ABNORMAL PHYSIOLOGICAL-PROPERTIES AND ALTERED CELL-WALL COMPOSITION IN STREPTOCOCCUS-PNEUMONIAE GROWN IN THE PRESENCE OF CLAVULANIC ACID

Subinhibitory concentrations of clavulanate caused premature induction of stationary-phase autolysis, sensitization to lysozyme, and reducti ons in the MICs of deoxycholate and penicillin for Streptococcus pneum oniae. In the range of clavulanate concentrations producing these effe cts, this beta-lactam compound was selectively bound to PBP 3. Cell wa lls isolated from pneumococci grown in the presence of clavulanate sho wed increased sensitivity to the hydrolytic action of purified pneumoc occal autolysin in vitro. High-performance liquid chromatography analy sis of the peptidoglycan isolated from the clavulanate-grown cells sho wed major qualitative and quantitative changes in stem peptide composi tion, the most striking feature of which was the accumulation of pepti de species carrying intact D-alanyl-D-alanine residues at the carboxy termini, The altered biological and biochemical properties of the clav ulanate-grown pneumococci appear to be the consequences of suppressed D,D-carboxypeptidase activity.