[Experimental studies to culture bacteria from blood specimen with an addition of ampicillin in various nutrient media (author's transl)].

Ampicillin-sensitive or -resistant Staphylococcus aureus and Klebsiella strains were cultured in various nutrient media as prototypes of the agents of sepsis isolated in bacteriological routine analysis. In each case, 2 ml of defibrinated human blood containing 100 and 1000 cells, 8 gamma and 80 gamma ampicillin/1 ml blood respectively were added to 50 ml of nutrient medium. The following media were used. 1. casein soya-bean meal peptone broth (Oxoid), 2. tryptose-phosphate medium (Oxoid), 3. dextrose broth (Oxoid), 4. brain-heart-dextrose medium (Oxoid), 5. brain-heart infusion, autoclaved (Difco), 6. brain-heart infusion, after sterile filtration (Difco), 7. vacutainer culture bottles (BD) prepared medium, 8. micrognost blood culture bottles (Biotest) prepared medium. While the sensitive staphylococcus strain exhibited a slower growth than the sensitive Klebsiella strain in all nutrient media, the growth rate of the two resistant variants was approximately the same for an initial count of 100 cells per ml of blood. Among the resistant staphylococci the higher initial count of the inoculum resulted in an improved growth. After addition of 8 gamma or 80 gamma ampicillin/1 ml blood the sensitive staphylococcus strain did not show any grwoth irrespective of the inoculated number of cells while the sensitive Klebsiella strain multiplied irrespective of the initial number of cells. After 24 hours the resistant staphylococci and Klebsiella strains of which 1000 cells each had been used for inoculation exhibited growth in almost all media used.