Susceptibility of Inbred Mice to Group A Streptococcal Infection. ∗

Summary

Less than 10 organisms of an unadapted strain of Streptococcus pyogenes, type 18, caused fulminant infection in BALB, BALB/c, AKR, DBA/2, C58 and C57 Black inbred mice. Pen bred Swiss albino mice were significantly more resistant to infection. Inbred BALB and C58 mice that survived the original inoculum underwent latent or chronic infection; organisms were recoverable from untreated mice for at least 3 to 4 months. Data were obtained which revealed that susceptibility of mice to infection depended on strain of serotype of the organism tested as well as the genetic constitution, age and sex of the host. These studies demonstrated that a spectrum of diseases could be produced by employing a single strain of Streptococcus pyogenes, type 18, and different strains of inbred mice. The application of these findings to study of streptococcal infections and their late sequelae was discussed.