Review of use of a new rapid real-time PCR, the Cepheid GeneXpert^® (Xpert) CT/NG assay, for Chlamydia trachomatis and Neisseria gonorrhoeae: results for patients while in a clinical setting

Abstract

Rapid diagnostics for Chlamydia trachomatis and Neisseria gonorrhoeae are desirable so that patients can be treated while they are still in the clinic or doctor’s office. The Cepheid GeneXpert^® (Xpert) CT/NG assay was US FDA-cleared in December 2012. The assay is a rapid real-time PCR nucleic acid amplified test. The cartridge-based assay detects DNA of Chlamydia trachomatis and Neisseria gonorrhoeae. It is FDA-cleared for use in female endocervical swabs, patient-collected vaginal swabs and for female and male urine specimens from symptomatic and asymptomatic patients. It has demonstrated near-perfect sensitivity and specificity in urogenital specimens. The Xpert is a modular platform for testing samples directly from patients, which requires no hands-on manipulation from specimen loading until results are available. Results are provided in approximately 90 minutes. It has been graded by the FDA as moderately complex for Clinical Laboratory Improvement Amendments. Several publications have reported its promising use in clinical settings.

Keywords::

• Cepheid GeneXpert^®
• Chlamydia trachomatis
• Neisseria gonorrhoeae
• ocular samples
• point of care
• rapid real-time PCR
• rectal samples

Financial & competing interests disclosure

The author has received prior research support and lecture honoraria from Cepheid and Gen-Probe and research funding from Becton Dickinson. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Some of the key issues for use of the Cepheid assay revolve around whether patients will wait the 90 min that is required by the assay time. This issue may be a barrier to wide adoption of the assay as a ‘near-patient’ or point-of-care (POC) test in doctors’ offices and clinics. Potential ways to overcome such a barrier is to adjust clinic flow policies to begin the test procedure when the patient arrives to the clinic, although even with altering clinic flow, patients may not want to wait 90 min.

• Another barrier to uptake of such an assay is cost. Pricing will need to be competitive with other nucleic acid amplified test assays, as well as other rapid tests.

• At this time, the Centers for Disease Control and Prevention does not recommend the use of POC tests for chlamydia and gonorrhea, but as better tests evolve, this may change in future recommendations [8]. The literature has demonstrated generally poor performance of the use of POC tests for chlamydia in the clinic and field, thus far [9,10].