C albicans

The minimum inhibitory concentration (MIC) and the minimum biocidal concentration (MBC) were determined by serial twofold dilutions. Test strains used in the study were S. aureus, E. coli, P. aeruginosa, and C. albicans from MicroBioLogics, Inc. (St. Cloud, USA). The MIC of the preparations was determined on liquid media: Mueller-Hinton broth (Merck, Germany) for bacteria and Sabouraud broth (BTL, Poland) for C. albicans. 0.1 ml of inoculum (24-h strains of 0.5 McFarland density) was introduced into prepared tubes with the medium and tested preparation. The control was a tube of Mueller-Hinton broth (10 ml) without any preparation (blank test). Samples were incubated at 37 °C for 24 h (bacteria) and 72 h (yeast fungi). The MIC value was taken as the concentration of the preparation that completely inhibited the growth of microorganisms (no turbidity in the tube). In order to determine the MBC from cultures of bacteria and fungi considered negative, cultures were performed on solid Triptic Soy Agar and Sabouraud medium (BTL, Poland). After 24 h and 72 h (bacteria and fungi) of incubation at 37 °C, a culture determination (macroscopic evaluation) was performed. MBC was defined as the lowest concentration of the formulation resulting in complete inhibition of bacterial/fungal growth.