Related Experiment Video
Updated: Dec 16, 2025
Metabolic Profiling to Determine Bactericidal or Bacteriostatic Effects of New Natural Products using Isothermal Microcalorimetry
Published on: October 29, 2020
Minimum Bactericidal Concentration of Ciprofloxacin to Pseudomonas aeruginosa Determined Rapidly Based on Pyocyanin
Yi Liu1, John H Moore1, Glynis L Kolling2
1Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904, USA.
Abstract:
Infections due to Pseudomonas aeruginosa (P. aeruginosa) often exhibit broad-spectrum resistance and persistence to common antibiotics. Persistence is especially problematic with immune-compromised subjects who are unable to eliminate the inhibited bacteria. Hence, antibiotics must be used at the appropriate minimum bactericidal concentration (MBC) rather than at minimum inhibitory concentration (MIC) levels. However, MBC determination by conventional methods requires a 24 h culture step in the antibiotic media to confirm inhibition, followed by a 24 h sub-culture step in antibiotic-free media to confirm the lack of bacterial growth. We show that electrochemical detection of pyocyanin (PYO), which is a redox-active bacterial metabolite secreted by P. aeruginosa, can be used to rapidly assess the critical ciprofloxacin level required for bactericidal deactivation of P. aeruginosa within just 2 hours in antibiotic-treated growth media. The detection sensitivity for PYO can be enhanced by using nanoporous gold that is modified with a self-assembled monolayer to lower interference from oxygen reduction, while maintaining a low charge transfer resistance level and preventing electrode fouling within biological sample matrices. In this manner, bactericidal efficacy of ciprofloxacin towards P. aeruginosa at the MBC level and bacterial persistence at the MIC level can be determined rapidly, as validated at later timepoints using bacterial subculture in antibiotic-free media.
Insights
Rapidly determine antibiotic effectiveness against Pseudomonas aeruginosa using electrochemical pyocyanin detection. This method quickly distinguishes bactericidal from inhibitory antibiotic concentrations, improving treatment for persistent infections.
Area of Science:
- Clinical Microbiology
- Electrochemical Biosensing
- Antimicrobial Resistance
Background:
- Pseudomonas aeruginosa infections are challenging due to antibiotic resistance and bacterial persistence.
- Effective treatment requires using antibiotics at minimum bactericidal concentration (MBC) rather than minimum inhibitory concentration (MIC).
- Conventional MBC determination is time-consuming, involving multiple culture steps.
Purpose of the Study:
- To develop a rapid method for assessing the bactericidal efficacy of antibiotics against P. aeruginosa.
- To determine the critical antibiotic concentration needed for bacterial deactivation.
- To differentiate between bactericidal and persistent bacterial states.
Main Methods:
- Electrochemical detection of pyocyanin (PYO), a P. aeruginosa metabolite.
- Utilized nanoporous gold electrodes modified with self-assembled monolayers for enhanced sensitivity and reduced interference.
- Assessed ciprofloxacin efficacy within 2 hours in treated growth media.
Main Results:
- Successfully correlated electrochemical PYO detection with bactericidal activity of ciprofloxacin.
- Demonstrated rapid determination of MBC and MIC levels for P. aeruginosa.
- Validated electrochemical results against conventional subculture methods.
Conclusions:
- Electrochemical PYO detection offers a rapid and sensitive method for evaluating antibiotic bactericidal efficacy against P. aeruginosa.
- This approach can accelerate the determination of appropriate antibiotic dosing to combat persistent infections.
- The developed biosensor minimizes interference and electrode fouling, suitable for biological samples.
