Abstract
Summary
Three cultures of staphylococci, one of Streptococcus pyogenes and 3 of pneumococci, Types I, II, and III, showed wide differences in degree of resistance after cultivation in presence of penicillin.
Loss in virulence for mice was associated with increase in resistance. Serial passage of one such strain through mice failed to restore virulence.
Passage in vivo in the presence of penicillin failed to increase specific resistance of a strain of Staphylococcus aureus.
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