Table 1.
Antimicrobial susceptibility profile and molecular findings for the linezolid-resistant S. sanguinis strain (453-31288R) investigated in this study
| Parameter | Value/result |
|
|---|---|---|
| 453-31288R | 453-31288R60b | |
| Antimicrobial agent MIC (μg/ml) [susceptibility category]a | ||
| Linezolid | 32 [R] | 64 [R] |
| Chloramphenicol | 32 [R] | 32 [R] |
| Clindamycin | 2 [R] | 1 [R] |
| Virginiamycin | 2 | 2 |
| Quinupristin-dalfopristin | 4 [R] | 4 [R] |
| Retapamulin | 2 | 2 |
| Tiamulin | 32 | 32 |
| Tigecycline | ≤0.03 [S] | ≤0.03 [S] |
| Tetracycline | >16 [R] | >16 [R] |
| Doxycycline | 8 | |
| Vancomycin | 0.5 [S] | |
| Levofloxacin | 0.5 [S] | |
| Erythromycin | ≤0.12 [S] | |
| Penicillin | ≤0.06 [S] | |
| Molecular finding | ||
| cfr | Negative | |
| 23S rRNA | T2211C, T2406C, G2576T, and C2610T | |
| L3 | Wild type | |
| L4 | Wild type | |
| L22 | N56D | |
a
MIC interpretive criteria as published by CLSI M100-S23 (10), when available. The tigecycline susceptible breakpoint for Streptococcus spp. other than S. pneumoniae (≤0.25 μg/ml) approved by the Food and Drug Administration was applied (21). S, susceptible; I, intermediate; R, resistant.
b
MIC results and interpretations obtained for some antimicrobial agents tested against the S. sanguinis strain 31288R60 after 60 subcultures on drug-free blood agar plates.