Preparation and Evaluation of Rifampicin and Co-trimoxazole-loaded Nanocarrier against Brucella melitensis Infection

Background: Brucellosis or Malta fever is a contagious infection common between human and domestic animals. Many antibiotics are used for brucellosis treatment, but they are not efficient and put heavy burden on society. Co-trimoxazole and rifampicin are two candidates for brucellosis treatment. In this study, we aimed to enhance the efficacy of these antibiotics using designed nanoparticles. Methods: Different concentrations of co-trimoxazole and rifampicin were used for loading onto a nanostructure of synthesized monomethoxy poly(ethylene glycol)-oleate (mPEG-OA). The solubility, cytotoxicity, and efficacy of these nano-packed antibiotics on Brucella-infected murine phagocytic cells were examined, as compared with free antibiotics. Then the release nanoparticles was increased approximately 3.5 and 1.5fold, respectively, which is considerable in comparison with free insoluble ones. Despite acceptable loading percentage, the application of co-trimoxazole-loaded nanoparticle on Brucella-infected J774A.1 murine macrophage-like cells did not lead to reduction in the number of bacteria; however, the efficacy of rifampicin on Brucella-infected murine phagocytic cells enhanced. Conclusion: In the current study, the efficacy of rifampicin on reducing the number of Brucella melitensis increased by the novel synthesized nanostructure. In contrast, since co-trimoxazole efficacy did not enhance by loading onto nanoparticles, the co-trimoxazole inefficiency is most likely not due to its low penetration or insolubility, and probably there are other factors that remain to be clarified in the future investigations.