Bactericidal and Opsonic Activity against Neisseria gonorrhoeae in Sera from Patients with Disseminated Gonococcal Infection

Bactericidal and opsonic actrvttres in convalescent-phase sera from patients with disseminated gonococcal infection (DCI) were analyzed with use of the patients' infecting strains and other strains of Neisseria gonorrhoeae</it>. Serum from a patient with C8 deficiency was opsonic for her first DCI isolate grown on solid medium or in chick embryos; with added complement the serum was bactericidal (at a dilution of 1:320). Her serum was not bactericidal for nine other isolates from patients with DCI. Only one of the other patients with DCI had detectable serum bactericidal activity (dilution, I :2.5) against her own isolate; this patient's serum was also active against one other DCI isolate. Opsonization was detectable only in sera that were potentially bactericidal and could be distinguished from bactericidal activity only with C8-deficient serum. The isolates from patients with DCI were of an auxotype different from that of most other gonococci, and most of the isolates tested were not killed by sera from patients with uncomplicated gonorrhea, even though these sera killed other gonococci. Thus, isolates from patients with DCI appeared to be significantly different from other gonococcal isolates.