Table 2.
Susceptibility rates for first- and second-generation tetracycline-class drugs against common gram-positive pathogens [27,28].
| Organism | Antibiotica | MIC (µg/mL) |
% Susceptible / % Resistant |
||
|---|---|---|---|---|---|
| 50% | 90% | CLSI | EUCAST | ||
| Streptococcus pneumoniae | Tetracycline | 0.5 | >8 | 73.2 / 26.7 | 73.2 / 26.7 |
| Doxycycline | 0.25 | 8 | 71.3 / 26.8 | 73.9 / 24.7 | |
| Minocycline | NR | NR | 71.7 / 27.3b | 72.7 / 26.4 | |
| Streptococcus pyogenes | Tetracycline | ≤0.25 | >8 | 80.3 / 19.7 | 79.6 / 19.7 |
| Doxycycline | 0.12 | 8 | 81.2 / 16.0 | 80.2 / 18.8 | |
| Minocycline | NR | NR | 78.0 / 20.7 | 78.0 / 22.0 | |
| Methicillin-resistant Staphylococcus aureus | Tetracycline | ≤0.25 | 2 | 91.2 / 8.0 | 88.1 / 9.0 |
| Doxycycline | 0.12 | 1 | 96.2 / 0.6 | 93.5 / 5.5 | |
| Minocycline | NR | NR | 97.2 / <0.1 | 88.3 / 11.3 | |
CLSI: Clinical and Laboratory Standards Institute; EUCAST: European Committee on Antimicrobial Susceptibility Testing; MIC: minimum inhibitory concentration; NR: not recorded.
aTetracycline is considered a first-generation tetracycline-class drug. Doxycycline and minocycline are second-generation tetracycline-class drugs.
bUsing CSLI 2013 susceptibility breakpoint for doxycycline of ≤0.25 μg/mL applied to the minocycline.