Background:
Testing methodologies for Chlamydia trachomatis and Neisseria gonorrhoeae have become more accurate with the implementation of nucleic acid amplified assays (NAAT). In addition to the increased sensitivity of the tests, manufacturers have also included the option of testing urine and self-collected vaginal swabs, which are easier to collect than endocervical and urethral swab specimens.


Objective:
Michigan Department of Community Health (MDCH), compared two NAATs, APTIMA by Genprobe and ProbeTec ET by Becton Dickinson, to find which test was most sensitive and specific for our population.


Method:
A total of 139 urines, 199 paired endocervical swabs, 99 paired urethral swabs, and 199 self-collected vaginal swabs were tested with APTIMA and ProbeTec. Thirty-seven urine samples in DNA/RNA Protect (Sierra Diagnostics) transport system were also retested with APTIMA reagents after being held for 6 days at room temperature to validate the ability to test specimens collected with our current transport system.


Result:
APTIMA demonstrated increased sensitivity and specificity for detecting CT and GC in urine, urethral and endocervical swab specimens (98.6%, 99.1%. 96.5%, 99.7%, respectively) compared to ProbeTec (84%, 100%, 92.9%, 99.7%, respectively). ProbeTec swab specimens were found to be suitable with APTIMA reagents. Self-collected vaginal swabs were validated as an acceptable source for testing. Urines collected with the DNA/RNA Protect transport system cannot be tested using APTIMA reagents.

Conclusion:
APTIMA offers several advantages over ProbeTec including increased sensitivity and specificity; longer specimen out date (30 days urine and 60 days swab, for APTIMA versus 6 days for ProbeTec); the ability to test self-collected vaginal swabs; and decreased sample processing for urine specimens.


Implications:
APTIMA offers sufficient increased sensitivity and specificity over ProbeTec, particularly for urine specimens, to make it worthwhile for MDCH to change testing platforms. APTIMA has the additional advantage of offering self-collected vaginal swabs that is useful in some populations.