Evaluation of Antimicrobial Activity of Cinnamaldehyde against Carbapenem-Resistant Acinetobacter baumannii Nosocomial Isolates

Abstract

The emergent and rapid spread of carbapenem-resistant A. baumannii isolates poses a severe threat to public health. Thus, the growing interest in new therapies based on natural products is the basic and primary source for the emergence of new antimicrobials. The aim of this study was to evaluate the antimicrobial activity of cinnamaldehyde against carbapenem-resistant A. baumannii nosocomial strains (n=47) isolated from patients in four teaching hospitals at Ceará, Brasil. Phenotypic identification and susceptibility to different antimicrobials were determined by VITEK®2, additionally gene blaOXA-51 was amplified by PCR on all presumptively identified as A. baumannii and the clinical characteristics were analyzed. The MIC of the cinnamaldehyde was performed according to microdilution methodology in standard 96-well polystyrene plates, according to the CLSI recommendations and MBC was determined. The MIC ranged from 125 to 500 μg/mL (Mean = 210.93 ± 58.55) and the MBC for most isolates was 250 μg/mL (Mean = 510.41 ± 230.39). Bloodstream was the most frequent isolation site, and most of the strains were isolated from Intensive Care Units. These data demonstrated a potent inhibitory and bactericidal effect of cinnamaldehyde against carbapenem-resistant A.baumannii nosocomial strains, suggesting the prospection of this compound for the development of a new antibacterial substance.