ABSTRACT
             Background and objectives: Antimicrobial resistance is a serious threat to global public health. The overuse and misuse of antibiotics are the most important contributing factors to development of antibiotic resistance. Thus, there is an urgent need to identify and discover new compounds against drug-resistant microorganisms. We have previously synthesized new series of 3-substituted 5H-(1,2,4)triazolo(3',4':2,3) (1,3,4)thiadiazino(5,6-b)quinoxaline derivatives (4a-4f). Here, we evaluate the antimicrobial activity of these derivatives against methicillin-resistant Staphylococcus aureus, S. aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Candida tropicalis and Candida krusei.
             Methods: The agar well diffusion and agar dilution methods were used for determining inhibition zone diameter and minimum inhibitory concentration during preliminary evaluation of antimicrobial activity.
             Results: All synthesized compounds exhibited antibacterial and antifungal activity against the tested microorganisms.
             Conclusion: Our findings indicate the antimicrobial potential of the six novel synthetic triazolo thiadiazin quinoxaline compounds.
             Keywords: Antimicrobial, Anti-bacterial agents, Antifungal agents, Triazolo, Thiadiazin, Quinoxaline.

Background and Objective: The prevalence of the infections caused by Candida species has led to a significant increase in their resistance to antifungal compounds. The aim of this study was to i) investigate drug resistance ii) evaluate the incidence of Candida albicans drug resistance pattern in the vaginal samples of women referring to health centers of Qom province, and iii) examine the effect of Zn nanoparticles combined with fluconazole against C. albicans isolates.
           Methods: This experimental, descriptive study was performed on 120 patients of candidiasis. In order to identify Candida albicans, direct experiments, differential culture, Germ tube test and sugar assimilation test (API20C kit) were conducted. The effect of different antifungal drugs and zinc nanoparticles and the synergistic effect of fluconazole with zinc nanoparticles were investigated by disk diffusion method. Minimum Inhibitory Concentration (MICs) of all cases was further specified.
           Results: Of the 120 samples, 50 (41.6%) were identified as Candida albicans. These strains were resistant to certain antifungal drugs while others were semi-sensitive and sensitive. The lowest and the highest mean diameter of inhibition zone in all Candida albicans isolates belonged to ketoconazole (15.64 mm) and fluconazole nano-ZnO (26.76mm), respectively. The lowest and the highest MICs were observed in fluconazole- nano-ZnO and nano-ZnO, respectively.
           Conclusion: The synergistic effect of Zn nanoparticles with fluconazole can be conducive to the treatment of vaginal candidiasis.