Antibacterial Effects of Dimethyl Sulfoxide
The minimal inhibitory concentration (MIC) of dimethyl sulfoxide to the nearest 10% in nutrient broth was determined for two isolates each of Staphylococcus aureus, S aureus variety albus, β -hemolytic streptococci, Corynebacterium acnes, Corynebacterium species (normal skin residents), Alcaligenes faecalis, Escherichia coli, and Proteus species. Twenty percent dimethyl sufoxide was found to be bacteriostatic to all of these. The bactericidal concentrations were established by subculturing after 24 hours. For S aureus, the bactericidal concentration (50%) was 2.5 times that of the MIC; for the remainder, it ranged from 30% to 40%, with the gram-negative bacteria being somewhat more susceptible.Dimethyl sulfoxide, by modern standards, is only weakly antibacterial. It is roughly comparable to many other solvents and far inferior to alcohol. The concentration required to kill all of the above organisms after one-hour exposures to aqueous solutions of dimethyl sulfoxide ranged from 65% to 75%.