Antibiotic killing of drug-induced bacteriostatic cells.

There is a long-standing belief that bacteriostatic drugs are inherently antagonistic to the action of bactericidal antibiotics. This belief is primarily because the action of most bactericidal antibiotics requires the target bacteria to be growing. Since bacteriostatic drugs stop the growth of treated bacteria, these drugs would necessarily work against one another. Our results question this long-standing belief by demonstrating conditions where sequential treatment with a bacteriostatic then bactericidal antibiotic is as or more effective than treatment with a bactericidal drug alone. These results raise the need to investigate the pharmacodynamics of the joint action of bacteriostatic and bactericidal antibiotics in vitro and in vivo.