Serologic confirmation of Neisseria gonorrhoeae by monoclonal antibody-based coagglutination procedures

Two commercially available monoclonal antibody coagglutination tests, Phadebact Monoclonal GC OMNI Test (PMGOT; Pharmacia Diagnostics AB, Uppsala, Sweden) and GonoGen (GG; New Horizons Diagnostics, Columbia, Md.), for the confirmation of Neisseria gonorrhoeae were evaluated. The sensitivities of PMGOT and GG were 99.2 and 98.7% and the specificities were 91.5 and 100.0%, respectively. False-positive reactions were observed with Neisseria lactamica and Neisseria meningitidis in PMGOT. A modification of the procedure recommended by the manufacturer for PMGOT was done by substituting Todd-Hewitt broth for 0.9% saline to prepare the suspension of the test organism. This eliminated technical difficulties with the test and resulted in a sensitivity and a specificity of 99.3 and 100.0%, respectively. Advantages offered by the modified PMGOT over GG were the better predictive value of the negative test, the lower cost, the ease of reading of the test, and the lack of noninterpretable results.