In vitro and in vivo synergistic effect of chrysin in combination with colistin against Acinetobacter baumannii

Abstract

<i>Acinetobacter baumannii</i> is an opportunistic pathogen that is primarily associated with nosocomial infections. With the rise in cases of acquired drug resistance, <i>A. baumannii</i> is gaining resistance to conventional antimicrobial drugs and even to the last line of antibiotics, such as colistin. Hence, the application of the synergistic combination of an antibiotic and a non-antibacterial agent is being contemplated as a new alternative therapeutic approach. Chrysin is a component of honey with anti-inflammatory and antioxidant properties. In this study, we evaluated the antibacterial activity of chrysin in combination with colistin against <i>A. baumannii</i> both <i>in vitro</i> and <i>in vivo</i>, as well as the cytotoxicity of chrysin with or without colistin. Our results revealed that chrysin and colistin exerted synergistic effects against <i>A. baumannii</i> by damaging the extracellular membrane and modifying the bacterial membrane potential. The chrysin/colistin combination group demonstrated an inhibitory effect on biofilm formation. In conclusion, it is expected that the synergy between these drugs can allow the use of a lower concentration of colistin for the treatment of <i>A. baumannii</i> infections, thereby reducing dose-dependent side effects. Thus, a combination therapy of chrysin/colistin may provide a new therapeutic option for controlling <i>A. baumannii</i> infections.