Antigenic Similarity of Some Trained Resistant Strains of Viridans Streptococci to Streptococcus faecalis

Abstract

Seven strains of viridans streptococci were adapted to resistance to sulfathiazole, aureomycin, penicillin, and streptomycin. The parent and resistant strains were tested for their ability to react with antiserum produced against S. faecalis. Five of the parent strains, which were sensitive to sulfathiazole, did not react, but 2 with somewhat higher resistance did. All but one of the resistant strains were positive. This was a streptomycin resistant strain which had a lower resistance to sulfathiazole than the others. Viridans streptococci, when adapted to resistance to sulfathiazole, aureomycin, penicillin, and streptomycin, at the same time become highly resistant to sulfathiazole, and acquire not only biochemical properties similar to enterococci, but also acquire antigenic properties which enable them to react with an enterococcus.