Fluorescent antibody test for the serological diagnosis of gonorrhea

Application of immuno-blotting to the differentiation of specific antibodies in gonorrhoea

The technique of immuno-blotting was used to examine the specificity of serum antibodies in patients with gonorrhoea and to define the significant antigenic determinant present in the desoxycholate extracts of gonococcal cell walls used previously for serological diagnosis. IgG but not IgA antibody was directed predominantly against lipopolysaccharide. Antibodies to outer membrane proteins were not found as frequently as expected. There was a suggestion from the results that antibodies to antigen PI was more common in systemic than in local infections.

Radioimmunoassay for detection of antibodies to Neisseria gonorrhoeae

A radioimmunoassay has been developed and evaluated for the serological diagnosis of gonorrhea. Purified gonococcal antigen was obtained from a culture of Neisseria gonorrhoeae (B370) and labeled with 125I for use in a double-antibody test system. The test was evaluated in populations segregated by sex and risk. The specificity of the assay in females was 90.2% (55/61) in low risk, 82.2% (2,245/ 2,732) in medium risk, and 54.1% (335/619) in high risk. The sensitivity was 69% (20/29) in medium risk and 78.3% (288/367) in high risk. In males, test specificity was 92.3% (24/26) in low risk and 50% (48/96) in high risk. The sensitivity was 70.8% (143/202) in the high-risk group. The data in this study indicate that this assay should not be employed for screening of either high- or medium-risk populations.

Enzymatic detection of Neisseria gonorrhoeae

In a study using a non-serological enzymatic approach for the detection of Neisseria gonorrhoeae in cervical and urethral swabs, the technique was shown to be technically feasible. The enzyme, 1, 2-propanediol oxidoreductase, was used as a presumptive diagnostic marker for N gonorrhoeae. Enzymatic activity was measured with a fluorometer. Two assay procedures were performed: (a) enzyme detection (two-tube and three-tube assays) requiring 60 minutes; and (b) enzyme inhibition (EI) (90-minute and modified 20-minute assays). Sensitivities of the two-tube, three-tube, and the 90-minute EI assays with male urethral specimens from a high-prevalence population were 80%, 84%, and 91% respectively. The specificities of these assays in a low-prevalence male population were not determined. Sensitivity of the 90-minute EI assay in a high-prevalence female group was 77% and specificity in a low-prevalence female group was 75%. The modified EI assay was tested only in a low-prevalence female group and had 87% specificity. Although the specificity of the assays needs improvement, several advantages--including early case detection, rapid availability of results, detection of current active infections, and the possibility of automation--are intrinsic in this enzymatic approach.

Serologic diagnosis of gonococcal infection

Infection with N. gonorrhoeae stimulates the production of antibodies to many common, species-specific, and type-specific antigens. The L-antigen is an envelop antigen and antibodies to it could be demonstrated by various methods in more than 90% of the patients after the first 10 days of infection. Serologic tests are not yet available in the United States. If and when they become available, they may be recommended for: (1) Screening asymptomatic men and women, (2) Use as an adjunct diagnostic tool in cases of prostatitis, arthritis, disseminated gonococcal infection, and pelvic inflammatory disease, (3) Use (alone or in conjunction with culture) when specimens must be mailed to a central laboratory, when mailing conditions do not allow for incubation within 24-48 hr, or when proper media and qualified bacteriologists are not available.

Classes of antibodies in acute gonorrhoea

In patients with acute gonorrhoea the antibody responses to envelope antigens of Neisseria gonorrhoea were investigated with a sensitive enzyme-linked immunosorbent assay. IgG antibodies predominated even early in the disease but IgM and IgA antibodies were present. Surprisingly there were circulating antibodies linked to secretory piece. These were largely but not entirely IgA and were presumed to have been absorbed from sites of local production.

Serum immunoglobulin response in uncomplicated gonorrhoea

Sera from 225 men and 140 women were examined by an indirect immunofluorescent antibody technique for antibody reactive with Neisseria gonorrhoeae. Antigonococcal IgM was demonstrated at a titre of greater than or equal to 16 in about 45% of infected, but in only 3% of non-infected, patients. Most of this antibody occurred in sera of patients who had been infected for less than 14 days. Antibody of the IgA class was found at a titre of greater than or equal to 16 in over half the infected, but in none of the non-infected, patients. IgG antibody reactive with the gonococcus was found in each infected patient at a titre of greater than or equal to 16 but in only 8% of controls. The mean log titre of this antibody was significantly higher in patients who had been infected for more than seven days than in those whose infection was of shorter duration.

The biology of the gonococcus

Gonorrhea has been known since antiquity. Today, this disease is the most commonly reported infectious disease in the U.S. The natural environment of the etiological agent, Neisseria gonorrhoeae, is man. In this host, the organism usually parasitizes mucosal surfaces populated by columnar epithelial cells. Under certain conditions, the gonococcus may disseminate or spread to adjacent organs. The gonococcus is well adapted to its environment and is a successful parasite. Until recently, gonococci were uniformly sensitive to penicilin. However, a plasmid encoding beta-lactamase has been identified in some isolates. Most strains exhibit specific requirements for various amino acids, vitamins, purines, and pyrimidines. Only glucose, pyruvate, and lactate are utilized as sources of energy. Glucose is dissimilated by a combination of the Entner-Doudoroff and pentose phosphate pathways. A tricarboxylic acid cycle is also present and active under certain conditions. Structurally, the cell envelope of the gonococcus resembles that of a typical Gram-negative bacterium. Gonococci are highly autolytic, especially in older cultures or after depletion of the energy source. Autolysis is not due solely to peptidoglycan hydrolysis, but appears to involve a destabilization of the outer membrane as well. Cell surface components such as pili, lipopolysaccharide, outer membrane proteins, and a capsule are associated with the virulence and pathogenicity of this organism.

Purification of Neisseria gonorrhoeae surface L-antigen

A purified preparation of the L-antigen of Neisseria gonorrhoeae with a 40-fold increase of antigenic activity over the crude extract was prepared. The antigen was extracted from the cell envelope by mild treatment with sodium dodecyl sulfate and purified by Sepharose 4B, diethylaminoethyl-cellulose, and diethyl-(2-hydroxypropyl)aminoethyl (QAE)-Sephadex column chromatography. The purified antigen was heat labile and trypsin sensitive. The smallest antigenically active subunit appeared to have a molecular weight of 38,500, as shown by polyacrylamide gel electrophoresis of the product incubated with sodium dodecyl sulfate.

Modified indirect fluorescent-antibody test for aspergillosis

Diffuse fluorescence in an indirect fluorescent-antibody test for antibody to Aspergillus fumigatus was eliminated by using germlings, rather than hyphae, as antigen. The modified method yielded diagnostic titers larger than or equal to 1:32 in 24 of 25 known cases, was highly specific, and showed good correlation with clinical status and results of immunodiffusion. This technique, which uses the germling antigen, inactivation of test serum at 59 +/- 1 degrees C, and anti-immunoglobulin G conjugate, is a sensitive, specific, and reliable quantitative indicator of aspergillosis and is useful in following the course of the disease.

Evaluation of the fluorescent gonococcal test-heated

In a 1-year evaluation of the indirect fluorescent antibody test for gonorrhea, 16,127 specimens from low-and high-risk groups were examined, and the results were compared with culture, history of exposure to a known patient, and clinical signs and symptoms. The results confirmed the usefulness of the indirect fluorescent antibody test for gonorrhea as a screening procedure, especially for women in the low-risk group. The test is more economic and probably more sensitive than culture for mass screening of asymptomatic women.