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 Original Articles |
| Effects of Salicylates on the Susecptibility of Escherichia coli to Quionolones |
| Phil Youl Ryu, Young Chull Yang, Tai Hew Ahn |
| Department of Microbiology, Chonnam University Medical School, Kwangju, Korea |
Vol.27 Num.5 (p451~459)
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Background : It has been known that sodium salicylate (Sal) and acetylsalicylate (AcSal or aspirin) increase the phenotypic resistance of Escherichia coli against ampicillin, chloramphenicol, cephalosporin, and tetracycline. In this study we determined the resistance-increasing effect and possible mechanism of salicylates on quinolones; nalidixic acid (NA), oxolinic acid, pipemidic acid, ciprofloxacin (CPFX), norfloxacin, and pefloxacin.
Methods : In vitro susceptibility test of E. coli to quinonoles was measured by efficiency of plating (EOP) and minimal inhibitory concentration ((MIC) and minimal bactericidal concentration (MBC) by broth dilution method. To determine whether these effects are caused by a decreased uptake of the antibiotics, the permeation of CPFX or NA through the outer membrane and the change of outer membrane protein production in E. coli were measured.
Results : Sal and AcSal enhanced the resistance of E. coli against quinolones most efficiently at the concentration of 1.25 to 20 mM and 2.5 to 5 mM, respectively. The EOP was increased 10-1000 times on Mueller-Hinton agar containing 5 mM, of Sal or 2.5 mM of AcSal. Compared with in salicylate-free medium, 2 to 8 fold increase in MIC and MBC were observed in salicylates containing medium. When E. coli was cultured in media containing 5 mM of Sal, the permeability of NA and CPFX into E. coli was reduced to about one half. OmpF(36 Kdal protein) of the outer membrane protein of E. coli cultured in 5 mM Sal-containing medium was markedly reduced when observed in SDS-PAGE.
Conclusion : These data suggest that salicylates reduced the production of OmpF, outer membrane protein of E. coli, thereby decreased the membrane permeability, leading to the increase of resistance to quinolones. |
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