Growth of staphylococci on mercuric chloride agar.

Smith, P. B. (Communicable Disease Center, Atlanta, Ga.). Growth of staphylococci on mercuric chloride agar. J. Bacteriol. 84:1016-1019. 1962.-An attempt has been made to corroborate a report that "epidemic" strains of staphylococci are more resistant to mercuric salts than are "nonepidemic" strains. A comparison of mercury resistance with coagulase production and phage type or pattern of 493 staphylococcal strains revealed that nearly half of the coagulase-negative strains tested were mercury-resistant, whereas many "epidemic" strains of certain phage types were sensitive to mercuric salts. Results obtained are compared with those from a previous investigation. The mercury resistance of some strains was found to vary significantly depending on the basal medium used; this could not be correlated with mercapto-group content of the medium. The data indicate that a medium containing mercuric chloride would have little practical value at the present time for the average laboratory engaged in isolating staphylococci.