[Conditions influencing the activity of fosfomycin in vitro (author's transl)].

The determination of the antibacterial activity of fosfomycin in vitro is most suitably carried out in serial dilution tests on Mueller-Hinton agar. In this, the reproducibility of the minimal inhibitory concentrations (MIC) is the best and is the least dependent on the size of the inoculum. In addition, there is no "skip-tube" effect with this method of determination. The reproducibility of the MIC values increases for several bacterial species on addition of glucose-6-phosphate and at the same time the inhibitory values are lower. If human urine is used as the nutrient medium, the inhibitory values of fosfomycin increase for many species. The action of the antibiotic is not reduced on addition of human blood to the Mueller-Hinton agar.