IDENTIFICATION OF NEISSERIA GONORRHOEAE IN CULTURES FROM TONSILLO-PHARYNGEAL SPECIMENS BY MEANS OF A SLIDE CO-AGGLUTINATION TEST (PHADEBACT® GONOCOCCUS TEST)

Abstract

A slide co-agglutination test (Phadebact Gonococcus Test) for the serological identification of N. gonorrhoeae was assessed on gonococcal-like, oxidase positive colonies from 120 cultures originating from about 6500 consecutive [human] tonsillo-pharyngeal specimens received at the Neisseria Department, Statens Seruminstitut, Copenhagen, Denmark. The test was performed after subculture on a serum-free medium, since this procedure reduces the number of strains showing inconclusive reactions (pseudo co-agglutination). If pseudo co-agglutination does occur, the test can be repeated with the addition of trypsin to the test system. This causes the previously inconclusive reactions to be reverted to clearly positive rections in the case of gonococci, and to clearly negative reactions in more than half of the previously inconclusive reactions with other bacterial strains. The results obtained by the Phadebact Gonococcus Test were compared with those obtained by bacteriological identification procedures. Of the 120 cultures examined, 56 contained gonococci, and all strains were identified by the slide co-agglutination test (5 strains with the addition of trypsin). The remaining 64 cultures were negative or exhibited consistently pseudo co-agglutination (8 strains). The specificity and sensitivity of the reagent was further confirmed by the examination of 53 strains of N. gonorrhoeae and 50 strains representing Neisseria spp. commonly occurring in tonsillo-pharyngeal specimens. The Phadebact Gonococcus Test was considered to be a reliable alternative to routine bacteriological identification of N. gonorrhoeae.