Name of bacteria Description Average of zone
 inhibition (mm) ±SD
  Degree
of inhibition   
Blue River Ellegance Purple 
Staphylococcus aureus ATCC 25923* 21.8 ± 0.4 24.0 ± 0.2 BR  +++
EP  +++
Staphylococcus aureus  MRSA ** 25.0 ± 0.3 26.0 ± 0.6 +++
+++
Pseudomonas aeruginosa ATCC 9027 10.1 ± 0.2 8.0 ± 0.2 +/-
+/-
Pseudomonas aeruginosa PCR skin *** 8.9 ± 0.5 NZ +/-
-
Escherichia coli   ATCC 25922 12.5 ± 0.3 13.2 ± 0.4 +
+
Enterococcus faecalis   9.0 ± 0.2 10.5 ± 0.3 +/-
+
*The S. aureus strain ATCC 25923 is a strain to control antibiograms,
** MRSA – Methicillin Resistant Staphylococcus aureus is a multi-antibiotic
resistance strain,
*** PCR – Polymerase Chain Reaction ; NZ= No zone inhibition of growth
Relative degree of inhibition of bacterial growth: ≤ 6 mm (-) no zone inhibition of
growth; 7-9 mm (+/-);
10-14 mm (+); 15-18 (++); ≥ 19 mm (+++)
Table 3: Zones of inhibition of bacterial growth by essential oils from the leafy stems of two lavender (Lavandula angustifolia) varieties and relative degree of inhibition of bacterial growth.