotyping. Results Of 112 M. tuberculosis isolates for which DST was performed, three, one, and two isolates were MDR, rifampin (RIF) resistant, and isoniazid (INH) resistant, respectively. According to the threshold cycle (Ct) and curve pattern of mutants, TaqMan probes detect all of the mutations in the analyzed genes ( katG 315, AGC→ACC, rpoB 531, TCG→TTG, and rpoB 531, TCG→TGG). Conclusion The present study suggests that drug-resistant strains of M. tuberculosis can be detected by pattern’s curve or Ct with TaqMan probes without MGB in real-time polymerase chain reaction (PCR). [ABSTRACT FROM AUTHOR]

Background: The spread of multidrug-resistant tuberculosis (MDR-TB) is a major public health problem worldwide. Although drug resistance is common in some countries and rare in others, the extent of this condition is not precisely known in Iran. Methods: We searched several databases including PubMed, Web of Science, Scopus, Iran Medex, and Scientific Information Database to identify studies addressing drug-resistant tuberculosis in Iran. A total of 19 reports published from different regions of Iran from March 1999-May 2013 were included in this study. Results: The meta-analyses revealed that 23% (95% confidence interval [CI], 21.8-24.2) of new cases and 65.6% (95% CI, 62.5-68.5) of previously treated cases were resistant to at least 1 drug. Furthermore, MDR-TB was found in 5.1% (95% CI, 4.4-5.8) of new cases, whereas it was found in 33.7% (95% CI, 30.8-36.7) of retreatment cases. The highest rate of resistance in new and previously treated cases was seen against streptomycin (19%) and isoniazid (47%), respectively. Conclusion: The results of the present study underscore the need for further enforcement of TB control strategies. Drug susceptibility testing, establishing advanced diagnostic facilities, and continuous monitoring of drug resistance are recommended for prevention and control of MDR-TB. [ABSTRACT FROM AUTHOR]

• Chitosan-coated selenium nanoparticles (SeNPs) were synthesized using the chemical reduction method. • The combined use of methylene blue-induced photo-dynamic therapy (PDT) and seNPs significantly reduced colony-forming units of one-day-old E. faecalis biofilms compared to the control group (P value < 0.05). • PDT in combination with seNPs had the most antibacterial effect on root canal E. faecalis biofilms at both 200 and 400 µm depth of dentine tubules (P value < 0.001). Selenium Nanoparticles (SeNPs) were reported as an agent that may enhance the effectiveness of Photodynamic Antimicrobial Chemotherapy (PACT). This in vitro study evaluates the effect of SeNPs on the efficacy of Methylene Blue (MB)-induced PACT against the biofilm formated in 96-well plates and the dentine tubule biofilm of Enterococcus faecalis. Chitosan coated SeNPs were synthesized using chemical reduction method and were characterized by Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS). Twenty-four-hour biofilms of E. faecalis were developed on 96-well plates and treated with SeNPs, MB, and Light-Emitting Diode (LED). Also, three-week biofilms of E. faecalis were formed on 67 specimens of dentinal tubules, and the antibacterial effects of MB+SeNPs on these biofilms were studied. The average hydrodynamic diameter of SeNPs was 80/3 nm according to DLS measurement. The combined use of MB and SeNPs significantly reduced Colony-Forming Units (CFUs) of one-day-old E. faecalis biofilms in comparison with the control group (P value < 0.05). Besides, combination therapy had the most antibacterial effect on root canal E. faecalis biofilms at both 200 and 400 µm depths of dentine tubules (P value < 0.001). Of note, about 50% of human fibroblast cells survived at a concentration of 128 µg/ml of SeNPs, compared to the control group. The results demonstrated that the photodynamic therapy modified by SeNPs could be an effective disinfection alternative to the destruction of E. faecalis biofilms and root canal treatment. [ABSTRACT FROM AUTHOR]