Methods Explanation
Disclaimer: this application is for educational and scientific use only. It should not be used for medical diagnosis or therapeutic decisions.
Please read:
The Fractional Inhibitory Concentration (FIC) Index is a tool used to evaluate the interaction between two antibiotics.
A lower FIC value suggests stronger synergy, while a higher value indicates antagonism.
Formula:
Interpretation:
- FIC ≤ 0.5: strong synergy, meaning the antibiotics work significantly better together.
- 0.5 < FIC ≤ 1: additive effect, meaning the combination is similar to the sum of their individual effects.
- 1 < FIC ≤ 4: indifference, meaning the combination does not significantly alter efficacy.
- FIC > 4: antagonism, meaning the combination reduces the effectiveness of the antibiotics.
For more explanations in the literature:
According to Doern (2014), Journal of Clinical Microbiology, 'When Does 2 Plus 2 Equal 5? A Review of Antimicrobial Synergy Testing', the FIC index is commonly used in synergy testing methods to determine whether antibiotic combinations act additively, synergistically, or antagonistically. The checkerboard method, which employs serial twofold dilutions, is one of the most widely used approaches for calculating FIC values and is frequently applied in research and clinical microbiology.