In vivo effect of minocycline alone and in combination with immunotherapy against pythium insidiosum

This study examined the effect of minocycline alone and in combination with immunotherapy against pythiosis. Twenty rabbits, aged three months old and subcutaneously inoculated with Pythium insidiosum zoospores were divided into four groups (n = 5): treated with minocycline (10 mg/kg/day twice daily), treated with immunotherapy (34 mg subcutaneously every 14 days), treated with minocycline plus immunotherapy, and untreated (control group). The treatments were started 30 days after inoculation and continued for 70 days. The subcutaneous nodular injury areas in infected groups were measured every seven days after the beginning of treatment. Only the rabbits that developed lesions were selected for this study. When compared with the control group over 70 days, the minocycline and minocycline plus immunotherapy groups of rabbits with pythiosis showed significantly reduced injuries. The histopathology showed the presence of inflammation, macrophages and eosinophils. Grocott's staining revealed irregular hyphae-like structures that were ramified and occasionally septate. Our results suggest that minocycline has fungistatic activity and that the combination of minocycline and immunotherapy is more effective than the individual therapies tested.