The cervical lymph nodes in Streptococcus pyogenes, group A, type 50, infection in mice.

Streptococcus pyogenes, group A, type 50, one of the few group A streptococcal types naturally occuring in mice, proved highly virulent in this species after experimental infection. Intranasal infection of 96 mice (Swiss albino, NMRI, and CBA) with this microorganism induced profound reactions in the cervical lymph nodes of 69% of the animals. Histologically, two different forms of reaction were distinguishable. In 61 mice, the lymph nodes exhibited follicular and lymphoplasmacellular hyperplasia and in 9 animals suppurative lymphadenitis was present. The ability of type 50 streptococci to persist in the pharynx of mice, and the similarity of the morphological changes induced by this organism appear to make intranasal murine group A, type 50, streptococcal infection a suitable model for human streptococcal pharyngitis.