TABLE 2.
DHFR gene analysis and MIC ranges of Tmp and dihydrophthalazine antifolates toward selected enterococci
| Species | No. of strains | Van phenotype | MIC range (μg/ml)
|
Presence of DHFR genea
|
|||||
|---|---|---|---|---|---|---|---|---|---|
| Tmp | BAL0030543 | BAL0030544 | BAL0030545 | dfrE | folA | dfrF | |||
| E. faecalis | 1 | Vanr | ≤0.25 | ≤0.25 | ≤0.25 | ≤0.25 | + | − | − |
| 4 | Vans/r | ≤0.25-1 | ≤0.25 | ≤0.25-0.5 | ≤0.25-0.5 | + (K88N, A5T, or H153R) | − | − | |
| 1 | Vans | 16 | 0.5 | 0.5 | 1 | + (A5T + K88N + F102Y) | − | − | |
| 2 | Vanr | 128 | 1 | 1-2 | 1 | + | − | − | |
| 2 | Vans | >128 | >128 | >128 | >128 | + | − | + | |
| E. faecium | 2 | Vans | 0.5 | ≤0.25 | ≤0.25 | ≤0.25 | − | + | − |
| 2 | Vans | ≤0.25-0.5 | ≤0.25 | ≤0.25 | ≤0.25 | − | + (M145I or R52H) | − | |
| 1 | Vans | 0.5 | ≤0.25 | ≤0.25 | ≤0.25 | + (A5T + K88N) | + (M145I) | − | |
| 4 | Vanr | >128 | 2-4 | 2-4 | 2-4 | − | + | − | |
| 1 | Vanr | >128 | >128 | >128 | >128 | − | + | + | |
a
The presence and absence of particular DHFR genes are indicated by “+” and “−”, respectively; amino acids differing from those in the wild-type enzyme are shown in parentheses.