Test Multidrug resistant Strains used Diameter of the inhibition zone in mm A. indica (x) mm W.somnifera (y) mm Combined Effect (c) mm % increase on the basis of πr2 Ethanolic extract Aqueous Extract Ethanolic extract Aqueous Extract Ethanolic extract Aqueous extract Ethanolic extract (c-x)/x X 100 Aqueous extract (c-y)/y X 100 Ai Ws Ai Ws Ai Ws Ai Ws 1 S.aureus 17 12 21 10 22 24 14 13 67.4 30.6 36.2 69.3 2 E.coli 14 12 12 10 18 15 15 12 65.3 55.9 56.4 44

KEY: Ai: Azadirachta indica, Ws: Withania somnifera. Mean surface area of the inhibition zone (mm2) was calculated as πr2 on the basis of their mean diameter (2r) and % increase was calculated based on the formula shown in the table. The zones of inhibition formed singly with respect to x and y and those formed multiply against the same compound were larger in size with respect to MDR strains.

Table 2: Synergistic interaction study using A. indica and W. somnifera crude extracts on MDR strains.