Gonococci in Urethral Exudates possess a Virulence Factor lost on Subculture

Abstract

MAN is uniquely susceptible to gonorrhoea, but antibodies present in normal human sera are bactericidal for cultured gonococci^1–3. The ineffectiveness of these antibodies in the natural infection may be explained if gonococci growing in the host possess a factor, perhaps a surface antigen, which protects the organism from the bactericidal action of serum. There is some evidence that Neisseria gonorrhoeae loses virulence factors during growth in vitro because enormous doses of cultured gonococci were required to infect volunteers^4,5 while organisms recovered from the resulting urethral discharges exhibited enhanced virulence⁶. Another, less likely, suggestion is that gonococci only infect individuals lacking bactericidal antibodies to the strain concerned. To distinguish between these possibilities we have tested the ability of serum from men with gonorrhoea of less than 3 days duration to kill the gonococci present in the urethral exudate and the same organism after subculture.