Reference Antimicrobial Susceptibility Testing (AST) Data
CDC programs perform AST of bacterial and bloodstream Candida isolates collected in surveillance programs and isolates submitted to CDC from the reference laboratories for susceptibility testing because of unusual resistance. CDC laboratories default method is broth microdilution using frozen in-house prepared panels according to standards established by the Clinical and Laboratory Standards Institute (CLSI Documents: M7 for bacteria; M27 with M60 for Candida). Etest is a reference method for antifungal susceptibility to amphotericin B in accordance with CLSI M-27e4. CDC is making these data available online for use in setting breakpoints for interpretation of antimicrobial susceptibility testing.
The downloadable data contain tables and graphic representations that display minimum inhibitory concentration (MIC) distributions for various bacteria and Candida. We provide a description of the isolates tested with each dataset. CDC will continue to expand this database to include data from additional bacterial and fungal isolates and data from new antimicrobial drugs.
MIC data for Neisseria gonorrhoeae isolates can be found on the CDC Division of STD Prevention (DSTDP) Antimicrobial Resistant Gonorrhea website: STDs: Data & Statistics (Gonococcal Isolate Surveillance Project (GISP) Profiles and Annual Reports).
Downloadable Data & Additional Information
Distributions of MIC for bacteria
- Acinetobacter excel icon[XLS – 369 KB]
- Coagulase-negative Staphylococci (CNS) excel icon[XLS – 235 KB]
- Enterobacteriaceae excel icon[XLS – 3 MB]
- Enterococcus excel icon[XLS – 208 KB]
- Pseudomonas excel icon[XLS – 251 KB]
- Staphylococcus aureus excel icon[XLS – 548 KB]
Distributions of MIC for fungi
Additional Information
Printable Version: Supplementary Information pdf icon[PDF – 1 page]
Interpretation rules for MIC values for bacterial pathogens:
Lower range MIC (mcg/ml)
| LIMS MIC value (as entered) | MIC Distribution Interpretation |
|---|---|
| 0.059 | ≤ 0.06 |
| 0.119 | ≤ 0.12 |
| 0.249 | ≤ 0.25 |
| 0.49 | ≤ 0.5 |
| 0.9 | ≤ 1 |
| 1.9 | ≤ 2 |
| 3.9 | ≤ 4 |
Higher range MIC (mcg/ml)
| LIMS MIC value (as entered) | MIC Distribution Interpretation |
|---|---|
| 4.1 | ≥ 8 |
| 8.1 | ≥ 16 |
| 17 | ≥ 32 |
| 33 | ≥ 64 |
| 65 | ≥ 128 |
| 129 | ≥ 256 |
| 257 | ≥ 512 |
| 513 | ≥ 1024 |
Not-determined MIC
If the MIC values are not available or not determined within the they will appear in the dataset as one of these:
- “ND”
- A blank cell
- A single period “.”
If any of the above appear in the dataset, they should be interpreted as “not determined.”
Clinical specimen terms
Terms that require decoding: BAL = Bronchoalveolar lavage