Cycloserine Induction, Propagation, and Antimicrobial Susceptibility of Wall-Defective Staphylococcus aureus.

A method of induction of L colonies of Staphylococcus aureus by cycloserine, the propagation of wall-defective staphylococci (WDS), and the development and antimicrobial susceptibility of stable WDS are presented. The growth and morphology of the cycloserine-induced L colonies and WDS were indistinguishable from those induced by methicillin or lysostaphin. The antimicrobial susceptibility of the stable cycloserine-induced WDS was similar to that of the stable methicillin-induced and lysostaphin-induced WDS by both broth dilution and agar diffusion techniques. A survey of the English literature reveals that wall-defective bacteria are always resistent to antimicrobial agents which inhibit cell wall synthesis (cycloserine, penicillins, and cephalosporins). They are virtually all susceptible to antimicrobial agents which have other modes of action. The susceptibility to vancomycin and bacitracin varied from study to study.