Comparative Efficiency of Plating Media for the Isolation of Shigella Dysenteriae

Abstract

This is a report of routine platings for members of the Shigella group to compare the efficiency of desoxycholate-citrate, plain Endo, LiCl Endo, and Bi sulfite agars as selective media. Of 435 positive isolations on 1 or more of the 4 media desoxy. showed 95% positive, plain Endo showed 48%, LiCl Endo 20%, and Bi sulfite showed 2.4%. 175 specimens would have been reported negative if desoxy. had not been used. Further positives were reported by repeated platings of refrigerator preserved specimens. In another series of 1,062 platings Shigella-Salmonella agar (Difco) compared favorably (379 pos. isolations) with desoxy. (356 pos. isolations).