Rapid Antibiotic Susceptibility Testing via Electrochemical Measurement of Ferricyanide Reduction by Escherichia coli and Clostridium sporogenes
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- 作者：Peter Ertl ; Elizabeth Robello ; Fernando Battaglini ; and Susan R. Mikkelsen
- 刊名：Analytical Chemistry
- 出版年：2000
- 出版时间：October 15, 2000
- 年：2000
- 卷：72
- 期：20
- 页码：4957 - 4964
- 全文大小：89K
- 年卷期：v.72,no.20(October 15, 2000)
- ISSN：1520-6882
文摘
Electrochemical measurement of respiratory chain activityallows rapid and reliable screening for antibiotic susceptibility in microorganisms. Chronoamperometry and chronocoulometry of suspensions of aerobically cultivated E.coli combined with the non-native oxidant potassiumhexacyanoferrate(III) (ferricyanide) yield signals for reoxidation of the reduction product ferrocyanide that aremuch smaller if the E. coli has been incubated briefly withan effective antibiotic compound. Chronocoulometricresults, obtained following 20-min incubation with antibiotic and 2-min measurement in assay buffer containing50 mM ferricyanide and 10 mM succinate, at +0.50 Vvs Ag/AgCl at a Pt working electrode, were compared withtraditional disk diffusion susceptibility testing, whichrequires overnight incubation on agar plates; the resultsshow significantly lower accumulation of ferrocyanide inall cases in which growth inhibition was observed in thedisk diffusion assay. A range of antibiotic compounds (13)were examined that possess different mechanisms ofaction. Quantitative determination of IC50 values forpenicillin G and chloramphenicol yielded values that were100-fold higher than those obtained by standard turbiditymethods after 10-h incubation; this is likely a result ofthe very brief (10 min) exposure time to the antibiotics.Addition of 5 
M 2,6-dichlorophenolindophenol, a hydrophobic electron-transfer mediator, to the assay mixtureallowed susceptibility testing of a Gram-positive obligateanaerobe, Clostridium sporogenes. This rapid new assaywill facilitate clinical susceptibility testing, allowing appropriate treatment virtually as soon as a clinical isolatecan be obtained.
M 2,6-dichlorophenolindophenol, a hydrophobic electron-transfer mediator, to the assay mixtureallowed susceptibility testing of a Gram-positive obligateanaerobe, Clostridium sporogenes. This rapid new assaywill facilitate clinical susceptibility testing, allowing appropriate treatment virtually as soon as a clinical isolatecan be obtained.