TABLE 1.

Fluoroquinolone activity with clinical isolates of S. pneumoniae^a

Compound	MIC₉₀	MPC₅₀^b	MPC₉₀^b	C_max	Half-life (h)	Time > MPC₅₀^b,^c	Time > MPC₉₀^b,c	AUC_0-24/MIC₉₀^c	C_max/MIC₉₀^c
Gemifloxacin	0.03-0.063	0.25	1	1.6	7-8	14	4	140-280	27-53
Moxifloxacin	0.25	0.5	2	4.5	12-14	24	18	190	18
Gatifloxacin	0.5	1	4	4.2	8-10	12	1-2	103	8.4
Levofloxacin	1	2	8	5.7	5-7	9	0	48	5.7

Of the 146 isolates tested, 43 were nonsusceptible to penicillin. Fluoroquinolone susceptibility was unaffected by loss of susceptibility to penicillin. Test cultures, growing in liquid medium, were prepared from bacterial lawns grown directly from frozen samples (2). All concentrations in the table are in milligrams per liter, and times are in hours. (Some of these data were previously reported [2].)

Data taken as MPC were designated provisional in previous work (MPC_pr) because a twofold overestimate arises from the high inoculum used (>10¹⁰ cells per plate). MPC_pr is a conservative estimate of MPC.

Pharmacokinetic parameters were calculated by using total drug concentration. C_max applies to doses recommended by the manufacturer (listed in reference 3). AUC_0-24, area under the concentration-tin curve from 0 to 24 h.