PCR Detection and Sequencing of Trichomonas vaginalis in Women with Suspected Vaginitis in Southwestern Iran

Abstract

Introduction: The human being is considered a natural host for Trichomonas vaginalis (T. vaginalis), which causes trichomoniasis, the most frequent non-viral sexually transmitted infectious disease in the world. The current study aimed to evaluate the prevalence and sequencing of T. vaginalis in women with vaginitis. Methods: In the current research, 514 vaginal discharge samples were obtained from women with vaginitis. The specimens were evaluated by the direct wet mount examination, Dorset culture medium, and PCR technique. Primers were designed for the detection of TVK3/TVK7, TVA5/TVA6 genes specific for the identification of T. vaginalis. The PCR-positive samples were sequenced and compared with the sequences registered in the GenBank database. Results: Among the collected samples, 30 (5.83%), 45 (8.75%), 90 (17.50%), and 62 (12.06%) cases were positive for T. vaginalis when assayed by the direct wet mount examination, Dorset culture medium, and PCR technique (TVK3/TVK7, TVA5/TVA6 genes), respectively. There was no significant relationship between trichomoniasis and demographic characteristics of women, such as age, occupational status, mode of delivery, number of deliveries, educational level, and contraceptive methods (p˃0.05). The range of vaginal pH was between 5-7 in women with vaginitis, and there was a significant statistical correlation between the pH values and the infection rate (p<0.05). The PCR-positive samples had 100% sequence homology with the reference sequence in the GenBank database (accession number L23861.1). Conclusion: This study confirmed a relatively high prevalence of T. vaginalis in the southwestern region of Iran. According to our results, the PCR method, especially detecting TVK3/TVK7 genes, was more sensitive than the direct wet mount examination and Dorset culture medium methods.