Moxifloxacin superior to vancomycin for treatment of bone infections—a study in rats

Abstract

Background Increasing resistance rates towards conventional antibiotics necessitate investigations of the efficacy of newly developed antibiotics. Thus, in a rat study, we compared the efficacy of moxifloxacin and vancomycin in the treatment of a local Staphylococcus aureus bone infection.

Method The femoral medullary cavities of 36 Wistar rats were contaminated with 100 μL of an oxacillin-sensitive Staphylococcus aureus strain (ATCC 29213) at 10⁸cfu/mL. On the seventh day, antibiotic treatment with moxifloxacin (10 mg/kg twice daily i.p.) or vancomycin (15 mg/kg twice daily i.p.) was commenced in 12 animals each. 12 control animals were left untreated. After 21 days, the infected femurs were explanted and the bacterial counts (cfu/g) were determined.

Results In the control group, a median of 3.42 × 10⁶cfu/g (LQ/UQ 1.09 × 10⁶/ 1.55 × 10⁷) was cultured, with a median of 2.53 × 10⁶cfu/g (LQ/UQ 1.95 × 10⁶/ 4.25 × 10⁶) in the vancomycin group and a median of 2.49 × 10⁵cfu/g (LQ/UQ 2.84 × 10⁴/ 3.75 × 10⁵) in the moxifloxacin group.The bacterial count was reduced by treatment with moxifloxacin both in comparison with the control group (p < 0.001), and in comparison with treatment with vancomycin (p < 0.001). There was no statistically significant difference between the vancomycin group and the control group (p = 0.53).

Interpretation In contrast to vancomycin, moxifloxacin proved to be an effective antibiotic for the treatment of bone infections due to Staphylococcus aureus in our animal model.

Author contributions

TK, JB, KL, NL, JG designed the study. TK, JB, HS, NL gathered the data. TK, JB, NL, KL analyzed the data. TK, NL, KL wrote the manuscript. MH, NL did the statistical analysis. TK, JB, HS, MH, JG, NL, KL ensured the accuracy of the data and analyses.