Neisseria gonorrhoeae. II. Colonial variation and pathogenicity during 35 months in vitro.

During 35 months of selective in vitro cultivation, Neisseria gonorrhoeae cells retained their virulence for humans and were shown to be closely related to a particular colonial morphology. Saline-autoagglutinability was the only other characteristic distinguishing virulent from avirulent cells. Human responses to challenge with cells of the different colonial types were studied for their relationships to virulence or avirulence.