Background In many countries, patients with genital discharge syndrome (GDS) are treated syndromically with antibiotics that cover both Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT). The syndromic approach leads to both over-treatment (as most patients are not dually infected) and under-treatment (as asymptomatic infections are not detected). We studied the performance of the GeneXpert® nucleic acid amplification test (NAAT) as a testing platform for NG and CT in a study of the aetiology of GDS in Zimbabwe.
Materials and methods In an ongoing study, we enrolled 400 patients with GDS in 6 regionally diverse clinics in Zimbabwe serving high numbers of STI cases. Urine (men) and vaginal (women) specimens were taken for testing on 3 NAAT platforms: GeneXpert®, Probetec™ and multiplex polymerase chain reaction (M-PCR), conducted in different laboratories. We analysed overall concordance of results between platforms and assessed the performance of the GeneXpert® test when compared to a gold standard comprised of concordant results on both Probetec™ and M-PCR platforms.
Results To date, a total of 197 men and 200 women with GDS have been enrolled. Testing on all 3 platforms is complete for the 136 GDS patients enrolled in Harare. Concordance of positive or negative results for all 3 platforms was 133/136 (97.8%) for NG and 132/136 (97.0%) for CT. Sensitivity of the GeneXpert® platform compared to the Probetec™/M-PCR combined gold standard was 100% for both NG and CT; specificity was 98.8% for NG and 100% for CT.
Conclusions Aetiologic diagnosis has long been out of reach for many countries. However, the increasing presence of nucleic acid amplification test (NAAT) devices in many countries, such as GeneXpert®, for the diagnosis of tuberculosis and other infections, opens the possibility to use them for the diagnosis of other pathogens including NG and CT as an alternative or adjunct to syndromic management.
Disclosure of interest statement Nothing to declare.
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