Table 2.

Killing activities of amoxicillin, cefotaxime, ceftriaxone, cefpirome, and meropenem alone or in combination with vancomycin, rifampin, or trovafloxacin after 6 h of incubation, according to ceftriaxone susceptibilitya

Agent used in combination and susceptibilityMean ± SD change in log10 CFU/ml after 6 h of incubation
AloneTrovafloxacinAmoxicillinCefotaximeCeftriaxone (5 μg/ml)Ceftriaxone (8 μg/ml)CefpiromeMeropenem
None (drug alone)
 Sb−2.9 ± 0.3−1.2 ± 1.2−2.7 ± 0.6−2.7 ± 0.6−2.7 ± 0.6−2.6 ± 0.5−3.2 ± 0.5
 Ic−2.6 ± 0.4−0.5 ± 0.9−2.0 ± 0.6−2.4 ± 0.5−2.5 ± 0.5−2.4 ± 0.5−2.8 ± 0.5
 Rd−2.8 ± 0.2−1 ± 1.2−0.8 ± 1.8−2.0 ± 0.6−2.4 ± 0.4−2.3 ± 0.5−2.7 ± 0.3
With vancomycin
 S−1.8 ± 0.4−2.2 ± 0.5−2.2 ± 0.3−2.9 ± 0.3−3.0 ± 0.3−3.0 ± 0.3−3.0 ± 0.4−3.0 ± 0.4
 I−1.6 ± 0.2−2.0 ± 0.3−2.0 ± 0.5−2.3 ± 0.6−2.3 ± 0.6−2.3 ± 0.6−2.3 ± 0.6−2.5 ± 0.6
 R−1.9 ± 0.2−2.2 ± 0.5−2.5 ± 0.6−2.8 ± 0.3−2.8 ± 0.4−2.7 ± 0.2−2.8 ± 0.3−2.8 ± 0.4
With rifampin
 S−1.1 ± 0.4−1.4 ± 0.3−1.3 ± 0.2−1.4 ± 0.2−1.5 ± 0.4−1.5 ± 0.4−1.5 ± 0.4−1.4 ± 0.2
 I−1.2 ± 0.5−1.4 ± 0.5−1.4 ± 0.4−1.5 ± 0.5−1.5 ± 0.5−1.6 ± 0.5−1.5 ± 0.5−1.6 ± 0.5
 R−1.6 ± 0.2−1.9 ± 0.4−2.1 ± 0.7−1.7 ± 0.4−1.7 ± 0.4−1.7 ± 0.5−1.7 ± 0.4−1.9 ± 0.8
With trovafloxacin
 S−3.3 ± 0.2−3.4 ± 0.4−3.3 ± 0.3−3.4 ± 0.4−3.3 ± 0.3−3.4 ± 0.4
 I−3.0 ± 0.4−2.9 ± 0.5−3.0 ± 0.3−3.0 ± 0.4−2.9 ± 0.5−3.0 ± 0.4
 R−2.8 ± 0.3−2.8 ± 0.1−2.8 ± 0.15−2.8 ± 0.1−2.8 ± 0.2−2.8 ± 0.1
  • a Antibiotics were tested at the mean concentration achieved in CSF after administration of doses currently recommended or proposed for the treatment of meningitis, as follows: amoxicillin, 6 μg/ml; cefotaxime, 5 μg/ml; ceftriaxone, 5 and 8 μg/ml; cefpirome, 4 μg/ml; meropenem, 3 μg/ml; trovafloxacin, 1 μg/ml; rifampin, 1 μg/ml, vancomycin, 2 μg/ml.

  • b Strains susceptible to ceftriaxone; n = 5.

  • c Strains intermediate to ceftriaxone; n = 11.

  • d Strains resistant to ceftriaxone; n = 4.