Abstract
Summary
It has been shown that S. aureus grown in the presence of subinhibitory concentrations of nafcillin produced a disturbance or disorganization of the cell wall fabric resulting in a marked accumulation of a polysaccharide within the cell. An appreciable polysaccharide response was also found for oxacillin, methicillin and erythromycin. This conclusion is based on data which demonstrate a clear differentiation between such an inhibitor of bacterial wall synthesis as penicillin which exerted a pronounced effect on polysaccharide synthesis and other antibacterial antibiotics which failed to increase the quantity of polysaccharide formed. In addition, treatment with nafcillin rendered the normally lysozyme resistant cells of S. aureus susceptible to partial lysis by lysozyme and the concomitant addition of trypsin resulted in further dissolution of the cell bodies. Electron micrographs of such treated cells subjected to thermal stress provide further evidence of the relationship between accumulation of polysaccharide and actual interference with cell wall synthesis. The significance of the results relating to the mechanism of action of the semi-synthetic penicillin nafcillin and possibly other penicillins is discussed.
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