Identification of problem Neisseria gonorrhoeae cultures by standard and experimental tests

Abstract

Standard and experimental tests were used by a reference diagnostic laboratory to determine the identity of 182 "suspected" Neisseria gonorrhoeae isolates submitted by state health departments because of inconclusive laboratory results. More than 97% of these cultures were subsequently identified by a rapid microcarbohydrate test in conjunction with confirmatory immunological procedures. The experimental rapid slide agglutination test using rough-lipopolysaccharide antibody, the Phadebact co-agglutination test, and fluorescent antibody test identified 49.3 to 94.1% of these cultures. Because of frequent problems with carbohydrate utilization, Neisseria meningitidis and Branhamella catarrhalis were the two microorganisms most often confused with N. gonorrhoeae by submitting laboratories.

Rapid confirmatory identification of Neisseria gonorrhoeae with lectins and chromogenic substrates

“…In the cystine tryptic agar method, incubation and growth of the organism for 24 to 48 h is required before acid production can be detected (11,13,17). The reported reliability of the cystine tryptic agar method for the identification of N. gonorrhoeae ranges from 73.1 to 98.6% (1,12,16). In one study, 21 of 78 isolates of N. gonorrhoeae failed to grow in unsupplemented cystine tryptic agar medium (12).…”

Evaluation of the RIM-N, Gonochek II, and Phadebact systems for the identification of pathogenic Neisseria spp. and Branhamella catarrhalis

“…Since multiply auxotrophic gonococci may present difficulties in identification by conventional test methods (2,8,9), a collection of prototrophic and auxotrophic strains having single and multiple nutritional requirements for growth were tested on each of the identification systems ( Table 4). The RIM-N identified 95% of the strains requiring arginine-hypoxanthine-uracil (AHU) for growth and 100% of the non-AHU-requiring strains; 100% of the strains in both groups were correctly identified by the GCII system.…”

“…If the suspension is colorless at the end of the incubation period, the paired stopper is split apart and the topmost stopper is inserted into the tube. The tube is then inverted so that the bacterial suspension comes in contact with the diazo dye coupler The Phadebact Gonococcus test is a COA test for the identification of N. gonorrhoeae (1,2,8). This test was performed from primary MTM or CH agar subcultures by the boiled bacterial suspension technique recommended by the manufacturer.…”

“…isolated from clinical specimens include conventional and modified carbohydrate degradation procedures, enzymatic tests with chromogenic substrates, and immunologic coagglutination (COA) tests for confirmation of Neisseria gonorrhoeae. Whereas conventional sugar utilization tests may require prolonged incubation for organism growth and test results, the modified procedures rely on a heavy bacterial inoculum for rapid identification (2,6,8). Chromogenic enzyme substrate tests, in combination with certain modified conventional tests, have also proven useful for identification of Neisseria spp.…”

“…and other bacteria, and commercial systems in which this method is used generally provide results in 4 h (3,5,10). In COA test methods, antibody directed against gonococcal antigens is utilized to produce specific agglutination reactions, allowing rapid confirmation of N. gonorrhoeae (1,2,7). Although not currently commercially available, specific agglutination of N. gonorrhoeae by lectins has also been proposed as a useful test for confirmatory identification of gonococci (4).…”