Table 1.

Results of synergy testing with gram-negative organisms

OrganismMIC (μg/ml)Result for drug combination at time (h)a
ClinafloxacinCeftazidimeAmikacinImipenemClinafloxacin + ceftazidimeClinafloxacin + amikacinClinafloxacin + imipenem
612246122461224
P. aeruginosa 1>128>6432Sy (0.25/32)AdAdSy (0.25/8)AdAdAdSy (0.25/2)Ad
2>128>64128AdSy (0.25/32)AdAdSy (0.25/32)AdAdSy (0.25/64)Ad
26484AdAdAdAdAdAdSy (0.25/0.5)AdAd
S. maltophilia 2128>64>128AdSy (0.25/16)Sy (0.25/16)AdAdAdAdSy (0.25/64)Sy (0.25/64)
1>12832>128AdSy (0.5/32)AdAdAdAdAdAdAd
112832>128AdSy (1/32)AdAdAdAdAdAdAd
Acinetobacterspp.4840.25Sy (0.5/2)AdAdSy (0.5/1)AdAdSy (0.5/0.06)AdAd
43220.5AdAdAdAdSy (1/1)AdAdSy (1/0.12)Sy (1/0.12)
0.25840.25AdAdSy (0.06/2)AdSy (0.06/1)Sy (0.06/1)AdSy (0.06/0.06)Ad
B. cepacia 24>6416AdSy (0.5/2)Sy (0.5/2)AdSy (0.5/32)Sy (0.5/32)AdAdSy (0.5/8)
423264AdSy (2/1)AdAdAdAdSy (2/32)Sy (2/32)Sy (2/32)
28>64128AdAdSy (0.5/2)AdAdSy (0.5/16)Sy (0.5/32)Sy (0.5/32)Sy (0.5/32)
E. coli 20.12520.125AdAdAdSy (0.5/1)AdAdAdAdAd
10.2540.06AdAdAdAdAdAdAdAdAd
464320.5AdAdAdAdSy (2/16)AdSy (2/0.25)Sy (2/0.25)Ad
K. pneumoniae 10.510.06AdAdAdAdAdAdAdAdSy (0.25/0.03)
4>12810.25AdSy (1/32)Sy (1/32)AdSy (1/0.5)AdAdAdAd
8110.125AdAdAdAdAdAdAdAdAd
E. cloacae 2821AdAdAdAdAdAdAdAdAd
4820.125AdAdAdAdSy (2/1)AdAdAdAd
10.520.5Sy (0.12/0.12)AdSy (0.12/0.12)AdAdAdAdAdAd
E. aerogenes 2124AdAdAdAdAdAdAdAdAd
C. freundii 2120.125AdSy (0.5/0.5)AdAdSy (0.5/1)Sy (0.5/1)AdSy (0.5/0.06)Ad
16420.25Sy (0.25/16)AdAdAdSy (0.25/0.5)AdSy (0.25/0.12)AdAd
16420.25AdSy (0.25/16)Sy (0.25/16)AdSy (0.25/1)Sy (0.25/1)AdSy (0.25/0.12)Sy (0.25/0.12)
S. marcescens 4142AdSy (1/0.12)Sy (1/0.12)AdSy (1/2)Sy (1/2)AdAdAd
0.5122AdSy (0.12/0.25)Sy (0.12/0.25)AdSy (0.12/1)AdAdSy (0.12/0.5)Sy (0.12/0.5)
10.521Sy (0.25/0.12)Sy (0.25/0.12)AdSy (0.25/1)Sy (0.25/1)AdAdSy (0.25/0.25)Sy (0.25/0.25)
P. mirabilis 2ND168NDNDNDAdAdAdAdSy (0.5/1)Sy (0.5/1)
0.5ND168NDNDNDAdAdAdAdSy (0.12/0.5)Sy (0.12/0.5)
P. stuartii 10.2511Sy (0.25/0.06)AdSy (0.25/0.06)Sy (0.25/0.25)AdSy (0.25/0.25)AdSy (0.25/0.5)Sy (0.25/0.5)
20.520.5Sy (0.5/0.06)Sy (0.5/0.06)Sy (0.5/0.06)AdSy (0.5/1)Sy (0.5/1)AdAdSy (0.5/0.12)
M. morganii 8>12882Sy (1/4)AdSy (1/4)AdAdAdAdAdAd
  • a Sy, synergistic; Ad, additive. Values in parentheses are MICs, i.e., the lowest concentrations (in micrograms per milliliter) of each compound that yielded a ≥2-log10decrease in CFU per milliliter compared to the more active single compound. ND, not done because of trailing endpoints.