Tests that detect specific sequences of deoxyribonucleic acid (DNA) are now available to detect gonorrhoea, chlamydia and to a limited extent, other STIs.
These tests are nucleic acid amplification tests (NAAT), a generic term which includes polymerase chain reaction (PCR). The choice of test depends on the laboratory.
The NAAT process identifies DNA sequences found only in the organism being tested, making it a highly specific test. NAAT also amplifies very low amounts of DNA so that they are easily detected, making the technique highly sensitive. These two properties of the test make it much more accurate than the older technique of microscopy and culture. NAAT can identify chlamydia and gonorrhoea in a urine sample. As NAAT does not rely on live organisms it will also detect the DNA from dead organisms. Recently, studies have suggested that, in a woman, the sensitivity of NAAT testing in self-obtained vaginal swabs is better than that of urine, particularly for the detection of gonorrhoea. As a general rule in these guidelines we recommend the use of a self-obtained low vaginal swab (SOLVS) as the primary single specimen collection method of choice for women.
NAAT point-of-care testing using the GeneXpert test is available at health services in WA that have been selected to participate in a research project funded by the National Health and Medical Council Research Council.
Gonorrhoea culture is still required where there is urethral or cervical discharge. Current methods with NAAT do not allow antibiotic susceptibility testing and therefore, it is still important that, when patients present with a discharge, swabs are sent for culture.
NAAT may also be used to detect other STI pathogens, including herpes simplex virus (HSV), mycoplasma, ureaplasma, donovanosis, trichomoniasis and chancroid. Providers should discuss the appropriate testing options with their local laboratory service.