Comparisons of cost and accuracy of DNA probe test and culture for the detection of Neisseria gonorrhoeae in patients attending public sexually transmitted disease clinics in Los Angeles County.

BACKGROUND

Strict handling and transport requirements for the successful use of culture in the detection of Neisseria gonorrhoeae warrant investigation of accurate and cost-effective test alternatives such as the Gen-Probe PACE 2 DNA probe assay (Gen-Probe, Inc., San Diego, CA).

STUDY DESIGN

The Gen-Probe PACE 2 DNA probe assay for N. gonorrhoeae was compared with conventional culture methods in the principal Los Angeles County (LAC) Department of Health Services (DHS) Public Health Laboratory and three of its branch laboratories. Urethral and endocervical samples were collected from 1,566 patients (921 males; 645 females) attending six LAC DHS sexually transmitted disease clinics. Cost analysis was performed comparing material and labor costs of the two test methods.

RESULTS

The overall prevalence based on culture was 11.8% (15.7% for males; 6.4% for females). Nine samples were culture positive, Gen-Probe negative and four samples were culture negative, Gen-Probe positive and remained discordant after discrepant analysis. The sensitivity and specificity were 94.6% and 99.7%, respectively, for the PACE 2 assay compared with culture. The positive and negative predictive values were 97.8% and 99.3%, respectively. No statistically significant difference was found between the two tests. A cost analysis found an average cost of $3.11/test for culture and $3.85/test for PACE 2, given the approximate 12% disease prevalence in this population.

CONCLUSIONS

Gen-Probe's PACE 2 assay may provide an acceptable, cost-effective alternative to culture, especially among high-risk males.