Mechanisms of the post-antibiotic effects induced by rifampicin and gentamicin in Escherichia coli.
OBJECTIVE
The mechanisms by which antibiotics induce a post-antibiotic effect in susceptible bacteria are poorly understood. To explore the mechanisms more fully we examined the recovery of macromolecular synthesis in Escherichia coli during gentamicin- and rifampicin-induced post-antibiotic effects.


METHODS
E. coli ATCC 25922 was exposed to rifampicin and to gentamicin at 5x MIC for 60 min to induce post-antibiotic effects. The antibiotics were then removed from the culture medium by washing the cells. The rates of DNA, RNA and protein synthesis during the post-antibiotic effect and recovery periods were subsequently determined by measuring the incorporation of radiolabelled uridine, thymidine and leucine into trichloroacetic acid precipitable material.


RESULTS
Recovery of E. coli ATCC 25922 from the rifampicin-induced post-antibiotic effect coincided with the recovery of RNA and protein synthesis. Recovery from the gentamicin-induced post-antibiotic effect coincided with the recovery of protein synthesis.


CONCLUSIONS
These data support the hypothesis that antibiotic molecules retained in the cell mediate the post-antibiotic effect by suppressing the biochemical activity of their molecular targets.
Stubbings
William
W
Antimicrobial Research Centre and Research Institute of Molecular and Cellular Biology, University of Leeds Leeds LS2 9JT, UK.
Bostock
Julieanne
J
Ingham
Eileen
E
Chopra
Ian
I
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000096:biosynthesis; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis; D005839:Gentamicins / Q000494:pharmacology*; D012329:RNA, Bacterial / Q000096:biosynthesis; D012293:Rifampin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D005839:Gentamicins; D012329:RNA, Bacterial; D012293:Rifampin