Comparison of fluorescence optical respirometry and microbroth dilution methods for testing antimicrobial compounds

Area of Science:

• Analytical Chemistry
• Microbiology
• Biophysics

Background:

• Traditional antimicrobial susceptibility testing methods are time-consuming.
• There is a need for faster, more sensitive methods to evaluate antimicrobial efficacy.

Purpose of the Study:

• To evaluate fluorescence optical respirometry as a method for studying antimicrobials.
• To assess its ability to analyze microbial growth kinetics and determine minimum inhibitory concentration (MIC) values.

Main Methods:

• Synthesis of an oxygen-sensitive ruthenium-tris(4,7-diphenyl-1,10-phenanthroline) dichloride (Ru(DPP)3Cl2) sensor.
• Development of a prototype optical respirometry measurement system.
• Testing the impact of various antimicrobials (ampicillin, co-trimoxazole, nystatin) on bacterial and fungal cultures.

Main Results:

• Fluorescence optical respirometry accurately analyzes microbial growth kinetics and cell growth parameters.
• MIC values obtained are consistent with traditional serial dilution methods.
• The method significantly reduces result turnaround time (5-7 hours for bacteria, 24 hours for yeasts) and sample volume (down to 50 μl).
• It allows monitoring of sub-MIC concentration effects on metabolic activity.

Conclusions:

• Fluorescence optical respirometry is a rapid and sensitive technique for evaluating antimicrobial activity.
• This method offers significant advantages over traditional techniques in terms of speed and sample volume.
• It provides real-time measurement of microbial metabolic activity in response to chemical compounds.