New Approach to Microscopy of Gram-Stained Urethral Smear: The Kissing Slide Method.

BACKGROUND: The effectiveness of microscopy of Gram-stained smear (GSS) for the detection of male urethral infection is debatable, especially in cases with low inflammation and no visible urethral discharge. This clinical study compared GSS samples collected with the conventional swab method and our new technique, the kissing slide method, together with polymerase chain reaction results to demonstrate the effectiveness of this new method in men with acute urethritis. METHODS: The study included 64 men who presented to the urology outpatient clinic with complaints of acute urethritis between October 2019 and January 2020. Two GSS samples were collected from each patient, first using the kissing slide method (applying the slide directly to the urethral mucosa), followed by the conventional method. The results were compared with polymerase chain reaction findings. RESULTS: The patients' mean age was 37.4 ± 7.8 years, and 68.7% had no visible urethral discharge on physical examination. At a GSS threshold of ≥5 polymorphonuclear leukocytes/high-power field, sensitivity values were 60% (95% confidence interval [CI], 42.32%-75.41%) for the kissing slide method and 23.33% (95% CI, 11.79%-40.93%) for the conventional method. At a threshold of ≥2 polymorphonuclear leukocytes/high-power field, sensitivity values with the kissing slide and conventional methods were 80% (95% CI, 62.69%-90.5%) and 50% (95% CI, 33.15%-66.85%) in all patients, and 66.67% (95% CI, 41.71%-84.82%) and 20% (95% CI, 7.047%-45.19%) in cases without visible urethral discharge, respectively. CONCLUSION: The new kissing slide method is a noninvasive alternative method that may have better sensitivity than the conventional GSS sampling method in the diagnosis of male acute urethritis. Randomized studies are needed to verify these findings.

Microscopy of Gram-stained urethral smear in the diagnosis of urethritis: Which threshold value should be selected?

The aim of this study was to investigate the sensitivity of GSS in the diagnosis of urethritis in patients who present to the outpatient clinic with symptoms of urethritis. Sixty-three male patients who presented to our outpatient clinic with symptoms of urethritis between January and March 2018 were evaluated. Urethral smear samples obtained from patients were evaluated both by GSS examination and by Real-time Multiplex Polymerase Chain Reaction (rt-MPCR) assay. The sensitivity and specificity of GSS in detecting gonococcal urethritis (GU) and nongonococcal urethritis (NGU) were calculated for threshold values of ≥5 and ≥2 PMNL/HPF. The mean age was 33.2 ± 7.1 years. According to the rt-MPCR results, 14 patients had GU and 27 patients had NGU. A threshold value of ≥5 PMNL/HPF in the GSS demonstrated 92.9% sensitivity in the diagnosis of GU and 55.6% sensitivity in the diagnosis of NGU. A threshold value of ≥2 PMNL/HPF reached 100% sensitivity for GU and 92.6% sensitivity for NGU. A cut-off value of ≥5 PMNL/HPF in the GSS has low sensitivity in the diagnosis of NGU. On the other hand, a threshold value of ≥2 PMNL/HPF seems to have higher sensitivity in the diagnosis of both GU and NGU.