Comparative Evaluation of Five Commercial Systems for the Rapid Identification of Pathogenic Neisseria Species

Prompt diagnosis and effective treatment of urogenital gonococcal infections require rapid isolation and identification of Neisseria gonorrhoeae from urogenital specimens. We evaluated a new, rapid (30-min) test called Gonochek II (E-Y Laboratories, San Mateo, Calif.) which utilizes chromogenic substrates for the identification of pathogenic Neisseria species. It was compared with the API NeIdent (Analytab Products, Inc., Plainview, N.Y.), Minitek (BBL Microbiology Systems, Cockeysville, Md.), and RapID NH (Innovative Diagnostics, Atlanta, Ga.), systems and the Phadebact GC (Pharmacia Diagnostics, Piscataway, N.J.) test for its performance in identifying known strains of N. gonorrhoeae (39 strains), Neisseria meningitidis (22 strains), Neisseria lactamica (12 strains), and Branhamella catarrhalis (17 strains). The Gonochek II system correctly identified 100% of N. gonorrhoeae, N. lactamica, and B. catarrhalis strains and 95.4% of N. meningitidis strains. The percent agreement for correct identification of all strains tested was 98.8%. In contrast, the Minitek, RapID NH, and API NeIdent systems correctly identified 86.6, 80.0, and 73.3% of the strains, respectively. The Phadebact GC test identified 94.9% of the N. gonorrhoeae isolates but also cross-reacted with 41.6% of the N. lactamica strains. The Gonochek II system is rapid, simple to perform, and easy to interpret, requires 1 to 2 min to set up, and more accurately identifies pathogenic Neisseria species when compared with other systems used in this study.