The slow bactericidal effect of tetracycline and minocycline on wall-defective staphylococcus.

Tetracycline, considered to be a bacteriostatic antibiotic, has slow bactericidal activity against Staphylococcus aureus in vitro [1]. The concentration of tetracycline required to inhibit the growth of stable, cell wall-defective S. aureus (WDS) in vitro is lower than that required to inhibit the parent strain of S. aureus [2]. The experiments presented here were designed to determine if the rate of killing of WDS by tetracycline and its derivatives was slow or rapid. The two antibiotics selected for study were tetracycline and its analog, minocycline, which is more effective in vitro against S. aureus [3].