Use of the antiserum-agar plate technique for specific identification and isolation of Pasteurella pestis.

Pasteurella pestis colonies were specifically identified on antiserum-agar plates used for primary culture of tissues from experimentally infected guinea pigs. Both selective and nonselective antiserum-agar plates were used to identify P. pestis from guinea pigs kept at 22 C for periods up to 4 days after death from plague. Colonies identified as P. pestis on selective and nonselective antiserum-agar plates, by the appearance of precipitin rings following brief chloroform vapor treatment, remained viable and were subsequently purified on nonselective antiserum-agar plates. Isolates obtained in this manner were uniformly lethal when injected into mice and guinea pigs, and conformed to standard laboratory criteria for P. pestis. P. pestis was identified on selective antiserum-agar plates from the spleens of all guinea pigs killed by the isolates, and from a large majority of the mice. The practical value and confirmative nature of the method were demonstrated.