The effect of 20-hydroxyecdysone on the susceptibility of Escherichia coli to different antibiotics.
OBJECTIVE
The aim of this study was to investigate the influence of 20-hydroxyecdysone (20E) on the susceptibility of growing Escherichia coli to antibiotics.


RESULTS
Susceptibility of E. coli to antibiotics in the presence of 20E was estimated by determination of the colony-forming ability and the specific growth rate. Pretreatment with 20E decreased the bactericidal effect of ciprofloxacin (0·3 and 3·0 μg ml-1), streptomycin (10 and 40 μg ml-1) and kanamycin (10 μg ml-1) and increased the bactericidal action of 0·03 μg ml-1ciprofloxacin. To study the influence of 20E on gene expression, we used strains of E. coli carrying fusions of promoters of relevant genes with the structural gene of β-galactosidase. 20E had no marked effect on the expression of antioxidant genes katG, katE, sodA and the rpoS gene (general stress response), while it (alone or combined with ciprofloxacin) markedly stimulated expression of the sulA gene belonging to the SOS regulon (DNA damage response).


CONCLUSIONS
In growing E. coli, 20E modulated the bactericidal action of antibiotics and stimulated the SOS response.


CONCLUSIONS
The results of this study may be used to enhance the efficiency of antibacterial therapies.
Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Perm, Russia.
G
G
Smirnova
Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Perm, Russia.
K
K
Bezmaternykh
Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Perm, Russia.|Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, Perm, Russia.
O N
ON
Oktyabrsky
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D004347:Drug Interactions; D004441:Ecdysterone / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D007612:Kanamycin / Q000494:pharmacology; D013014:SOS Response, Genetics / Q000187:drug effects
D000900:Anti-Bacterial Agents; D004441:Ecdysterone; D007612:Kanamycin; D002939:Ciprofloxacin

Escherichia coli
; 20-hydroxyecdysone; SOS response; antibiotics; gene expression; susceptibility