Indole-positive strains of Klebsiella pneumoniae producing hydrogen sulfide in iron-agar slants

The biochemical characteristics of six strains of Klebsiella pneumoniae that produced H2S in TSI slants are described. All were biotypical except for the consistent characteristic of indole production. It is suggested that the qualities of H2S and indole production are linked biochemical features acquired by episomal transfer. The attention of bacteriology laboratory workers is directed to these strains, which are easily distinguished biochemically from other H2S-producing organisms by their otherwise biotypical pattern.