The present study was aimed to evaluate the in-vitro susceptibility of Aeromonas spp. to ethanolic extracts of propolis (one green and two brown) from three Brazilian states (Minas Gerais, Ceará and Pernambuco). In order to verify the antimicrobial activity of the propolis in vitro, 15 Aeromonas spp. isolates were tested to determine the minimal bactericidal concentration (MBC) of the extracts. Ethanol at 70% was used as a control. Survival curves for the bacterial growth were determined by incubation of the isolates in ethanolic extracts of propolis at 15% for 24 hours. The averages of the MBC of propolis extracts were 1.68% for the green propolis of Minas Gerais, 2.31% for the brown propolis of Ceará, and 3.75% for the brown propolis of Pernambuco. The survival curve of the isolates showed partial inhibition until three hours of incubation. This result is compatible with the bacteriostatic effect of propolis that may be useful to antibiotic therapy in aquaculture, as an alternative to few available antimicrobial drugs.
Aquaculture; A. hydrophila; apiculture; resistance; propolis