The applicability of the precipitin reaction in determining the infectivity of discharges from gonorrheal infections

Abstract

The demonstration of gonococci by either culture or smear method is difficult after the subsidence of acute gonorrheal symptoms. Complement fixation tests on the blood of treated or untreated cases may give negative results. There is need therefore of a method to determine the persistence of infectiousness.

Robinson and Meader 1 reported encouraging results with the application of the precipitin reaction to discharges of gonorrheal origin. We have attempted to verify their results, working under a grant from the U. S. Interdepartmental Social Hygiene Board.

Selected rabbits were immunized with live gonococci to produce the immune serum used for the tests. Specific gonococcus antigen was prepared by autolyzing the gonococcus in salt solution for several days and centrifugalizing to obtain a clear antigen.

“Discharge extracts” from cases were prepared by adding to 2 c.c. of salt solution the secretions obtained from the cervix or vagina. The mixture was allowed to stand over night and then centrifugalized until clear. 0.2 c.c. of clarified extract was then added to 0.2 c.c. of diluted immune serum and to 0.2 c.c. of diluted normal serum as a control. A positive result was shown by the development of a ring of varying thickness and opacity at the point of contact of extract and serum or by the development of a precipitate. The reaction appeared usually from two hours to eighteen hours.

With 92 specimens, smears positive, 82 per cent. gave reactions with gonococcus serum while 21 per cent. gave reactions with normal serum. With 49 specimens, smears negative, 61 per cent. gave reactions with gonococcus serum, while 51 per cent. gave reactions with normal serum. The relatively frequent reactions with normal serum indicated the presence of a non-specific factor and raised the question as to whether the reactions occurring with immune serum alone could be considered specific.

Of 17 non-gonorrheal vaginal specimens from children 100 per cent. reacted with immune serum and 94 per cent. with normal serum.