Non-radioactive DNA probe to identify Neisseria gonorrhoeae

Comparative evaluation of AccuProbe culture identification test for Neisseria gonorrhoeae and other rapid methods

The AccuProbe chemiluminescent culture identification test for Neisseria gonorrhoeae (Gen-Probe Inc., San Diego, Calif.) was assessed in a comparative evaluation with other rapid methods by using 269 isolates of oxidase-positive, gram-negative diplococci. Chemiluminescence was read with a PAL luminometer, and results were expressed as PAL light units (PLUs): the cutoff value for a positive identification was 1,500 PLUs. All 200 isolates of gonococci confirmed by carbohydrate utilization and serotyped with monoclonal antibodies were identified correctly by AccuProbe on initial testing. The API Quadferm system (Bio Merieux, Marcy l'Etoile, France) identified 95% (n = 190) of the gonococci correctly on initial testing and 99.5% (n = 199) on repeat testing, while the Phadebact Monoclonal GC test (Kara Bio Diagnostics AB, Huddinge, Sweden) identified 95.5% (n = 191) of the gonococci on both initial and repeat testing; 8 of the Phadebact-negative isolates were all of the same rare serovar (serovar 1B-17). The mean PLU for the gonococcal isolates was 9,014 (range 2,264 to 10,845) compared with a mean of 51 (range, 8 to 109) for the 69 nongonococcal isolates. We conclude that the AccuProbe culture confirmation test provides a rapid and accurate objective means of identifying cultured N. gonorrhoeae isolates.

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.