Relationship between Lytic and Inhibitory Concentrations of Cephalosporins
The β-lactam antibiotics owe their bactericidal activity to their lytic action on the bacterial cell wall. This property sets them apart from other bactericidal antibiotics, such as the amino-glycosides. Shortly after the introduction of benzylpenicillin some 30 years ago much attention was paid to the lysis phenomenon, especially in relation to the “zone effect” (Eagle & Musselman 1948). However, interest in this aspect waned. The recent increase in the number of semisynthetic β-lactam antibiotics has caused a renewed interest in lytic activity, which has been lead by O’Grady and his colleagues (e.g. Greenwood & O’Grady 1973, 1975). An intriguing finding by these workers is that cephalexin is “lytic-deficient”, in that filamentation rather than lysis is the bacterial response over a wide range of antibiotic concentrations (Greenwood & O’Grady 1973). As cephalexin was unique among the 3-lactam compounds which they tested, in that it has a β-methyl sidechain, it seemed possible that there was some simple relationship between chemical structure and lytic ability among cephalosporins. The present study was designed to investigate this possibility.
KeywordsAcetoxy Methyl Lactam Antibiotic Methyl Methyl Bactericidal Antibiotic Serial Dilution Technique
Unable to display preview. Download preview PDF.