The effect of erythromycin on toxoplasma gondii in vitro

RESUMO

The comparative in vitro effect of Erythromycin Lactobionate (E) on two different strains of T. gondii was assayed. Monolayers of mammalian cells in 4 ml of MEM + 2% calf serum were inoculated with Toxoplasma (1.5 to 2.5 x 10 5 parasites per flask) and thereafter incubated with different concentrations of E at 37o C for 24 h. Monolayers were then fixed and stained by Giemsa and Mean Number of Infective Units (MNIU) assessed. Human lung fibroblast cultures showed total inhibition and/or death of T. gondii with 100-200 mcg/ml of E and 81% decrease of MNIU at 20 mcg/ml of E (P< 0,05 as compared to controls) for both strains. Later experiments on monkey kidney cells showed a difference in sensitivity to E, between both T. gondii strains while strains A showed 1 61% decrease in MNIU at 5 mcg/ml E (P< 0.005) strain B was sensitive only to a concentration of 50 mcg/ml E (66% reduction of MNIU, P< 0.005). A distint effect of E against intracellular T. gondii was shown. Results indicate that E, at concentrations similar to those reached in the human serum standard IV dose, may prove effective against infections due to sensitive Toxoplasma strains. Initial experiments suggest that the combination of E (1,25 mcg/ml) plus sulfisoxazole (0,25-25 mcg/ml), significantly increase the anti-toxoplasma effect of the individual agents