BD ProbeTec ET assay for the diagnosis of gonorrhoea in a high-risk population: a protocol for replacing traditional microscopy and culture techniques.
OBJECTIVES: To evaluate the Neisseria gonorrhoeae Becton Dickinson (BD) ProbeTec strand displacement assay (SDA) on female endocervical swab and male first void urine against culture for Neisseria gonorrhoeae on female endocervical and urethral swab for the diagnosis of N gonorrhoeae infection in genitourinary medicine (GUM) attendees. To determine an algorithm for implementation of N gonorrhoeae infection screening by SDA in these patients taking account of the desirability of having a N gonorrhoeae isolate in people with N gonorrhoeae infection. METHODS: Initially, 1582 patients attending the GUM clinic were tested for N gonorrhoeae infection by SDA and routine microscopy, and culture. On the basis of the results, a protocol for diagnosis of N gonorrhoeae infection by SDA, with culture specimens only from patients with a listed risk factor for acquiring N gonorrhoeae infection, was devised and implemented. A post implementation audit was done to assess the effectiveness of this protocol for routine service use. RESULTS: There was good concurrence between the N gonorrhoeae SDA and culture results with a N gonorrhoeae infection prevalence rate of 3.4% by both methods. All men and 85% of women with N gonorrhoeae infection had an identifiable risk factor for acquiring infection. Overall, 38% men and 60% women attending the GUM clinic had this listed risk factor for acquiring N gonorrhoeae. Post implementation audit confirmed the initial findings. CONCLUSION: Nucleic acid amplification techniques like the SDA are sensitive and specific for diagnosis of N gonorrhoeae. We were able to list certain risk factors, which were predictive of those patients most likely to have N gonorrhoeae infection. To obtain timely sensitivity data, a culture specimen should also be submitted at the same time from patients deemed to have a listed risk factor for acquiring Neisseria gonorrhoeae infection.