Detection of common bacterial causes of urethritis in symptomatic men at the STD laboratory of MU-Sofia by microscopy, culture and NAAT

Abstract

INTRODUCTION: Urethritis is one of the major causes of morbidity in men. The primary pathogens are Chlamydia trachomatis and Neisseria gonorrhoeae, but also Mycoplasma genitalium . Ureaplasma urealyticum , Trichomonas vaginalis , anaerobes, Herpes simplex virus (HSV), and adenovirus. AIM: The aim of this study was to detect common bacterial causes of urethritis in symptomatic men by Gram stain, culture and nucleic acid amplification techniques (NAAT), and to compare them. MATERIALS AND METHODS: Seventy-eight male patients with clinical symptoms suggestive of urethritis were enrolled in the study. Three urethral samples were obtained from each one - for smear on a glass slide, culture, and NAAT. The glass slides were subjected to Gram stain. Culture on modified Thayer Martin media was used for detection of N. gonorrhoeae . Isolation of C. trachomatis was performed on McCoy cells, afterwards stained for immunofluorescence with anti-lipopolysaccharide monoclonal antibody. Cultivation and ennumeration of Ureaplasma spp. and M. hominis was done with Mycofast Revolution kit. DNA extractions and amplifications by using multiplex Real Time PCR tests were done for all the bacteria. RESULTS: In 30 persons, infections were detected by using different microbiological tests. N. gonorrhoeae was discovered by Gram stain in 5 samples; by cultivation - in 6; by PCR - in 8. C. trachomatis was found in 13 samples with cultivation; by PCR - in 14. Ureaplasma spp. was found in 7 samples with cultivation and in 9 with PCR. M. genitalium was detected only by PCR in 3 samples. M. hominis was negative in all tested swabs. Co-infections with two microorganisms were detected in 4 samples. All the samples with positive results showed increased number of leukocytes on Gram staining. DISCUSSION: Although many infections can be diagnosed on the basis of clinical criteria alone, accurate and timely diagnostic microbiology is essential for the clinical management of patients' infections. In our study the PCR was the most sensitive and rapid method for the diagnosis of urethritis in symptomatic men. Nevertheless we recommend that the test is combined with at least one more technique for greater accuracy in the interpretation of the results.