In-vivo and In-vitro Anti-Acinetobacter baumannii Activity of Citrate-Capped Silver Nanoparticles

Silver nanoparticles (AgNPs) are of potential interest because of their effective antibacterial and antiviral activities. Capping agents are used for exhibiting a better antibacterial activity than uncapped Ag NPs. There are very few reports that have shown the usage of AgNPs for in-vivo antibacterial therapy. Citrate-capped silver nanoparticles were synthesized chemically by citrate reduction method; the size of Cit-AgNPs was determined by an atomic force microscope (AFM) and was between 15 90 nm. Acinetobacter baumannii (A. baumannii) isolates were the only sensitive species to CitAgNPs. MICs and MBC of Cit-AgNPs were determined by using A. baumannii. The results showed an additive effect of Cit-AgNPs. Four mice groups were infected with a sub-lethal dose of A. baumannii intraperitoneally, IP. The single daily dose of Cit-AgNPs and imipenem plus Cit-AgNPs combination were administered IP. Imipenem and phosphate buffer saline (PBS) was used as positive control and negative control, respectively. Interestingly, only the PBS-treated group showed growth of A. baumannii in the liver and spleen of sacrificed mice. Histopathologically, Cit-AgNPs showed antibacterial activity and had an additive effect when combined with imipenem in vivo and in vitro. Moreover, the Cit-AgNPs showed dose-dependent activity and the organs differed in the illumination of the toxicity effect of Cit-AgNPs even after high dose administration. In conclusion, Cit-capped AgNPs had antibacterial activity against multiple drug resistant (MDR) A. baumannii but not against K. pneumoniae and E. coli. Cit-capped AgNPs increased the inhibition zone of imipenem in additive effect; the minimum inhibitory concentration and the minimum bactericidal concentration of Citcapped AgNPs were relatively low. Cit-capped AgNPs eliminated A. baumannii infection in vivo when it was given alone or in combination with imipenem. The cytotoxicity of Cit-AgNPs was dosedependent and the organs differed in the illumination of the inflammatory effect of Cit-AgNPs after high dose administration. It is not recommended to use Cit-capped AgNPs systemically despite their valuable additive antibacterial effect especially with a high dose and the combination with imipenem, Topical administration needs to be evaluated.