Host-parasite Relationships among Group a Streptococci. Ii. Influence of Sex on the Susceptibility of Inbred Mice toward Streptococcal Infection.

Willoughby, Donald S. (University of Minnesota, Minneapolis), and Dennis W. Watson. Host-parasite relationships among group A streptococci. II. Influence of sex on the susceptibility of inbred mice toward streptococcal infection. J. Bacteriol. 87:1457-1461. 1964-BALB/Sy mice showed marked sex differences in susceptibility to a strain of Streptococcus pyogenes type 18. Castration of the highly susceptible normal adult male increased their resistance 1,000-fold, which approximated that of normal female mice. Treatment of male mice with estrogen and stilbestrol did not affect their resistance significantly. Young, sexually immature male mice, 4 weeks old, were more resistant than mature males. Susceptibility of the resistant females was not affected by age or bilateral ovariectomy, but testosterone injections caused an increase in susceptibility. Treatment of male mice with estrogen and stilbestrol did not modify their resistance. Smears of peritoneal exudates from normal male mice after intraperitoneal injection of streptococci revealed rapid multiplication of the organisms. There was no evidence of multiplication in the resistant normal female and castrated male mice.