Evaluation of a gonococcal serologic test

Abstract

The fluorescent gonorrhea test--heated (FGT-H), an indirect immunofluorescent method for detecting the presence of antigonococcal antibodies in serum, was evaluated in 1,000 women referred to a private clinic for the termination of pregnancy, 202 women treated at a municipal venereal disease clinic, and six women hospitalized with gonococcal bacteremia. The test was positive for 17.7% of private outpatients, even though gonococci were cultured from only 1.1% of these women, and another 5.1% had histories of gonococcal infection. Positive test results were found for 68.3% of the women in the venereal disease clinic population, in which the prevalence of gonococcal infection was 36.1% and an additional 25.2% had had gonorrhea previously. The test was positive for all six patients with gonococcemia. The sensitivity of the test in the low-risk population was 72.7%, which was not significantly different from the sensitivity of 84% in the high-risk population. Specificity of the test was 83% in low-risk patients, but only 41% in high-risk patients. These findings indicate that a negative test is a highly reliable means for excluding gonorrhea in populations of low-risk women. The predictive value of a positive test is low, ranging from 4.5% in the low-risk group to 45% in the high-risk group.