VIRULENCE IN LEPTOSPIRAE

Abstract

Avirulent strains of L ictero-haemorrhagiae were susceptible to physiological concentrations of NaCl in culture media at 37[degree]C but not at 30[degree]C. Virulent strains grew normally at 37[degree]C in media with NaCl or in serum from infected guinea pigs. At 40[degree]C, virulent strains grew slowly in Korthof medium but not in media with NaCl. Avirulent strains failed to survive in Korthof medium at 40[degree]C. The relative resistance of virulent Leptospirae to conditions resembling those in vivo could explain their survival in infected animals.