Introduction Gonorrhoea is a common sexually transmitted disease caused by Neisseria gonorrhoeae (Ng) infection. Light microscopy of urogenital smears is used as a simple tool to diagnose urogenital gonorrhoea in many resource-limited settings. We aimed to evaluate the accuracy of light microscopy to diagnose urogenital gonorrhoea as compared to a PCR based test.
Methods In 2014, we examined 632 male urethral and 360 endocervical smears in clinic-based and outreach settings in Jakarta, Yogyakarta and Denpasar, Indonesia. Using the detection of Ng DNA by a validated PCR as reference test, we evaluated the accuracy of two light microscopic criteria to diagnose urogenital gonorrhoea in genital smears: 1) the presence of intracellular Gram negative diplococci (IGND) and 2)≥5 polymorphonuclear leukocytes (PMNL)/oil-immersion field (oif) in urethral, or >20 PMNL/oif in endocervical smears.
Results In male urethral smears, IGND testing had a sensitivity, specificity, and kappa of respectively 59.0%, 89.4%, and 0.49. For PMNL count these were respectively 59.0%, 83.7%, and 0.40. The accuracy of IGND in the clinic-based settings (respectively 72.0%, 95.2%, and 0.68) was better than in the outreach settings (respectively 51.2%, 83.4%, and 0.35). In endocervical smears, light microscopy performed poorly regardless of the setting or symptomatology, with kappas ranging from 0.09 to 0.24.
Conclusion Light microscopy using IGND and PMNL criteria can be an option with moderate accuracy to diagnose urethral gonorrhoea among males in a clinic-based setting. The poor accuracy in detecting endocervical infections indicates an urgent need to implement advanced methods, such as PCR. Further investigations are needed to identify the poor diagnostic outcome in outreach services.
Support: This study was fully funded by Excellence Scholarship Program (Beasiswa Unggulan), Ministry of Research, Technology and Higher Education, Republic of Indonesia
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