Effects of silver nanoparticles in combination with antibiotics on the resistant bacteria Acinetobacter baumannii

Abstract

Acinetobacter baumannii resistance to carbapenem antibiotics is a serious clinical challenge. As a newly developed technology, silver nanoparticles (AgNPs) show some excellent characteristics compared to older treatments, and are a candidate for combating A. baumannii infection. However, its mechanism of action remains unclear. In this study, we combined AgNPs with antibiotics to treat carbapenem-resistant A. baumannii (aba1604). Our results showed that single AgNPs completely inhibited A. baumannii growth at 2.5 μg/mL. AgNP treatment also showed synergistic effects with the antibiotics polymixin B and rifampicin, and an additive effect with tigecyline. In vivo, we found that AgNPs–antibiotic combinations led to better survival ratios in A. baumannii-infected mouse peritonitis models than that by single drug treatment. Finally, we employed different antisense RNA-targeted Escherichia coli strains to elucidate the synergistic mechanism involved in bacterial responses to AgNPs and antibiotics.

Keywords:

• Acinetobacter baumannii
• AgNPs
• synergistic
• antibiotic combination
• antisense RNA

Acknowledgments

The authors are very grateful to Professor Zhu Demei from Fudan University Huashan Hospital, who provided the resistant A. baumannii strain (aba1604) from clinical patients.

This work was funded by The National Major Scientific and Technological Special Project for “Significant New Drugs Development” (2012ZX09301002-003-007).

Disclosure

The authors report no conflicts of interest in this work.