Identification of Neisseria gonorrhoeae using the Neisstrip rapid enzyme detection test

A rapid enzyme activity strip test (Neisstrip, Lab M Ltd, Bury) was compared retrospectively with Phadebact Monoclonal GC coagglutination (Pharmacia Diagnostics, Uppsala, Sweden), cystine trypticase agar sugar utilisation (CTA), and Gonochek II (J W Turner, Liverpool) enzyme methods for identification of 95 Neisseria spp and related species. These had been previously identified using standard methods and included 29 that had given aberrant results. Neisstrip identified correctly all but two, including nine incorrectly identified by Phadebact and 18 erroneously identified using CTA sugars. Results were similar to those obtained with Gonochek II. After this a prospective study was performed testing 400 oxidase positive isolates derived from clinical samples cultured on gonococcal selective medium. Two organisms, both Moraxella spp, were incorrectly identified as N gonorrhoeae by the Neisstrip. The superoxol test, when used with either the Phadebact or Neisstrip tests, maintained 100% sensitivity and specificity. The Neisstrip is a rapid, economic test that is accurate and easy to interpret. It may be used alone or in conjunction with a superoxol test or a coagglutination test, which is relatively accurate but more expensive, and found by some technical staff to be more difficult to interpret.