Evaluation of Gonozyme, an enzyme immunoassay for the rapid diagnosis of gonorrhea

Comparison of Gram stain with DNA probe for detection of Neisseria gonorrhoeae in urethras of symptomatic males

The comparison of Gram-stained urethral smears with Gen-Probe for the detection of Neisseria Gonorrhoeae in the urethras of males with symptomatic urethritis revealed a 99.6% correlation between the two methods. A simple Gram stain would appear to be the method of choice for the detection of gonorrhea in symptomatic males, because it is much less expensive and much more rapid than the Gen-Probe method.

Urethritis caused by neisseria meningitidis: a case report

Isolation of N. meningitidis from the male urethra has become more common in recent years and this has been attributed to sexual activities and changes in social attitudes. We describe a further case of acute urethritis caused by transmission of N. meningitidis occurring after a single sexual contact (fellatio) in a heterosexual man. The urethritis was initially diagnosed as being caused by N. gonorrhoeae on a presumptive basis, then attributed to N. meningitidis serogroup Y. This case shows the need of accurate diagnostic procedures in all cases resembling gonococcal urethritis.

Laboratory methods in genitourinary medicine. Methods of diagnosing gonorrhoea

Gonorrhoea is normally diagnosed presumptively by the presence of intracellular Gram-negative cocci on a Gram stain and confirmed by culture of the causative organism, Neisseria gonorrhoeae. Alternative methods have been evaluated extensively for the detection of gonococci in clinical specimens including immunological techniques such as ELISA and immunofluorescence, DNA probes, genetic transformation and the limulus lysate assay. Some of these tests have proved as sensitive and specific for the detection of gonorrhoea in symptomatic men as the Gram stain but offer no advantage in time or cost. In women, no test has been found that shows a sensitivity and specificity sufficiently adequate for clinical use. Culture in men and women remains the method of choice for diagnosis. In addition the need to obtain the infecting organism for antibiotic susceptibility testing has not been overcome. In contrast, the rapid identification of N gonorrhoeae can be achieved within four hours using either monoclonal antibodies or by the detection of preformed enzymes. New methods for both the detection and identification of N gonorrhoeae should be carefully evaluated particularly for use in cases of child and sexual abuse where medico-legal problems may arise.

Rapid diagnosis of common sexually transmitted diseases in adolescents: a review

Sexually transmitted diseases (STDs) represent a significant health problem for adolescents in the United States. As a result, clinicians from a number of disciplines, among them pediatrics and dermatology, may be called on to evaluate teenage patients with these infections. Traditionally, the diagnosis of many STDs has relied on isolation of the causative organisms in culture. While such procedures typically offer optimal diagnostic accuracy, they are often time consuming and expensive, and may not be widely available. In an attempt to remedy this, culture-independent techniques have been developed to permit more rapid and economical diagnosis of these important pathogens. The strengths and limitations of these methods must be understood, however, for the tests to be used effectively.

Clinical laboratory applications of monoclonal antibodies

Monoclonal antibody (MAb) technology is well recognized as a significant development for producing specific serologic reagents to a wide variety of antigens in unlimited amounts. These reagents have provided the means for developing a number of highly specific and reproducible immunological assays for rapid and accurate diagnosis of an extensive list of diseases, including infectious diseases. The impact that MAbs have had in characterizing infectious disease pathogens, as well as their current and future applications for use in clinical microbiology laboratories, is reviewed. In addition, the advantages (and disadvantages) of the use of MAbs in a number of immunoassays, such as particle agglutination, radioimmunoassays, enzyme-linked immunosorbent assays, immunofluorescent-antibody assays, and immunohistology, are explored, including the use of these reagents in novel test system assays. Also, nucleic acid probe technology is compared with the use of MAbs from the perspective of their respective applications in the diagnosis of infectious disease agents. There is no question that hybridoma technology has the potential to alter significantly the methods currently used in most clinical microbiology laboratories.

Neisseria gonorrhoeae: a versatile pathogen

Neisseria gonorrhoeae is one of the most important causes of sexually transmitted disease. We do not fully understand the pathogenesis of infection with this organism, although recent improvements in immunological and molecular techniques have brought us closer to an answer. These techniques are now also being used to detect and identify N gonorrhoeae and to analyse the epidemiology of gonorrhoea. Plasmid and chromosomal mediated antibiotic resistance increases the difficulty of controlling gonorrhoea. Resistant strains occur all over the world and new patterns of resistance are still emerging. A better understanding of gonococcal pathogenicity is necessary for the development of an effective vaccine. Despite work on pili and outer membrane proteins no vaccine yet exists. The control of gonorrhoea still depends on diagnosis, treatment, and epidemiological control, facilities that are not widely available in many of those parts of the world where gonorrhoea is a major problem.

Rapid detection methods in microbiology: are they right for your office?

This article discusses some of the direct test methods for diagnosing Group A streptococcal pharyngitis, urinary tract infection, and the three most common sexually transmitted diseases: gonorrhea, Chlamydia, and Herpes simplex virus infection. Emphasis is placed on their practicality for the office setting as well as the limitations of the test methods in various patient populations.

Diagnosis of Neisseria gonorrhoeae and Chlamydia trachomatis infections using antigen detection methods

Rapid antigen detection methods have great potential value in managing sexually transmitted gonococcal and chlamydial infections. Ideally, such tests should be rapid, technically simple, inexpensive, accurate, and applicable to all sites of infection commonly sampled (cervix, urethra, pharynx). For gonorrhea, the Gram stain fulfills these criteria in men with symptomatic urethritis, but lacks sensitivity when used at other sites or in asymptomatic patients. Antigen detection for gonorrhea would thus be of greatest value in 1) the diagnosis of gonococcal cervical infections in women with mucopurulent cervicitis or pelvic inflammatory disease, 2) the diagnosis of gonococcal proctitis in homosexual men, and 3) in situations requiring lengthy specimen transport. Because culture confirmation of Chlamydia trachomatis infections is not widely available, antigen detection tests could be of great value in management of these infections. Major uses include 1) confirming infection in women with cervicitis, endometritis, and pelvic inflammatory disease; 2) screening for asymptomatic infections in high risk groups of women; and 3) confirmation of Chlamydia trachomatis infections in infants and in adult males. The currently available methods for diagnosis of gonococcal and chlamydial infection by antigen detection are reviewed herein. Continued experience with antigen detection tests in well defined populations having high and low risk of gonococcal and chlamydial infection is needed to more fully determine how best to utilize these assays.

Enzyme-linked immunoassays for the detection of microbial antigens and their antibodies

Antibodies could be labeled with enzymes for use in histochemical staining procedures by enzyme-immunoassay (EIA). The use of EIA is an extension of previously used serological tests, using enzyme-labeled antibody or antigen to determine antibody content. Direct detection of antigen by EIA represents a more dramatic departure from previous methods based on culture. Also, the method has enabled detection of infectious agents that are difficult to cultivate, such as hepatitis A virus and rotavirus, or agents that cannot be cultivated, such as hepatitis B. The use of EIA tests for detection of microbial antigens provides an alternative to culture as a means for direct identification of a specific microbial agent. It also provides a means to detect microbial agents which have not been successfully propagated. The detection of circulating antigen or detection of antigen in other body fluids by EIA is more difficult than detection of antibody because of the sensitivity required, and because of interfering substances in specimens such as feces and respiratory secretions. For this reason, very few antigen detection assays have the sensitivity and specificity required to be used as a primary diagnostic test. The number of tests that have been developed, however, is impressive and because of the possibilities for rapid, specific diagnosis, the interest in antigen detection by EIA remains high.

Evaluation of a direct immunofluorescence test for diagnosing gonorrhoea

A new direct immunofluorescence reagent (Syva and Genetic Systems Inc) was evaluated for its ability to detect Neisseria gonorrhoeae in specimens from populations with a high prevalence of the infection. Gonorrhoea was diagnosed by culture in 45 of 105 (43%) urethral specimens from men and 17 of 90 (28%) urethral and 25 of 60 (42%) cervical specimens from women. In men the immunofluorescence test had a sensitivity of 84.4% and a specificity of 100%; Gram staining gave values of 94% and 100%, respectively. The sensitivity of the immunofluorescence test could be increased to 89% by testing duplicate smears. In women the immunofluorescence test had a sensitivity of 65% and a specificity of 98% for urethral samples and values of 72% and 94%, respectively for cervical samples. At both sites the sensitivity of the Gram stain was 40% and the specificity 100%. The testing of duplicate immunofluorescence smears increased the sensitivity to 76% for urethral and 88% for cervical samples.