Gelose was the culture medium, and the incubation was performed at 370C, for 16-18 hours; the bacterial cultures were used both for variants and control seeding (DMSO - dimethyl sulfoxide - as solvent for volatile oils); the results were established by measuring the inhibition area diameter (mm), for 2-3 times in different directions, using a marked rule. Result expression consisted of direct transcription of inhibition area diameter in categories of sensitive, resistant or intermediary strains.