TABLE 1.
In vitro activity (μg/mL) of seven antimicrobial agents against the 61 “unique” strains of S. maltophilia studied here.
| Method | Agent | Class or sub-class | MIC50a | MIC90a | Range | % of susceptible isolatesb |
| Etest | Ceftazidime (CAZ) | Cephalosporins | 16 | >256 | 1–>256 | 37.7 |
| Minocycline (MIN) | Tetracyclines | 0.25 | 0.5 | 0.032–2 | 100 | |
| Levofloxacin (LEV) | Fluoroquinolones | 0.5 | 16 | 0.125–>32 | 80.3 | |
| Trimethoprim-sulfamethoxazole (SXT) | Folate pathway inhibitors | 0.25 | 0.5 | 0.125–>32 | 93.5 | |
| Amikacin (AMK) | Aminoglycosides | 32 | 256 | 2–>256 | 45.9 | |
| Ticarcillin-clavulanate (TTC) | Penicillins | 64 | >256 | 0.5–>256 | 37.7 | |
| Colistin (COL) | Polymyxins | 2 | 8 | 0.064–32 | 75.4 | |
| BMDc | Colistin | Polymyxins | 8 | 64 | <0.25–>256 | 32.7 |
aMIC90 and MIC50 values were defined as the lowest concentration of the antibiotic on a two-fold scale at which 90 and 50% of the isolates were inhibited, respectively. bSusceptibility breakpoints for S. maltophilia established by the Clinical and Laboratory Standards Institute (CLSI, 2019). For amikacin and colistin, CLSI breakpoints for P. aeruginosa were used. Intermediate and resistant strains were grouped together into a non-susceptible category. cBroth microdilution.