Carvacrol Silver Nanoparticles - An Effective Antibacterial Against Carbapenem-Resistant Acinetobacter Isolates Unaided and With Meropenem

Abstract

Background: Acinetobacter species are a serious clinical challenge owing to their established resistance to carbapenems. This study aimed to explore Carvacrol silver nanoparticles’ activity against carbapenem-resistant Acinetobacter and their interaction with meropenem to develop effectual treatment. Methods: An in-vitro experimental study was conducted from February 2021 to January 2022. The minimum inhibitory concentration (MIC) of Carvacrol silver nanoparticles was checked using the broth macrodilution method. The results were further corroborated by performing the agar well diffusion method on 50 isolates of carbapenem-resistant Acinetobacter to observe the zone of inhibition (ZOI). The interaction of Carvacrol silver nanoparticles with meropenem (synergistic/additive/antagonistic) was assessed by checkerboard assay. SPSS vr24 was used. Kruskal-Wallis ANOVA with pair-wise comparison analysis was applied to compare different groups. p-value<0.05 was considered significant. Results: The study showed that older males were mostly affected and the majority of the isolates were from the tracheal secretions and collected from the Medical ICU. MIC of Carvacrol silver nanoparticles was found to be 0.04-0.16mg/ml. On agar well diffusion, the ZOI of Carvacrol silver nanoparticles was in the range of 0-20mm compared to meropenem (0) and colistin (0-14mm) with a p-value of 0.00. Checkerboard assay revealed additive interaction between Carvacrol silver nanoparticles and meropenem as the Fractional inhibitory concentration was calculated to be 1.25. Conclusion: Carvacrol silver nanoparticles have shown the potential ability to combat carbapenem-resistant Acinetobacter and may prove as an effective antibacterial agent in the future. Furthermore, the additive interaction of Carvacrol silver nanoparticles with meropenem points toward the possible revival of carbapenems against Acinetobacter

Keywords

• carvacrol
• acinetobacter
• carbapenems
• anti-bacterial agents