Antimicrobial Activity Methods

Plant extracts are widely utilized for their antimicrobial effect, alone or in combination with traditional drugs. However, the current global lack of harmonization on the assays used to investigate their biological effect makes the result comparison very challenging. In the present chapter, we highlight the variables used for the antimicrobial testing, which may affect the end result. The in vitro antimicrobial methods, including diffusion methods, dilution methods and thin-layer chromatography-bioautography are reported, together with a range of assays aimed at evaluating the mechanisms of action of the extract. Furthermore, in vivo test procedures are evaluated, with a focus on the impact of the differences in the testing animal and the procedure used.