Susceptibility of Paenibacillus larvae isolates to a tetracycline hydrochloride and Cinnamon (Cinnamomum zeylanicum) essential oil mixture .

GENDE L. B.; FERNANDEZ, NJ; BUFFA F; RUIU L; SATTA A.; FRITZ R.; EGUARAS M. J.; FLORIS I.

BULLETIN OF INSECTOLOGY

ALMA MATER STUDIORUM, UNIV BOLOGNA

Lugar: Bologna; Año: 2010 vol. 63 p. 247 - 250

1721-8861

The antimicrobial activity of tetracycline hydrochloride (OTC) and cinnamon (Cinnamomum zeylanicum Nees) essential oil (CEO)was evaluated against six different isolates of Paenibacillus larvae (White), the causal agent of American Foulbrood (AFB) diseasein honey bee colonies. The bacteria isolates were collected from different localities of Argentine. Minimal inhibitory concentration(MIC) in MYT broth by the tube dilution method was evaluated for each substance and for the combinations of both antimicrobialsusing Krogstad and Moellering technique in order to establish the possible synergistic effects between these substances. OTC meanMIC values were of 3.67 ± 1.80 μg/ml, while the mean MIC values obtained for CEO were of 41.67±19.17 μg/ml. An inhibitorysynergetic effect between these substances was observed with FIC index < 1 on 50% of the on P. larvae isolates.