Comparison of GonoGen, GonoGen II, and MicroTrak direct fluorescent-antibody test with carbohydrate fermentation for confirmation of culture isolates of Neisseria gonorrhoeae

Abstract

When testing 248 clinical isolates of Neisseria gonorrhoeae, the sensitivity was 100% with GonoGen (Becton Dickinson Microbiology Systems), 99.6% (247 of 248) with GonoGen II (Becton Dickinson), 97.2% (241 of 248) with the MicroTrak direct fluorescent-antibody test (Syva), and 97.6% (242 of 248) with Rapid Fermentation Agar carbohydrates (Remel). Of 62 isolates of other Neisseria species, none was misidentified as N. gonorrhoeae by GonoGen, MicroTrak, or Rapid Fermentation Agar carbohydrates but 7 (31.8%) of 22 isolates of N. meningitidis gave strong, repeatedly false-positive results with GonoGen II. The sensitivity of all four assays was good to excellent, but all positive GonoGen II results should be confirmed with an independent assay, especially when isolates are recovered from sites where N. meningitidis is likely. Positive results from any of the assays should be routinely confirmed when dictated by specific clinical, legal, or microbiological circumstances.

Prevalence of fluorescent monoclonal antibody-nonreactive Neisseria gonorrhoeae in five North American sexually transmitted disease clinics

“…The present study validates reports of DFA-nonreactive gonococcal isolates among a small proportion of gonococci (2,8,9). In contrast to earlier reports, the present study of a systematic sample of gonococcal isolates from five cities indi-cates that the process is present only sporadically and that local laboratory use of monoclonal antibody reagents does not appear to be related to the increased prevalence of fluorescentantibody-nonreactive gonococci.…”

“…Commercially available direct fluorescent monoclonal antibody (DFA) reagents for identifying possible N. gonorrhoeae isolates from culture provides an easy, rapid means for the confirmatory identification of the organism (6,9). Several reports however, have described the failure of DFA reagents at detecting a small proportion of gonococci studied (1,2,8). To further evaluate the prevalence of N. gonorrhoeae isolates that are nonreactive but that react with commercially available DFA reagents, we evaluated a systematically collected sample of 556 presumptive N. gonorrhoeae isolates from sexually transmitted disease clinics in five cities participating in the Centers for Disease Control and Prevention-sponsored Gonococcal Isolate Surveillance Project (GISP) (7).…”