Figure 3: Effect of A Achillea fragrantissima essential oil on the viability of various microorganisms. The bacterial cells were grown broth media incubated with essential oil at 37°C with different time ranged from 0 to 16 hours and the number of viable cells was estimated as previously described Figure 3 (A) Staphylococcus aureus and Figure 3 (B) E. coli.