Published in Scientific Works. Series C. Veterinary Medicine, Vol. LXIII, Issue 2
Written by Valentin NICORESCU, Gabriela CIOBANU, Maria CRIVINEANU, Camelia PAPUC, Corina PREDESCU
One of the major risks resulting from the consumption of honey is the presence of drug residues, especially antibiotics, because they are widely used for treating various diseases. The study aimed to evaluate antibiotic residues in honey, in terms of quality and quantity, by diffusimetric methods. Thus, the studied antibiotics were oxytetracycline and streptomycin, and their action was studied using three bacterial strains, namely Bacillus subtilis, Staphylococcus aureus ATCC 6538 and Staphylococcus aureus ATCC 25923. S. aureus ATCC 25923 and S. aureus ATCC 6538 strains proved to be very sensitive to oxytetracycline and streptomycin. Bacillus subtilis showed no zone of inhibition for the 4 concentrations of oxytetracycline and for all 7 concentrations of streptomycin, indicating the high degree of resistance of the bacteria to these antibiotics. The analysis of honey samples contaminated with oxytetracycline and streptomycin showed inhibition zones with radius segments that were not strictly directly proportional to the antibiotic’s concentration. In this respect, the tests carried out revealed the presence of inhibition zones even around the negative control. Both as such and diluted, honey caused the inhibition of bacterial growth, inhibition zones being directly proportional to the percentage of honey. In view of the fact that the honey itself possesses antibacterial properties, testing of honey samples in order to identify antibiotic residues cannot be achieved by microbiological methods, since there is a risk of obtaining false-positive reactions.
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