Table 1.
MIC distribution for CXA-101 alone and in combination with tazobactam and various comparator agents tested against selected Enterobacteriaceae species, K. pneumoniae strains, and P. mirabilis strainsa
| Antimicrobial agent(s)b | No. of isolates (cumulative %) inhibited at the following concn (μg/ml) of CXA-101 or comparator agentc: |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.12 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 or >16 | 64 or >32 | >64 | |
| CXA-101 | 2 (0.3) | 6 (1.0) | 5 (1.6) | 11 (3.0) | 35 (7.3) | 78 (16.9) | 109 (30.33) | 136 (47.10) | 429 (100.0) | — | |
| CXA-101 combinations | |||||||||||
| CXA-TAZ4 | 4 (0.5) | 36 (4.9) | 102 (17.5) | 143 (35.1) | 83 (45.4) | 95 (57.1) | 63 (64.9) | 95 (76.6) | 190 (100.0) | — | — |
| CXA-TAZ2 | 0 (0.0) | 24 (3.0) | 60 (10.4) | 107 (23.6) | 76 (32.9) | 71 (41.7) | 65 (49.7) | 128 (65.5) | 280 (100.0) | — | — |
| CXA-TAZ(2:1) | 0 (0.0) | 2 (0.3) | 13 (1.9) | 21 (4.4) | 91 (15.7) | 209 (41.4) | 190 (64.9) | 163 (85.0) | 122 (100.0) | — | — |
| CXA-TAZ(4:1) | 0 (0.0) | 2 (0.3) | 8 (1.2) | 19 (3.6) | 43 (8.9) | 118 (23.4) | 225 (51.2) | 209 (76.9) | 187 (100.0) | — | — |
| CXA-TAZ(8:1) | 0 (0.0) | 1 (0.1) | 8 (1.1) | 13 (2.7) | 24 (5.7) | 68 (14.1) | 159 (33.7) | 247 (64.1) | 291 (100.0) | — | — |
| Comparator agents | |||||||||||
| Ceftazidime | — | — | — | — | — | 39 (4.8) | 7 (5.7) | 4 (6.2) | 66 (14.3) | 204 (39.5) | 491 (100.0) |
| Ceftriaxone | — | 11 (1.4) | 4 (1.9) | 6 (2.6) | 17 (4.7) | 33 (8.8) | 53 (15.3) | 102 (27.9) | 128 (43.7) | 457 (100.0) | — |
| Cefepime | 44 (5.4) | 40 (10.4) | 81 (20.6) | 98 (32.4) | 91 (43.7) | 51 (49.9) | 46 (55.6) | 58 (62.8) | 302 (100.0) | — | — |
| Imipenem | — | — | 548 (67.6) | 104 (80.4) | 74 (89.5) | 24 (92.5) | 13 (94.1) | 48 (100.0) | — | — | — |
| Meropenem | 685 (79.4) | 38 (89.3) | 14 (91.0) | 5 (91.6) | 7 (92.5) | 7 (93.3) | 10 (94.6) | 44 (100.0) | — | — | — |
| Piperacillin-tazobactam | — | — | — | 78 (9.6) | 51 (15.9) | 78 (25.5) | 74 (34.7) | 110 (48.2) | 93 (59.7) | 95 (71.4) | 232 (100.0) |
CXA-101 alone and in combination with tazobactam and various comparator agents were tested against 690 ceftazidime-resistant strains from selected Enterobacteriaceae species, 53 KPC-producing K. pneumoniae strains, and 68 ESBL-producing P. mirabilis strains. The selected Enterobacteriaceae species include E. coli (224 strains), K. pneumoniae (186 strains), indole-positive Proteus (82 strains), Enterobacter spp. (90 strains), and Citrobacter spp. (108 strains).
CXA-101 alone and in combination with tazobactam (TAZ) were tested as follows: CXA-TAZ4 and CXA-TAZ2, CXA-101 and tazobactam with taxobactam at a fixed concentration of 4 μg/ml and 2 μg/ml, respectively; CXA-TAZ(2:1), CXA-TAZ(4:1), and CXA-TAZ(8:1), CXA-101 and tazobactam at ratios of 2:1, 4:1, and 8:1, respectively.
The MIC50s are underlined. —, concentration not tested.