Metabolic and Genetic Investigations of Nutritionally Exacting Strains of Staphylococcus pyogenes

Abstract

COAGULASE-POSITIVE strains of Staphylococcus pyogenes, taken at random from material phage-typed at Hammersmith Hospital and at the Central Public Health Laboratory, Colindale, were tested for their nutritional character. All but 50 of the 926 strains grew well on a defined medium (based on that of Fildes et al.¹) containing valine, leucine, glycine, proline, aspartic acid, methionine, phenylalanine, arginine, histidine, cysteine, thiamine and nicotinic acid in a glucose-citrate-salts-agar base. Of the 50 exacting strains, all but 4 grew on the medium further supplemented as follows : tryptophan, 12 strains ; threonine, 6 strains ; alanine, 4 strains; tyrosine, 3 strains; lysine, 2 strains; tryptophan and tyrosine, 9 strains; tryptophan and isoleucine, 2 strains; tryptophan and biotin, 2 strains; threonine and glutamic acid, 1 strain; biotin, 2 strains; riboflavine, 1 strain; hypoxanthine, 2 strains.