Nowadays, there is an increasing concern about the emergence and re-emergence of drug resistance to many pathogens such as bacterial and fungal strains [1]. Therefore, the development of novel antimicrobial compounds to combat resistant pathogens is a research of high priority. In relation to its broad spectrum of efficient activity and lower costs, nanosilver particles based on antimicrobial agents are excellent candidates for therapeutic purpose. However, it is well known that size of NPs influence the physicochemical properties and mechanisms of toxic action and in consequence the bioavailability [2]. A range of analytical techniques are available for providing information on particle size distributions, including microscopy approaches [3], chromatography [4], centrifugation [5], laser scattering [6], filtration [7], spectroscopic [8] and flow field flow fractionation [9]. The present work has been focused on the antimicrobial activity of silver nanoparticles synthetized from acidophilic actinobacteria strain CGG11n and their physicochemical characteristics using different techniques. Moreover, the interaction of these nanoparticles with antibiotics in different combination on bacterial strains was evaluated.