Abstract: An incubation limit marker for revealing the growth of contaminants present in a sample includes at least one strain or category of classically contaminant bacteria in dehydrated form which, once regenerated, will be present at a maximum concentration of 10.sup.3 CFU/ml. The incubation limit marker also includes a medium used for the dehydration of the contaminant bacterium or bacteria which includes a substrate capable of being degraded by the bacterium or bacteria. The incubation limit marker further includes an indicator of the growth of the bacterium or bacteria, for example, constituted by a colored indicator of changes in pH. A process for the "in vitro" detection of the susceptibility of pathogenic bacteria to various antibiotics present in MIC (i.e., Minimal Inhibitory Concentration) in culture or antibiogram media is carried out directly from the sample of the infected medium, in the presence of the above marker, used as a signal which limits the reading time of the antibiogram.

Abstract: This process is essentially characterized by enzymatic reactions which are carried out under anaerobic conditions between a liquid growth medium for mycoplasms containing a dilution medium of the sample of fluid to be analyzed and, on the one hand, a first substrate comprising dehydrated urea or glucose in the presence of a color pH indicator also in dehydrated form and, on the other hand, a second substrate comprising arginine also in dehydrated form or glucose in the presence of a color pH indicator and that the speed of the enzymatic response is followed while noting the time corresponding to the color change of the indicators, the respective quantities of urea and arginine or of glucose, on the one hand, and the concentration and the nutrient composition of the said growth and dilution medium, on the other hand, being first selected and standardized in such a way that for Ureaplasma urealyticum present at a supra or sub-pathological rate, the color change of the indicator is or is not obtained after a giv