Antitoxic Action of A. viridans on Exotoxin, Produced by S. aureus

Abstract

One of the most important indices of staphylococcal toxin is leukotoxic activity. During investigation, this characteristic was examined in 94 test samples and 36 control samples of toxin, obtained from two cultures of S. aureus -«Lossman» and «Lor». When analyzing results, we calculated neutrophil damage index (NDI): correlation of the number of damaged neutrophils and total number of found ones. It was established that samples of toxin obtained from test cultures of staphylococci survived during repeated contact with A. viridans, were characterized by reliably decreased (p < 0.001) leukotoxic activity. For example, NDI for control samples of undiluted toxin was equal to 0.91 and 0.8; for test samples -0.26 and 0.62. Variance in leukotoxic activity was observed even upon dilution of test samples of toxin as compared with control ones. So, whereas NDI in 81 times' diluted control samples of toxin was equal to 0.84 and 0.75, this index in test samples appeared to be 0.19 and 0.57, accordingly. Lethal characteristics were examined in 157 test samples and 85 control samples of toxin during intravenous introduction to white mice in quantity of 0.2 mL. Dates of animals' death were duly noted. Evidently, 157 test samples of toxin examined by us turned to be inactive: all animals survived. At the same time, control samples of toxin were distinguished by clearly expressed lethal activity: almost all mice died during 5 days. Only two mice survived of 85 ones. Similar results were obtained during investigation of necrotic characteristics of the same 157 samples of toxin. Toxins obtained from strains of staphylococci not contacted with aerococci caused, as a rule, necrosis of rabbit skin. At the same time, toxins obtained from strains of staphylococci contacted with A. viridans No. 11 caused feebly marked necrotic reaction only. Therefore, A. viridans No. 11 producing H₂0₂, have not only bacteriostatic and bactericide influence on staphylococcus, but also change its characteristics down to loss of virulence thereby. It may be supposed that aerococci completely disturb synthesis or impede formation of any fraction of staphylococcal toxin.