Abstract
The inhibition of S. aureus by fatty acids was pH dependent. The inhibitory properties of myristic acid were greater at pH 5.5 than at pH 7; those of linoleic acid [a human skin lipid constituent] were less at pH 5.5 than at pH 7. Seven clinical penicillin-resistant cultures survived better in the presence of linoleic acid at pH 5.5 than did their sensitive counterparts. The resistance to linoleic acid in most plasmid-carrying cultures at pH 5.5 was probably not due to the production of penicillinase but to some other determinants carried by the plasmid.