Antibiotic MIC Calculator
🧪 MIC Results
Minimum Inhibitory Concentration (MIC)
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Antibiotic
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tested compound
Wells Showing Growth
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out of total wells
% Inhibition at MIC
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relative to growth control
Concentration Range
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µg/mL tested
Concentration Results Table
| Well | Conc. (µg/mL) | Result | Note |
|---|
How to Use the Antibiotic MIC Calculator
Set your starting concentration and dilution factor, then click "Generate Well Panel" to create an interactive well grid. Click each well to mark it as Growth (turbid, 🔴) or No Growth (clear, 🟢). The MIC is automatically identified as the lowest concentration showing no growth.
- Starting Concentration: Highest antibiotic concentration tested, typically 256 µg/mL.
- Dilution Factor: Standard broth microdilution uses 2-fold serial dilutions.
- Growth Control: The last well (no antibiotic) should always show growth — confirms viable inoculum.
- MIC: The lowest concentration in which no visible growth (turbidity) is observed.
MIC Definition and Interpretation
MIC = Lowest concentration that inhibits visible bacterial growth
Concentrations tested (2-fold serial dilution, starting 256 µg/mL):
256 → 128 → 64 → 32 → 16 → 8 → 4 → 2 → 1 → 0.5 µg/mL
MIC Interpretation (EUCAST/CLSI breakpoints vary by organism):
Susceptible (S): MIC ≤ breakpoint
Intermediate (I): MIC = intermediate range
Resistant (R): MIC ≥ resistance breakpoint
Concentrations tested (2-fold serial dilution, starting 256 µg/mL):
256 → 128 → 64 → 32 → 16 → 8 → 4 → 2 → 1 → 0.5 µg/mL
MIC Interpretation (EUCAST/CLSI breakpoints vary by organism):
Susceptible (S): MIC ≤ breakpoint
Intermediate (I): MIC = intermediate range
Resistant (R): MIC ≥ resistance breakpoint
Clinical MIC Breakpoints (General Reference)
- Ampicillin vs E. coli: S ≤ 8 µg/mL, R ≥ 32 µg/mL (EUCAST)
- Ciprofloxacin vs E. coli: S ≤ 0.25 µg/mL, R ≥ 1 µg/mL (EUCAST)
- Gentamicin vs S. aureus: S ≤ 1 µg/mL, R ≥ 4 µg/mL (EUCAST)
- Vancomycin vs S. aureus: S ≤ 2 µg/mL, R ≥ 8 µg/mL (EUCAST)
- Always refer to current EUCAST or CLSI guidelines for organism-specific breakpoints.