Influence of Haw Pectin-derived pectic oligosaccharieds combined with fluoroquinolones on mutant prevention concentration of Staphylococcua aureus

Abstract

Objective To provide supporting evidence for logical use of antibiotics by exploring the influence of combination therapy with Haw Pectin-derived pectic oligosaccharieds and fluoroquinolones on mutant prevention concentration of Staphylococcus aureus. Methods Minimal inhibitory concentrations (MIC) of levofloxacin and ciprofloxacin for staphylococcus aureus and quality control (ATCC25923) were determined by the standard two-fold agar dilution methods. MPC of fluoroquinolones for the strains were determined by spreading 1010cfu/ml coccus on agar plates containing single or two drugs at different concentrations. The values of MPC50 and MPC90 were calculated. Results For 30 clinical isolated ciprofloxacin and oxacillin-susceptible Staphylococcus aureus, MPC of levofloxacin alone was 2-64 mg/L and MPC90 was 32 mg/L and they reduced to 0.5-16mg/L and 8 mg/L on levofloxacin combined with pectic oligosaccharieds; MPC of of ciprofloxacin alone was 1-32 mg/L and MPC90 was 16 mg/L and they declined to 0.25-8 mg/L and 4 mg/L on ciprofloxacin plus pectic oligosaccharieds. Conculusions Combination with Haw Pectin-derived pectic oligosaccharieds can decrease MPCs of levofloxacin and ciprofloxacin, reduce the proliferation of drug-resistant mutants, and prevent the occurrence of drug resistance. Key words: Fluoroquinolone; Combination therapy; Staphylococcus aureus; Mutant prevention concentration