Overview
The MIC is the lowest antimicrobial concentration that inhibits visible growth of a microorganism under standardized dilution testing conditions used for phenotypic AST.
Classification
| Format | Typical use | Controls |
|---|---|---|
| Broth microdilution | Panels/automated cards (related) | Inoculum, broth, QC |
| Broth macrodilution | Reference/special testing | Volumes, inoculum, QC |
| Agar dilution | Reference/special sets | Agar mix, spots, QC |
Morphologic Features
Endpoints are turbidity/growth absence, not cellular morphology. Skipped wells and trailing haze require SOP-defined handling and purity checks.
Laboratory Characteristics
- Growth and sterility controls as applicable
- Verified inoculum density
- Intact panel/plate dilutions
- Documented MIC and category
- QC within institutional dilution ranges
Reference Intervals
QC acceptable MIC ranges and clinical breakpoints are institutional, verify currently adopted CLSI or EUCAST edition and local charts. Do not treat secondary-source tables as live reporting tools.
Clinical and Laboratory Significance
Valid MICs support category assignment for clinical use. Invalid inoculum or QC failure requires repeat before release.
Differential Considerations
Differentiate true elevated MIC (resistance) from heavy inoculum, wrong medium, contaminated wells, misread trailing, and QC system failure.
Comparison Tables
MIC reporting gates
| Finding | Laboratory action | Avoid |
|---|---|---|
| QC MIC out of range | Hold agent/run; troubleshoot | Releasing “close” values |
| Trailing haze | Apply SOP endpoint rule | Guessing midpoint |
| Dose question from MIC | Report category only | Dosing advice |
Disk vs MIC complementarity
| Disk diffusion | MIC dilution | Shared gates |
|---|---|---|
| Zone diameter | Concentration endpoint | Inoculum + media + QC |
| Agar gradient diffusion | Serial dilutions | Adopted breakpoints |
| Category S/I/R (or local) | Category from MIC | No therapy advice |
Classification Frameworks
Not applicable.
Laboratory Notes
- Never provide treatment or dosing from MIC values
- Hedge breakpoints and QC ranges as institutional
- Emphasize inoculum, media, reading, and QC on every panel
References
Authoritative textbooks, guidelines, and reviews supporting this reference entry. Verify reference intervals, critical limits, and reflex criteria against institutional protocols and current guideline editions.
Textbooks
- Forbes BA, Sahm DF, Weissfeld AS. Bailey & Scott's Diagnostic Microbiology. 15th ed. Elsevier; 2020.
- Mahon CR, Lehman DC, Manuselis G. Textbook of Diagnostic Microbiology. 6th ed. Elsevier; 2018.
- Carroll KC, Hobden JA, Miller S, et al. Jawetz, Melnick, & Adelberg's Medical Microbiology. 28th ed. McGraw-Hill; 2019.
- Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology. 9th ed. Elsevier; 2021.
CLSI and Professional Guidelines
- Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing. CLSI document M100 (verify current edition and institutional adoption).
- Centers for Disease Control and Prevention / NIH. Biosafety in Microbiological and Biomedical Laboratories (BMBL). Current edition (verify institutional adoption).
Frequently Asked Questions
Common questions about using this MIC foundational topics Medical Laboratory Library reference in Medical Laboratory Science education.
What is the MIC laboratory reference?
MIC is a Foundational Topics entry in the LabPedia Medical Laboratory Library, written for Medical Laboratory Science reference lookup.
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Read the structured sections for quick orientation, then follow related links into Academy lessons or Challenge Center practice when you need teaching or assessment.
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Can reference details vary between laboratories?
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