Evaluation of a ten-minute chromogenic substrate test for identification of pathogenicNeisseria species andBranhamella catarrhalis

Abstract

A ten-minute chromogenic substrate test was evaluated for its ability to rapidly identify pathogenic Neisseria spp. and Branhamella catarrhalis. Identifications obtained with this system were compared to those obtained using conventional procedures. The test correctly identified 98.9% of 90 Neisseria gonorrhoeae, 98.3% of 60 Neisseria meningitidis, 96.2% of 26 Neisseria lactamica, and 100% of 36 Branhamella catarrhalis strains. Eight Neisseria subflava strains that grew on modified Thayer-Martin agar were prolyl aminopeptidase positive and were misidentified as Neisseria gonorrhoeae. Other strains of saprophytic Neisseria spp. also reacted with the chromogenic substrates. The system was accurate and reliable for identifying the commonly encountered pathogenic species. In light of recent reports describing new species and atypical Neisseria strains, however, careful attention to the salient features of both common and atypical organisms is necessary for proper use of rapid enzymatic identification tests.

Superoxol and aminopeptidase tests for identification of pathogenicNeisseria species andMoraxella (Branhamella) catarrhalis

“…A heavy suspension of the culture to be tested (at least a no. Some authors, however, have reported positive results with strains of Neisseria subflava, Neisseria mucosa and Neisseria sicca (17,18,21), as occurred with two strains in this study. A tablet of either PAP or GAP was added to each tube, and the tube incubated at 35 °C for 4 h. The end-points were read after adding two drops (16)(17)(18)(19).…”

Identification of Neisseria gonorrhoeae using the Neisstrip rapid enzyme detection test.

“…8 The superoxol test requires experience to differentiate positive and negative results but gave results consistent with Neisstrip and with Phadebact Monoclonal GC in 98% of organisms tested in the prospective study. It is rapid, and cheap, but shows some positive results with other Neisseriaceae, particularly N lactamica, N meningitidis, and B catarrhalis.5 Nongonococcal isolates from gonococcal selective medium, when tested by the superoxol test and Neisstrip, gave a false positive rate which we estimate to be less than 0 1%.…”

Rapid identification of pathogenic neisserias using the Identicult-Neisseria test

“…mentngitidis that gave a weak reaction for GAP and one strain of N. meningitidis that gave no reaction for GAP; all three strains, however, gave positive reactions for PAP. Janda and Sobieski (1988) reported that the Identicult-Neisseria test correctly identified 98.9% of 90 N. gonorrhoeae strains, 98.3% of 60 N. meningitidis strains, 96.2% of 26 N . lactamica strains and 100% of 36 M o r .…”

“…grown on selective medium. If non-selective medium is used, non-pathogenic neisseria such as N. subJava may grow leading to misidentifications (Dillon et al 1988;Janda and Sobieski 1988). Depending on the sample site and sexual orientation of the patient isolation of non-gonococcal neisseria may vary from 0.4 to 11.4% (Young and Reid 1987).…”