Antimicrobial Effect of Butylated Hydroxyanisole and Butylated Hydroxytoluene on Staphylococcus aureus ¹

The antimicrobial effect of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on three enterotoxigenic strains of Staphylococcus aureus in Brain Heart Infusion broth (BHI) was evaluated by turbidity measurements. Also, the interaction of these compounds with pH and NaCl on growth of S. aureus strain 100 was measured. Inhibition of S. aureus growth increased with an increase in the concentration of BHA and/or BHT. Complete inhibition of S. aureus growth occurred in BHI with 1.12 μmole of BHA/ml or 0.70 μmole of BHT/ml as well as with a combination of 0.25 μmole of both BHT and BHA/ml. Inhibition of S. aureus growth by BHA or BHT was substantial at pH 7.0 and with 2% NaCl. When 0.84 μmole or greater of BHA/ml and 0.47 μmole or greater of BHT/ml were added to BHL, growth of S. aureus 100 was inhibited to the extent that enterotoxin A could not be detected after 24 h of incubation.