Abstract Objectives: The main goal of the provided experiments was to test the influence of the used in the Disc Diffusion Method (DDM) Mueller Hinton agar (MHA) and to establish its reflection on the interpretation of the antimicrobial test.
Methods: This study is based on developed microbiological methodology and outworked protocol for qualification of the Mueller Hinton agar when it is used in Disc Diffusion Method in order to obtain reliable and reproducible results on quality indicators for MHA, appointed by the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST).
Results: Conducted studies showed the influence of the used medium MHA or MHA II on the zones of inhibition of antimicrobial discs in DDM, which can impact the interpretation of antibiotic susceptibility of isolates. This kind of testing of the medium MHA gives also the opportunity to establish some deviations in the activity of the antimicrobials used in the production of antimicrobial discs. In serial experiments was encountered a problem with the activity of Gentamicin substance that affects the quality of produced batches antimicrobial discs with him.
Conclusions: The experiments established the influence of the used medium MHA or MHA II on the zones of inhibition of antimicrobial discs in DDM. The used protocol with microbiological testing was very helpful as for evaluation of the MHA and for establishment of antimicrobials activity deviations.
Keywords Mueller Hinton agar, Disc Diffusion Method, zones of inhibition, antimicrobial discs, Gentamicin.