[Determination of colistin based on biothermal activity detection method]

Area of Science:

• Microbiology
• Analytical Chemistry
• Biotechnology

Background:

• Colistin is a critical antibiotic for treating multidrug-resistant Gram-negative bacterial infections.
• Accurate and rapid methods for determining antibiotic potency are essential for effective treatment and infection control.
• Existing methods like the cup-plate assay can be time-consuming.

Purpose of the Study:

• To establish and validate a biothermal activity detection method for determining colistin potency.
• To assess the sensitivity, accuracy, and speed of the biothermal method compared to the standard cup-plate method.
• To explore the potential application of this method for real-time bacterial growth monitoring.

Main Methods:

• Determination of biothermal activity fingerprints of Escherichia coli (E. coli) in the presence of varying colistin concentrations.
• Analysis of the linear relationship between logarithm colistin concentration (lgC) and lag rate of growing time (Deltat%).
• Comparison of results with the conventional cup-plate method.

Main Results:

• A strong linear relationship (r = 0.993) was observed between lgC and Deltat% within a specific colistin concentration range (17.0–41.6 u x mL(-1)).
• The biothermal method demonstrated an average recovery rate of 100.3%.
• No significant difference was found between colistin potency measurements obtained by the biothermal method and the cup-plate method (P > 0.05).

Conclusions:

• The biothermal activity detection method is a sensitive, accurate, rapid, convenient, and feasible approach for determining colistin potency.
• This method shows promise for real-time, online monitoring of bacterial growth processes.
• The biothermal method can serve as a valuable complementary technique to the established cup-plate method.