TABLE 3.
Numbers (and percentage) of strains against which each drug pair exhibited synergy
| Drug combinationa | No. (%) of strains for whichb: |
||
|---|---|---|---|
| Synergy was exhibited | MIC of ≥1 drug was brought into therapeutic range | MICs of both drugs were brought into therapeutic range | |
| FOX and IPM | 21 (100) | 21 (100) | 19 (90) |
| CXM and IPM | 17 (81) | 16 (76) | 3 (14) |
| DOR and IPM | 16 (76) | 15 (71) | 9 (43) |
| BIA and IPM | 15 (71) | 14 (67) | 10 (48) |
| CDR and IPM | 12 (57) | 12 (57) | 11 (52) |
| FAR and IPM | 12 (57) | 12 (57) | 0 (0) |
| CFR and TEB | 12 (57) | 0 (0) | 0 (0) |
| ETP and IPM | 10 (48) | 10 (48) | 0 (0) |
| CDN and IPM | 6 (29) | 5 (24) | 1 (5) |
| CPD and IPM | 6 (29) | 6 (29) | 0 (0) |
| CDN and TEB | 6 (29) | 2 (10) | 0 (0) |
| CXM and CDN | 5 (24) | 2 (10) | 1 (5) |
| CDN and BIA | 3 (14) | 1 (5) | 0 (0) |
a
FOX, cefoxitin; IPM, imipenem; CXM, cefuroxime; DOR, doripenem; BIA, biapenem; CDR, cefdinir; FAR, faropenem; CFR, cefadroxil; TEB, tebipenem; ETP, ertapenem; CDN, cefditoren; CPD, cefpodoxime.
b
Extrapolated MICs were calculated using the FICI for each drug pair and clinical strain. The therapeutic range was defined as MICs at or below the CLSI breakpoints for cephalosporins (≤16 μg/ml, susceptible; ≤64 μg/ml, intermediately susceptible) and carbapenems (≤4 μg/ml, susceptible; ≤8 μg/ml, intermediately susceptible).