Use and Abuse of Staphylococcus aureus as a Test Organism

The Antagonism of the Antibacterial Action of Mercury Compounds: Part II. Factors Affecting the Action of Mercuric Chloride

Increase in the peptone concentration of the medium causes an increase in the amount of mercuric chloride necessary for bacteriostasis whilst an increase in the sodium chloride content decreases it. The age of the organisms is a factor likely to produce variability in the results and the use of a stored suspension of organisms is suitable for reducing this. Suspensions prepared from plate cultures are less satisfactory than those from slope cultures. The number of viable cells in inocula affects the bacteriostatic concentration of mercuric chloride, an increased concentration of bacteriostat being required with an increased number of organisms. The addition of heat-killed cells appears to make no appreciable difference to the bacteriostatic activity of mercuric chloride.