Antimicrobial Activity of Silver Nanoparticles with Antibiotics Against Clinically Isolated Acinetobacter baumannii

Antibiotic-resistant bacteria are among the major healthcare problem worldwide and Acinetobacter baumannii is a leading threat among them. In this study, the combined effects of different antibiotics with silver nanoparticles (AgNPs) were assessed against the growth of a clinical isolate of A. baumannii. The bacterial strain was isolated from a hospitalized burned patient in Sulaimanyah- Iraq. Identification of the isolated bacterium was done based on the partial sequence of the 16S rRNA gene and phylogenetic analysis. The growth of the bacterium was totally inhibited by AgNPs at the concentration of (0.2 mg/ml).  AgNPs treatment showed a partial synergistic effect with azithromycin (Fractional Inhibitory Concentration Index (FICI) = 0.6) and an additive effect with kanamycin (FICI = 1.67). Not a significant difference in the antimicrobial activities of either ampicillin or tetracycline was observed when they used alone or in combination with AgNPs. Overall, this study may provide a promising future use of azithromycin with AgNPs to treat A. baumannii superficial infections; however, a combination of kanamycin with AgNPs together should be avoided.