Levofloxacin: serum bactericidal activity against methicillin-resistant Staphylococcus aureus isolates.
The aim of this study was to assess the serum bactericidal activity (SBA) of levofloxacin compared with that of ofloxacin against methicillin-resistant Staphylococcus aureus (MRSA) isolates. Serum from 10 healthy volunteers (seven females, three males) was collected after a single oral dose of either levofloxacin (500 mg) or ofloxacin (400 mg). Subjects were allocated randomly to treatment after at least a 1 week interval between antibiotic regimens. Three well-defined MRSA strains were tested, each susceptible to levofloxacin and ofloxacin, with different levels of resistance to methicillin (HBD 456, HBD 3 and HBD 2; class 1, 2 and 3 Tomasz heterogeneous resistance, respectively) together with a methicillin-susceptible (MSSA) reference strain (S. aureus ATCC 25,923). SBA was tested in vitro by a microtitration method 15 min before dosing and at 1, 4, 8 and 12 h after drug absorption. Levofloxacin was significantly more bactericidal than ofloxacin against all strains of S. aureus tested (SBA > or = 1:2). An SBA was recorded for only a short period with ofloxacin, and thereafter only bacteriostatic activity remained. This study, therefore, confirms the superior activity of levofloxacin over that of ofloxacin against MSSA and MRSA.
CHU Bichat-Claude Bernard, Paris, France.
C
C
Muller-Serieys
D
D
Decré
C
C
Benoit
C
C
Bigot
B
B
Maubert
C
C
Carbon
D000890:Anti-Infective Agents / Q000494:pharmacology*; D006801:Humans; D064704:Levofloxacin; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000494:pharmacology*; D015610:Serum Bactericidal Test; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
D000890:Anti-Infective Agents; D064704:Levofloxacin; D015242:Ofloxacin