Table 1.
Description of the biological model and experimental database. Three antibiotics have been tested: gentamicin which inhibits protein synthesis, ciprofloxacin which prevents DNA supercoiling, and amoxicillin which impedes the cell wall synthesis. For each of them are listed the clinical breakpoints from EUCAST4 for E. coli, the tested concentrations, the references of susceptible and resistant strains of E. coli, with the corresponding MICs (measured in Vitek®2). Each “experiment” consisted in testing, on one date, one strain in presence of one antibiotic at multiple concentrations (including 0) and acquiring around 50 spectra per concentration; it was replicated on different dates. The overall database contains 3668 spectra of single bacteria. Note that E. coli ATCC 25922 strain is the AST quality-control reference recommended by EUCAST.
| Antibiotic | Gentamicin | Ciprofloxacin | Amoxicillin |
|---|---|---|---|
| MIC breakpoints for E. coli (µg/mL) | |||
| Susceptible | S ≤ 2 | S ≤ 0.25 | S ≤ 8 |
| Resistant | R > 4 | R > 0.5 | R > 8 |
| Tested concentrations (µg/mL) | 0.5, 2, 8 (128, 256)* | 0.005, 0.015, 0.064, 0.25, 1 | 2, 4, 8, 16 |
| Susceptible strain | ATCC 25922 (EC1) | ATCC 25922 (EC1) | ATCC 25922 (EC1) |
| MIC (µg/mL) | 1 | 0.008 | 6 |
| Number of experiments/spectra | 7/886 | 7/889 | 5/604 |
| Resistant strain | ATCC 35421 (EC2) | API 9210041 (EC3) | ATCC 35421 (EC2) |
| MIC (µg/mL) | >256 | 3 | >256 |
| Number of experiments/spectra | 3/404 | 3/399 | 3/486 |
*Only tested on resistant strain EC2.