agar and Sprains-and-Strains

Six coagulase-positive strains of Staphylococcus aureus which had been cultivated in Brain Heart Infusion broth, milk, and brine were plated on seven isolation media. A significant difference in the growth patterns of the individual strains was found as well as a significant effect resulting from the previous cultivation history before plating. Brine and, to a lesser extent, milk were found to reduce maximal cell concentrations attained, but strains grown in brine and milk showed greater ability to withstand the selective action of the isolation media. Fibrinogen applied to the surface of five of the media allowed the formation of characteristic halos by coagulase-positive strains of S. aureus. Only half of the strains studied produced a zone of precipitation on SM110-Egg Yolk agar. The isolation medium containing cycloheximide and a high level of polymxin B was most inhibitory to the organisms.

Topics: Agar; Animals; Coagulants; Coagulase; Culture Media; Dairy Products; Egg Yolk; Fibrinogen; Hemostatics; Hydrolases; Milk; Research; Sprains and Strains; Staphylococcus; Staphylococcus aureus

Cetin, E. T. (Istanbul University, Istanbul, Turkey). Hemolysin-inhibiting substance in Staphylococcus aureus strains. J. Bacteriol. 86:407-413. 1963.-Of 144 Staphylococcus aureus strains isolated from pathological specimens, 3.4% did not cause hemolysis on sheep blood agar; the remainder produced hemolytic and semihemolytic zones, most of which were surrounded by a dense red band. Most of the strains causing pronounced hemolysis and a large dense red band on sheep blood agar also produced a dense red band on human blood agar after incubation at 37 C for about 1 week. In the dense red band on human blood agar, circles of hemolysis were observed when petri dishes were kept at room temperature for approximately 1 more week. The dense red band inhibited delta hemolysis of some of the S. aureus strains growing nearby. Certain strains failing to produce the dense red band on human blood agar inhibited delta hemolysis of other strains grown near them. A hemolysis-inhibiting substance (HIS) was produced in broth and agar media, and could be extracted from agar cultures. HIS was stable for 1 hr at 56 C and for 15 min at 100 C. It lost 75% of its effect when heated for 30 min at 100 C and became ineffective when heated at the same temperature for 45 min. Conditioned hemolysis occurred when some saprophytic gram-positive bacteria grew near or within the dense red band. These organisms also produced conditioned hemolysis without the presence of a visible dense red band, when growing near the strains inhibiting delta hemolysis. When such strains were grown on human blood agar, a conditioned hemolysis also occurred after the border of the medium was flamed.

Topics: Agar; Animals; Cell Death; Culture Media; Hemolysin Proteins; Hemolysis; Hot Temperature; Humans; Research; Sheep; Sprains and Strains; Staphylococcal Infections; Staphylococcus; Staphylococcus aureus

Topics: Agar; Carbon Dioxide; Culture Media; Sprains and Strains; Streptococcus; Streptococcus bovis