TABLE 2.

Killing activity of meropenem, imipenem, ceftriaxone, and ceftriaxone-vancomycin against the 26 S. pneumoniae isolates according to the penicillin G MIC

Antibiotic and concn	Change in log10 CFU/ml after incubation with isolates (n) at penicillin G MIC (μg/ml) of a:
	0.12 (n = 4)	0.25 (n = 3)	0.5 (n = 2)	1 (n = 4)	2 (n = 13)
Meropenem
CC (3 μg/ml)	≥3.4	≥3.4	3.2 ± 0.2	2.62 ± 0.25	2.46 ± 0.25
CC/2 (1.5 μg/ml)	≥3.4	≥3.4	3.2 ± 0.2	2.50 ± 0.23	2.38 ± 0.33
CC/4 (0.75 μg/ml)	≥3.4	≥3.4	3.2 ± 0.2	2.45 ± 0.20	2.36 ± 0.34
Imipenem
CC (2 μg/ml)	≥3.4	≥3.4	≥3.4	2.90 ± 0.52	2.95 ± 0.42
CC/2 (1 μg/ml)	≥3.4	≥3.4	3.3 ± 0.1	2.95 ± 0.63	2.98 ± 0.52
CC/4 (0.5 μg/ml)	≥3.4	≥3.4	3.3 ± 0.1	2.80 ± 0.67	2.91 ± 0.54
Ceftriaxone
CC (8.8 μg/ml)	≥3.4	≥3.4	3.0 ± 0.3	2.45 ± 0.24	2.08 ± 0.22
CC/2 (4.4 μg/ml)	≥3.4	≥3.4	2.9 ± 0.2	2.4 ± 0.2	1.98 ± 0.25
CC/4 (2.2 μg/ml)	≥3.4	≥3.4	2.8 ± 0.2	2.3 ± 0.2	1.90 ± 0.27
Ceftriaxone-vancomycinb
CC (8.8 and 2 μg/ml)	≥3.4	≥3.4	3.2 ± 0.1	2.75 ± 0.3	2.75 ± 0.32
CC/2 (4.4 and 1 μg/ml)	≥3.4	≥3.4	3.2 ± 0.1	2.65 ± 0.3	2.7 ± 0.4
CC/4 (2.2 and 0.5 μg/ml)	≥3.4	≥3.4	3.2 ± 0.1	2.60 ± 0.2	2.7 ± 0.4

^aValues represent mean (± standard deviation) change after 5 h of incubation with isolates at various penicillin MICs. 

^bConcentrations for the ceftriaxone-vancomycin combination are given respectively.