Evaluation of an enzyme immunoassay and a modified coagglutination assay for typing gonococcal isolates with monoclonal antibodies.
In order to resolve methodologic and interpretation problems associated with the serotyping of Neisseria gonorrhoeae isolates with monoclonal antibodies specific for Protein I (PI) by coagglutination (the standard method; CoA1), two methods were compared with CoA1: an enzyme immunoassay (EIA) and a modified coagglutination assay (CoA2), in which methylene blue was added to the monoclonal antibody reagents. When the EIA was compared with the CoA1 method, 92.7% of the WI isolates were typed identically and 89% of the WII/III isolates were typed identically. When the CoA2 was compared with the CoA1 method, 92.7% of WI isolates were typed into similar serovars, in comparison to only 80.5% of the WII/III isolates. With the EIA method, only 21 of 328 isolates (6.4%) were retested because duplicate results were inconsistent, in comparison to 72 isolates (22%) with the CoA1 method and 120 isolates (36.6%) with the CoA2 method. In most cases result inconsistencies between duplicate tests were due to differences in reading weakly positive coagglutination reactions with single reagents (which on duplicate testing might be negative), the most notable being PIA reagent 4A12(b) and PIB reagents 1F5(b) and 2G2(g). The EIA method was the most reproducible method, and provides some degree of automation when serotyping large numbers of isolates.
Carballo
M
M
National Laboratory for Sexually Transmitted Diseases, Laboratory Centre for Disease Control, Ottawa, Ontario, Canada.
Dillon
J A
JA
D000372:Agglutination Tests; D000911:Antibodies, Monoclonal; D005069:Evaluation Studies as Topic; D005189:False Positive Reactions; D007124:Immunoenzyme Techniques; D009344:Neisseria gonorrhoeae / Q000145:classification*; D015203:Reproducibility of Results; D012703:Serotyping / Q000379:methods*
D000911:Antibodies, Monoclonal