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.
Keywords: Antimicrobial methods, Plant extracts, In vitro testing, Diffusion methods, Dilution methods, Bioautography, In vivo antimicrobial assays, Synergy testing.
