title: Comparison of levofloxacin, alatrofloxacin, and vancomycin for prophylaxis and treatment of experimental foreign-body-associated infection by methicillin-resistant Staphylococcus aureus.
abstract: The prophylactic and therapeutic activities of two fluoroquinolones, levofloxacin and alatrofloxacin (the L-Ala-L-Ala prodrug of trovafloxacin), were compared to those of vancomycin in two different experimental models of foreign-body-associated infections caused by methicillin-resistant but quinolone-susceptible Staphylococcus aureus (MRSA) isolates. In a guinea pig model of prophylaxis, subcutaneously implanted tissue cages were infected with 10(3) CFU of MRSA, which was a 100% infectious dose in control animals. A single dose of 50 mg of levofloxacin per kg of body weight, administered intraperitoneally 3 h before bacterial challenge, was more efficient than vancomycin for the prevention of infections in tissue cages with MRSA inocula of 10(4) and 10(5) CFU. In a rat model used to evaluate therapy of chronic tissue cage infection caused by MRSA, the efficacies of 7-day high-dose regimens of levofloxacin (100 mg/kg once a day [q.d.] or 50 mg/kg twice a day [b.i.d.]) or alatrofloxacin (50 mg/kg q.d.) were compared to the efficacy of vancomycin (50 mg/kg b.i.d.). Active levels of levofloxacin, trovafloxacin, and vancomycin were continuously present in tissue cage fluid, with the levels exceeding the minimal bactericidal concentrations for MRSA during therapy. The q.d. and b.i.d. regimens of levofloxacin had equivalent activities and were significantly (P < 0.05) more active than alatrofloxacin or vancomycin in decreasing the viable counts of MRSA in tissue cage fluids. No quinolone-resistant mutants emerged during therapy with either fluoroquinolone. The mechanisms explaining the inferior activity of alatrofloxacin compared to the activity of levofloxacin against chronic foreign-body-associated infections by MRSA are unknown.
authors.affiliation: Division of Infectious Diseases, Geneva University Hospital, CH-1211 Geneva 14, Switzerland. Pierre.vaudaux@hcuge.ch
authors.forename: Pierre
authors.initials: P
authors.lastname: Vaudaux
authors.forename: Patrice
authors.initials: P
authors.lastname: Francois
authors.forename: Carmelo
authors.initials: C
authors.lastname: Bisognano
authors.forename: Jacques
authors.initials: J
authors.lastname: Schrenzel
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Lew
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D019072:Antibiotic Prophylaxis; D004195:Disease Models, Animal; D024841:Fluoroquinolones; D005549:Foreign-Body Reaction / Q000188:drug therapy / Q000517:prevention & control; D006168:Guinea Pigs; D006801:Humans; D064704:Levofloxacin; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D064704:Levofloxacin; D014640:Vancomycin; C106856:alatrofloxacin; D015242:Ofloxacin