INHIBITION OF BACTERIAL ESTERASES BY CHLORAMPHENICOL (CHLOROMYCETIN)

Abstract

Studies on the mode of action of chloramphenicol at therapeutic levels indicate that the ability of this new antibiotic to inhibit the normal metabolic processes of pathogenic bacteria may be related to its inhibitory action of esterases. Results with bacterial and crystalline liver esterase show excellent anti-esterase action while with mitochondria and intact animal cells the anti-esterase action is incomplete. This suggests that some barrier exists at the cell wall and at the mitochondria which prevents the chloramphenicol from reacting with the esterase within the animal cell and the esterase activity of the mitochondria. Four distinct responses have been observed at various concn. levels of chloramphenicol on the growth and esterase activity of Escherichia coli cells. At extremely low concns., the drug produces no significant change in either growth or esterase activity. With slightly higher concns. a slight inhibitory effect is observed. This in turn is followed by a marked activation of both processes. In the 4th concn. range, which is the therapeutic range, there is a marked inhibition of both growth and esterase activity. This inhibiting action of chloramphenicol on esterase may therefore be a clue to the bacteriostatic action of this antibiotic.