[Deacylating activity of sera as a cause for the ineffectiveness of the treatment of experimental plaque in white mice with benzylpenicillin]. / Deatsiliruiushchaia aktivnost' syvorotok kak prichina neéffektiv-nosti lecheniia éksperimental'noi chumy belykh myshei benzilpenitsillinom

It was shown that serum of albino mice infected with plague microbe cells inactivated benzylpenicillin. Such deacetylating activity reached its peak by the 3rd day and after that decreased reaching by the 5th--7th day the level registered in non-infected animal and being apparently of non-specific character. Ampicillin proved to be 2 times more resistant to the effect of serum acylase as compared to benzylpenicillin. It was supposed that the ability of serum of infected animals to inactivate benzylpenicillin by splitting off phenylace acid was the cause of ineffective treatment of experimental plague of albino mice with comparatively low doses of the drug.