Modelling the effect of combined antimicrobials: A base model for multiple-hurdles

Area of Science:

• Food microbiology
• Antimicrobial resistance
• Predictive modeling

Background:

• Combined antimicrobial treatments are crucial for food safety and combating antimicrobial resistance.
• Current microbiological predictive models often rely on Bliss Independence or Loewe reference models (LRM).
• Existing models face challenges in accurately predicting the efficacy of antimicrobial mixtures.

Purpose of the Study:

• To evaluate the applicability of Bliss Independence and LRM for analyzing combined antimicrobial effects in food.
• To develop and validate a new model for predicting antimicrobial mixture efficacy.
• To investigate the combined effects of NaCl and KCl on bacterial growth.

Main Methods:

• Growth analysis of Aeromonas hydrophila, Cronobacter sakazakii, and Escherichia coli using optical density.
• Comparison of Bliss Independence and LRM with experimental data from NaCl/NaCl and NaCl/KCl mixtures.
• Development and application of a modified LRM accommodating varied concentration exponents.

Main Results:

• Bliss Independence models showed inconsistencies when applied to combined antimicrobials in food.
• The standard LRM was found to be valid only under specific conditions of identical concentration exponents.
• A new modified LRM accurately predicted the additive effects in the NaCl/KCl mixture.

Conclusions:

• Existing models for combined antimicrobial effects in food require revision.
• A modified Loewe reference model, allowing for mixed exponents, provides a more robust framework.
• Accurate modeling of antimicrobial mixtures is essential for effective food safety strategies.