Previous Article | Next Article ![]()
Antimicrobial Agents and Chemotherapy, Jul 1995, 1530-1537, Vol 39, No. 7
ME Fichera, MK Bhopale and DS Roos
In order to characterize the delayed effect of clindamycin and macrolide
antibiotics against Toxoplasma gondii tachyzoites (E. R. Pfefferkorn and S.
E. Borotz, Antimicrob. Agents Chemother. 38:31-37, 1994), we have carefully
examined the replication of parasites as a function of time after drug
addition. Intracellular tachyzoites treated with up to 20 microM
clindamycin (> 1,000 times the 50% inhibitory concentration) exhibit
doubling times indistinguishable from those of controls (approximately 7
h). Drug-treated parasites emerge from infected cells and establish
parasitophorous vacuoles inside new host cells as efficiently as untreated
controls, but replication within the second vacuole is dramatically slowed.
Growth inhibition in the second vacuole does not require continued presence
of drug, but it is dependent solely on the concentration and duration of
drug treatment in the first (previous) vacuole. The susceptibility of
intracellular parasites to nanomolar concentrations of clindamycin
contrasts with that of extracellular tachyzoites, which are completely
resistant to treatment, even through several cycles of subsequent
intracellular replication. This peculiar phenotype, in which drug effects
are observed only in the second infectious cycle, also characterizes
azithromycin and chloramphenicol treatment, but not treatment with
cycloheximide, tetracycline, or anisomycin. These findings provide new
insights into the mode of clindamycin and macrolide action against T.
gondii, although the relevant target for their action remains unknown.
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
In vitro assays elucidate peculiar kinetics of clindamycin action against Toxoplasma gondii
Department of Biology, University of Pennsylvania, Philadelphia 19104- 6018, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»