The modulation of the bacteriolytic effect of beta-lactam antibiotics by non-antibiotics.

The addition of cationic proteins such as lysozyme, ribonuclease and cytochrome C enhanced the beta-lactam-induced bacteriolysis of staphylococci measured as release of wall label or by optical density. The treatment of staphylococci with penicillin plus cytochrome C resulted in a reduced viability of bacteria compared with those treated with penicillin alone. The wall autolysis and the penicillin-induced bacteriolysis of staphylococci were enhanced by the lysosomal enzyme cathepsin C. The penicillin-induced bacteriolysis was also enhanced by the D-amino acids D-alanine and D-methionine, while the comparable L-amino acids did not reveal any activity. On the other hand, some polyanionic substances were able to suppress the penicillin-induced bacteriolysis. Radiochemical and electron microscopic studies revealed the participation of bacterial wall autolysins in the first steps of degradation processes of staphylococcal walls within murine bone marrow-derived macrophages.