Identification of Trichomonas Vaginalis Genotypes Using by Actin Gene and Molecular Based Methods in Southwest of Iran

Diagnostic accuracy of real-time polymerase chain reaction assay for the detection of Trichomonas vaginalis in clinical samples: A systematic review and meta-analysis

Background

Vaginal trichomoniasis is a highly prevalent parasitic infection associated with HIV acquisition and preterm birth. The 'gold standard' for its diagnosis requires 3-7 days to detect by culture. Rapid and accurate diagnosis, such as by nucleic acid amplification testing, is key to manage the disease, and control and prevent its transmission.

Aim

This review aimed to assess the overall accuracy of real-time polymerase chain reaction (RT-PCR)-based assays, for routine diagnosis of Trichomonas vaginalis in clinical vaginal samples from women with symptomatic/asymptomatic trichomoniasis, using Trichomonads culture as the gold standard.

Methods

MEDLINE, PubMed, EMBASE, and other sources were used to search for included studies published between 01 January 1995 and 31 July 2023. The search terms 'real-time polymerase chain reaction', 'real-time', 'polymerase chain reaction', 'Trichomonas vaginalis', 'trichomonas', 'vaginalis', 'humans', 'rt pcr', 'nucleic acid amplification test', 'NAAT', 'trichomonad culture', 'women' were included. Summary estimates were calculated for the overall accuracy of the assay compared to Trichomonads culture as the reference standard. Meta-analysis was conducted using a bivariate meta-regression model.

Results

Twenty-seven eligible studies met our inclusion criteria: sensitivity 99% (95% confidence interval [CI] 99-100), specificity 100% (95% CI 100-100), positive likelihood ratio 350.67 (167.42-734.49), negative likelihood ratio 0.02 (0.01-0.03), diagnostic odds ratio 23 064.05 (95% CI 8532.13-62 346.77), and area under receiver operating characteristics curve 0.99. There was significant heterogeneity in sensitivity and specificity (p < 0.001).

Conclusion

Our results suggested that RT-PCR assays could be useful for the diagnosis of vaginal trichomoniasis with high sensitivity and specificity.

What this study adds

This article provides a comprehensive review of the effectiveness of RT-PCR assays for the diagnosis of trichomoniasis with high sensitivity and specificity in comparison to other methods in clinical laboratory practice. The goal is to present awareness/evidence that this assay is more accurate and rapid than other techniques.

Construction a novel detection method for Trichomonas vaginalis based on recombinant enzyme polymerase amplification targeting the Actin gene

Trichomoniasis is a common and curable sexually transmitted disease worldwide. The rapid, convenient, and accurate diagnosis of trichomoniasis is an important link in the prevention and treatment of the disease. The current detection methods of Trichomonas vaginalis are mainly wet mount microscopy, culture, nested PCR, and loop-mediated isothermal amplification. However, these detection methods have some shortcomings. In this study, a recombinant enzyme polymerase amplification (RPA) assay had been conducted to detect T. vaginalis. The target gene and the corresponding primers were screened, and the reaction system and conditions were optimized in the assay of RPA. The sensitivity and specificity of this detection method were analyzed. The detection efficiency of wet mount microscopy, culture, nested PCR, and RPA was compared by testing 53 clinical samples from vaginal secretions. By screening, the actin gene of T. vaginalis could be used as a target gene for RPA detection of T. vaginalis, and the optimum reaction condition to amplify the actin gene by RPA was at 39°C for 30 min. The detection limit of T. vaginalis DNA using RPA was 1 pg, corresponding to a sensitivity of approximately five trophozoites. The RPA assay demonstrated high specificity for T. vaginalis, and there was no cross-reactivity with Giardia lamblia, Escherichia coli, Lactobacillus, Toxoplasma gondii, Staphylococcus aureus, and Candida albicans. Of the 53 clinical samples, the positive rates of T. vaginalis detected by wet mount microscopy, culture, nested PCR and RPA were 50.9 4% (27/53), 71.7% (38/53), 71.7% (38/53), and 69.81% (37/53), respectively. Compared with culture which was used as the gold standard for diagnosing trichomoniasis, testing clinical samples by wet mount microscopy showed 71.05% sensitivity, 100% specificity, and moderate diagnostic agreement with the culture (K = 0.581, Z = 4.661, p < 0.001). The nested PCR showed 100% sensitivity, 100% specificity, and excellent diagnostic agreement (K = 1, Z = 7.28, p < 0.001), while RPA displayed 97.37% sensitivity, 100% specificity, and excellent diagnostic agreement (K = 0.954, Z = 6.956, p < 0.001). At the present study, rapid amplification of actin gene by RPA could be used as a tool for detection of T. vaginalis. The detection method of RPA was more sensitive than wet mount microscopy and displayed excellent specificity. Moreover, RPA amplification of actin gene did not require a PCR instrument and the amplification time was shorter than that of ordinary PCR. Therefore, the RPA assay was proposed in this study as a point-of-care examination and a diagnostic method of T. vaginalis infection, which exhibited the potential value in the treatment and prevention of trichomoniasis.

Molecular characterization of Trichomonas infections in women of Ilam City, southwestern Iran

Trichomoniasis is a sexually transmitted infection (STI) caused by the flagellated protozoan Trichomonas vaginalis. Little information is available on the epidemiology and genetic diversity of T. vaginalis in Ilam City, southwestern Iran. A descriptive cross-sectional investigation was carried out between July 2017 and December 2018 on the suspected women patients referred to eight gynecology clinics of Ilam City for probable Trichomonas infection. They were undergone a set of clinical, parasitological, and molecular examinations. During clinical consultation, posterior vaginal fornix secretions and urine samples were gathered from the participants. For the reasons such as physical conditions and cultural and religious constraints, most of participating women, especially young girls due to their virginity, preferred to give urine samples instead of vaginal discharge. The presence of Trichomonas was diagnosed by microscopic examination and molecular detection using conventional PCR targeting ITS1-rDNA. A total of 1765 suspected individuals were examined clinically via vaginal secretions (495 specimens) and urine samples (1270 specimens). Of them, 21 (1.18%) cases, including 13 vaginal secretions and 8 urine samples, were positive for Trichomonas infection by microscopy. Slightly more than half of the patients (11/21, 52.4%) complained of vulvar itching, burning, and frequent urination. Cervical lesions, patchy erythema, and vaginal discharge were recorded in 28.6%, 23.8%, and 19% of the patients respectively. All patients with positive microscopic identification were confirmed by amplification of 450-bp fragment of ITS1-rDNA. Phylogenetic analysis revealed a high rate of genetic homogeneity in which all our isolates together with homologous sequences from China, Philippines, Austria, and USA were clustered within the same clade. A statistically significant relationship was recorded between the patients positive for trichomoniasis and the presence of chronic disease (e.g., diabetes, immune system deficiency).