Acta Vet. Brno 2014, 83: 9-12

Testing of inhibition activity of essential oils against Paenibacillus larvae – the causative agent of American foulbrood

Katarína Kuzyšinová1, Dagmar Mudroňová2, Juraj Toporčák1, Radomíra Nemcová2, Ladislav Molnár1, Aladár Maďari3, Slavomíra Vaníková4, Martin Kožár5

1University of Veterinary Medicine and Pharmacy, Clinic of Birds and Exotic Animals, Košice, Slovak Republic
2University of Veterinary Medicine and Pharmacy, Department of Microbiology and Immunology, Košice, Slovak Republic
3University of Veterinary Medicine and Pharmacy, Clinic of Small Animals, Košice, Slovak Republic
4Slovak Academy of Sciences, Institute of Animal Physiology, Košice, Slovak Republic
5Clinic of Small Animals, Košice, Slovak Republic

American foulbrood is a dangerous world-wide spread disease of honey bees caused by the Paenibacillus larvae bacterium. Antibiotic treatments are less effective and leave residues in bee products. It is therefore necessary to find an alternative, especially using natural ingredients such as plant essential oils, probiotics, fatty or organic acids. Two strains of P. larvae were used for this study: CCM 4488, a strain from the Czech collection of micro-organisms and a Slovak field strain which was isolated from infected bee combs and characterized on the basis of biochemical properties. Plant essential oils of sage (Salvia officinalis), anise (Pimpinella anisum), oregano (Origanum vulgare), caraway (Carum carvi), thyme (Thymus vulgaris), rosemary (Rosmarinum officinalis), clove (Syzygium aromaticum), camomile (Chamomilla recutita) and fennel (Foeniculum vulgare) were used for the testing of the inhibitory activity against P. larvae. Essential oils at amounts of 5 µl and 10 µl were applied to sterile discs on MYPGP agar; inhibition zone diameters were measured after 24-h incubation at 37 °C. The strongest inhibitory activity against both P. larvae strains was noted in case of the essential oils from oregano, thyme and clove; essential oils from camomile, rosemary and fennel showed no or weak antibacterial activity. Medium strong inhibition activity was recorded in case of previously untested essential oil from Carum carvi. There was a difference in sensitivity of both tested strains to essential oils. Our study confirmed that some essential oils can be used in the prevention of American foulbrood but further experiments aimed at their influence on physiological intestinal microflora of honey bees must be performed.


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