Streptomycin and Penicillin Resistant Staphylococci; Influence of pH, Body Fluids on Streptomycin Action

Abstract

Certain organisms of the Smith strain of Staphylococcus aureus possess a natural increased resistance to streptomycin. This resistance is not based on the production of a "streptomycinase." Streptomycin resistance is a relatively permanent characteristic and is not affected by several passages through mice. The resistant organisms retain their virulence for this host. Streptomycin resistance and penicillin resistance are independent of each other. Staphylococci originally penicillin-sensitive retain their sensitivity to penicillin after being made resistant to streptomycin , and vice versa. Treatment with relatively large amts. of streptomycin is ineffective in mice infected with a streptomycin-resistant strain of S. aureus. Penicillin is effective, however. The bacteriostatic effect of streptomycin diminishes as acidity of the culture medium increase from pH 7.7 to 5.2. Streptomycin is not destroyed nor are its bacteriostatic and bactericidal powers affected by serous body fluids, pus, or normal tissue juices.