Abstract
Summary
1. By growing S. faecalis (ATCC 8043) in a liquid medium containing successively higher concentrations of 2,4-diamino-5 (3'4'-dichlorphenyl)-6-methylpyrimidine (SK 5265), a thousand fold increase in resistance as evidenced by complete inhibition of growth and a more than two hundred thousand fold increase in resistance as demonstrated by the half maximum inhibition technic has been achieved. 2. No morphologic differences between the sensitive S. faecalis (8043) and the resistant variant could be detected. 3. The resistant organism has lost its requirement for supplementary PGA in Difco Folic Acid Assay Medium and certain other PGA deficient media.
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