Background: Methicillin-resistant Staphylococcus aureus (MRSA)
infections are largely preceded by colonization with MRSA.
Hochuekkito is the formula composing 10
herbal medicines in traditional
Kampo medicine to treat infirmity and to stimulate immune functions. We evaluated the efficacy of
hochuekkito extract (HET) against MRSA colonization using a nasal
infection murine model. Methods: We evaluated the effects of HET as follows: (1) the growth inhibition by measuring turbidity of bacterial culture in vitro, (2) the nasal colonization of MRSA by measuring bacterial counts, and (3) the splenocyte proliferation in mice orally treated with HET by the ³H-
thymidine uptake assay. Results: HET significant inhibited the growth of MRSA. The colony forming unit (CFU) in the nasal fluid of HET-treated mice was significantly lower than that of HET-untreated mice. When each single crude
drug-Astragali
radix, Bupleuri radix,
Zingiberis rhizoma, and Cimicifugae rhizome-was removed from
hochuekkito formula, the effect of the formula significantly weakened. The uptake of ³H-
thymidine into murine splenocytes treated with HET was significantly higher than that from untreated mice. The effects of the modified formula described above were also significantly weaker than those of the original formula. Conclusions:
Hochuekkito is effective for the treatment of MRSA nasal colonization in the murine model. We suggest HET as the therapeutic candidate for effective
therapy on nasal cavity colonization of MRSA in humans.