TaqMan-based detection of Trichomonas vaginalis DNA from female genital specimens

Trichomonas Vaginalis Infection in Men with High-Risk Sexual Behaviors

Background:

Trichomonas vaginalis is a protozoan pathogen of the human genitourinary tract, which is the cause of trichomoniasis. The disease is one of the most important non-viral sexually transmitted infections in the world. Many studies have been performed on the molecular identification of Trichomonas in men in different parts of the world, but in Iran, such a study has been very limited. We aimed to detect T. vaginalis in urine of men with unusual sexual behavior by wet mount microscopic observation, culturing in TYM-33 and molecular method in Tehran, Iran.

Methods:

Totally, 47 urine samples were collected from men with high-risk sexual behaviors referred to Health Care Centers in South of Tehran, Iran during 2017–2018. After urine centrifugation and wet mount sediment preparation, the samples were cultured in TYM-33 medium and examined microscopically. Then DNA was extracted from urine sediment samples and finally the 18srRNA gene was amplified by PCR.

Results:

Thirty-one (65.95%) urine samples were positive for T. vaginalis by PCR. Of these, only 6 (12.76%) were detected positive by wet mount method and 25 (53.19%) by culture and successive passages.

Conclusion:

The high prevalence of trichomoniasis among men with high-risk sexual behavior in Tehran indicates a potent health risk condition for families. Of course, this percentage is not the real infection rate in ordinary men in Tehran. This situation could be controlled by promoting concurrent diagnosis and treatment of T. vaginalis infection in men and women, as well as strengthening religious beliefs and health education in the individuals.

United Kingdom National Guideline on the Management of Trichomonas vaginalis 2014

The main objective is to assist practitioners in managing men and women diagnosed withTrichomonas vaginalis(TV) infection. This guideline offers recommendations on the diagnostic tests, treatment regimens and health promotion principles needed for the effective management of TV, covering the management of the initial presentation, as well as how to prevent transmission and future infection.

Evaluation of polymerase chain reaction assays for the diagnosis of Trichomonas vaginalis infection in Russia

BACKGROUND

In Russia, the microscopy- and culture-based diagnostics of trichomoniasis is mainly suboptimal. Recent years, domestically produced diagnostic PCR assays have been implemented; however, any evaluation of these PCRs has never been internationally reported.

OBJECTIVE

To assess the performance characteristics of PCR assays developed and currently used in Russia to detect Trichomonas vaginalis.

MATERIALS AND METHODS

Five PCR assays were assessed on 448 samples (317 vaginal and 131 male urethral) collected from symptomatic attendees of youth centres (n = 415) and patients of a dermatovenereological dispensary that were previously diagnosed with trichomoniasis (n = 33). As reference assay, a sensitive and specific real-time multiplex PCR was used.

RESULTS

T. vaginalis DNA was detected in five (all females) of the 415 patients of youth centres (1.2%). All 33 patients previously diagnosed at the venereological dispensary proved to be true positive. For 445 (99.3%) of these 448 samples identical results were obtained by all PCRs, 35 positive and 410 negative. The three discordant samples were positive in all PCRs except one conventional PCR assay. The sensitivities of the PCRs were 94.3-100% and 66.7-100% for vaginal and urethral swabs, respectively. All evaluated assays were 100% specific. The detection limits of the different PCRs ranged from 0.1 to 5 genome equivalents per reaction.

CONCLUSION

The PCR assays currently used in Russia for the detection of T. vaginalis have in general high sensitivities and excellent specificities for both vaginal samples and urethral samples from males.

Molecular diagnosis of infections and resistance in veterinary and human parasites

Since 1977, >2000 research papers described attempts to detect, identify and/or quantify parasites, or disease organisms carried by ecto-parasites, using DNA-based tests and 148 reviews of the topic were published. Despite this, only a few DNA-based tests for parasitic diseases are routinely available, and most of these are optional tests used occasionally in disease diagnosis. Malaria, trypanosomiasis, toxoplasmosis, leishmaniasis and cryptosporidiosis diagnosis may be assisted by DNA-based testing in some countries, but there are very few cases where the detection of veterinary parasites is assisted by DNA-based tests. The diagnoses of some bacterial (e.g. lyme disease) and viral diseases (e.g. tick borne encephalitis) which are transmitted by ecto-parasites more commonly use DNA-based tests, and research developing tests for these species makes up almost 20% of the literature. Other important uses of DNA-based tests are for epidemiological and risk assessment, quality control for food and water, forensic diagnosis and in parasite biology research. Some DNA-based tests for water-borne parasites, including Cryptosporidium and Giardia, are used in routine checks of water treatment, but forensic and food-testing applications have not been adopted in routine practice. Biological research, including epidemiological research, makes the widest use of DNA-based diagnostics, delivering enhanced understanding of parasites and guidelines for managing parasitic diseases. Despite the limited uptake of DNA-based tests to date, there is little doubt that they offer great potential to not only detect, identify and quantify parasites, but also to provide further information important for the implementation of parasite control strategies. For example, variant sequences within species of parasites and other organisms can be differentiated by tests in a manner similar to genetic testing in medicine or livestock breeding. If an association between DNA sequence and phenotype has been demonstrated, then qualities such as drug resistance, strain divergence, virulence, and origin of isolates could be inferred by DNA-based tests. No such tests are in clinical or commercial use in parasitology and few tests are available for other organisms. Why have DNA-based tests not had a bigger impact in veterinary and human medicine? To explore this question, technological, biological, economic and sociological factors must be considered. Additionally, a realistic expectation of research progress is needed. DNA-based tests could enhance parasite management in many ways, but patience, persistence and dedication will be needed to achieve this goal.

Trichomoniasis and other sexually transmitted infections: results from the 2001-2004 National Health and Nutrition Examination Surveys

BACKGROUND

To estimate the association between Trichomonas vaginalis infection (TV) and 6 sexually transmitted infections: chlamydia, gonorrhea, herpes simplex virus (Types 1 and 2), syphilis, and human immunodeficiency virus (HIV) in a nationally representative sample.

METHODS

We used data from the National Health and Nutrition Examination Survey combining the 2001-2002 and 2003-2004 waves to estimate the association between TV and sexually transmitted infections (STIs) among women in the civilian, noninstitutionalized US population. The final sample included data from 3648 women, which when weighted, represents the experience of 65,563,298 US women between the ages of 14 and 49. Crude and adjusted relative risks were estimated using logistic regression for rare STIs (<10%; chlamydia, syphilis, and HIV) and Poisson regression for common STIs (herpes simplex virus [HSV] Types 1 and 2). Statistical analyses were conducted using Stata (version 9.2).

RESULTS

The prevalence of trichomoniasis was 3.2% with over 80% of cases asymptomatic in the past month. All STIs examined (chlamydia, gonorrhea, HSV-1, HSV-2, syphilis, and HIV) were more common among women with a positive test for trichomoniasis. HSV-1 (RR = 1.20, 95% CI: 1.09, 1.34) and HSV-2 (RR = 1.51, 95% CI: 2.32, 3.23) were significantly associated with trichomoniasis after adjusting for race/ethnicity, age, and recent sexual partners. In crude analyses, a positive treponemal test was 6 times (95% CI: 2.07, 18.8) more common and HIV was 13 times (95% CI: 2.88, 59.1) more common among women with trichomoniasis, but these estimates were greatly attenuated after adjustment for potential confounders.

CONCLUSION

Trichomoniasis is significantly associated with concurrent STI.

Prevalence of sexually transmitted infections among female adolescents aged 14 to 19 in the United States

OBJECTIVE

Most young women initiate sexual activity during adolescence; risk for sexually transmitted infections (STIs) accompanies this initiation. In this study we estimated the prevalence of the most common STIs among a representative sample of female adolescents in the United States.

METHODS

Data were analyzed from 838 females who were aged 14 to 19 and participating in the nationally representative National Health and Nutrition Examination Survey 2003-2004. After interview and examination, survey participants provided biological specimens for laboratory testing. The main outcome was weighted prevalence of at least 1 of 5 STIs: Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, herpes simplex virus type 2, and human papillomavirus (HPV) (any of 23 high-risk types or type 6 or 11).

RESULTS

Prevalence of any of the 5 STIs was 24.1% among all and 37.7% among sexually experienced female adolescents. HPV (23 high-risk types or type 6 or 11) was the most common STI among all female adolescents (prevalence: 18.3%), followed by C trachomatis infection (prevalence: 3.9%). Prevalence of any of the STIs was 25.6% among those whose age was the same or 1 year greater than their age at sexual initiation and 19.7% among those who reported only 1 lifetime sex partner.

CONCLUSIONS

The prevalence of STIs among female adolescents is substantial, and STIs begin to be acquired soon after sexual initiation and with few sex partners. These findings support early and comprehensive sex education, routine HPV vaccination at the age of 11 to 12 years, and C trachomatis screening of sexually active female adolescents.

Trichomoniasis in teens: an update

PURPOSE OF REVIEW

Trichomoniasis, caused by the protozoa Trichomonas vaginalis, is one of the oldest sexually transmitted infections. Since the advent of more accurate diagnostic tests, the epidemiology and consequences of infection with T. vaginalis can be described more precisely. This review will highlight new diagnostic methods, the epidemiology of trichomoniasis, and discuss the merits of improved screening for this pathogen in adolescent women.

RECENT FINDINGS

Interest in trichomoniasis has renewed due to evidence that trichomoniasis is more common than gonorrhea in adolescent women, is often asymptomatic, may persist for several months, and may be confused with bacterial vaginosis. In addition, trichomoniasis is linked to pelvic inflammatory disease and can increase one's susceptibility to viruses such as herpes, human papillomavirus, andHIV.

SUMMARY

Clinicians who use better diagnostic methods and offer more widespread testing will identify more infections and reduce the epidemic of this easily treated infection. Early diagnosis provides the opportunity to reduce transmission and potentially prevent future complications.

Comparison of APTIMA Trichomonas vaginalis transcription-mediated amplification to wet mount microscopy, culture, and polymerase chain reaction for diagnosis of trichomoniasis in men and women

OBJECTIVE

We evaluated the performance characteristics of APTIMA Trichomonas vaginalis (ATV) transcription-mediated amplification (TMA) for diagnosis of T vaginalis (TV) infection from female vaginal swab, endocervical swab, and urine specimens and from male urethral swab and urine specimens. Performance of ATV TMA was compared with wet mount microscopy, culture, and polymerase chain reaction (PCR).

STUDY DESIGN

In all, 296 female and 298 male subjects who attended the Jefferson County Health Department sexually transmitted diseases clinic were enrolled in the study and provided specimens for each test. Results were analyzed using 3 interpretative algorithms.

RESULTS

For women, vaginal swab ATV TMA was significantly more sensitive than wet mount or culture. In male subjects, urethral swab ATV TMA was significantly more sensitive than culture or PCR.

CONCLUSION

ATV TMA provides a sensitive, commercially available nucleic acid amplification test for improved diagnosis of TV in male and female patients.

Stability of Trichomonas vaginalis DNA in urine specimens

Trichomonas vaginalis is an important pathogen in both men and women. Culture is considered the diagnostic gold standard, although studies have shown that PCR is more sensitive than either culture or wet mount for the diagnosis of T. vaginalis infections. We sought to identify a simple method for stabilizing T. vaginalis DNA in urine samples that could be easily applied to molecular testing. The stability of T. vaginalis DNA in 40 urine samples was assessed by storage for various times at either 4 degrees C or room temperature with or without the Becton Dickinson urine preservative transport (UPT) kit. Overall, there was better stability of T. vaginalis DNA when specimens were stored at 4 degrees C than when they were stored at 20 to 22 degrees C and when the UPT system was used. T. vaginalis DNA was stable in specimens stored without using the UPT at 4 degrees C for about 3 days and at room temperature for only 1 day. For specimens placed in the UPT within 24 h (times of 1, 6, and 24 h) of collection, the DNA was stable for up to 30 days when stored at 4 degrees C. For specimens stored at room temperature, the urine should be added to the UPT ideally within 1 hour of collection, and in this case the DNA remained stable for up to 30 days. When storing specimens at room temperature, a delay of 24 h prior to adding to UPT led to an unacceptably high loss of assay sensitivity.

Real-time PCRs for detection of Trichomonas vaginalis beta-tubulin and 18S rRNA genes in female genital specimens

Trichomonas vaginalis is the cause of one of the most common types of vaginitis, trichomoniasis. The incidence of trichomoniasis in developed countries has decreased substantially during the past decade, but high prevalence of this disease can still be found in rural and remote areas of Australia. Clinical manifestations of symptomatic women are generally non-specific, but include vaginal discharge, vaginitis and irritation. T. vaginalis infection has also been linked to the increased risk of human immunodeficiency virus transmission. Current diagnosis of T. vaginalis relies on the visualization of motile organisms in a wet-mount preparation. Culture is used mainly in reference laboratories. The latter two methods require viable organisms and would not be suitable for use where transportation of specimens can be delayed. Two real-time fluorescence resonance energy transfer (FRET) hybridization probe PCR assays were used in this study to test for T. vaginalis DNA, targeting the beta-tubulin and 18S rRNA genes. We tested 500 randomly selected female patients, in an STD setting, for T. vaginalis DNA. The FRET PCRs targeting the beta-tubulin gene and the 18S rRNA gene detected 96 % (85/89) and 100 % (89/89) , respectively, of the positive specimens (first-void urine sample or genital swabs). Wet-mount microscopy was performed on 76 of these PCR-positive specimens and showed a sensitivity of 38 % (29/76). The prevalence, by PCR, of trichomoniasis was 18 % in this study. The two real-time PCRs developed in this study, targeting different genetic regions of the organism, provide a rapid, sensitive and specific diagnosis of T. vaginalis infection.

Improved detection of Tritrichomonas foetus in bovine diagnostic specimens using a novel probe-based real time PCR assay

A Tritrichomonas foetus-specific 5' Taq nuclease assay using a 3' minor groove binder-DNA probe (TaqMan MGB) targeting conserved regions of the internal transcribed spacer-1 (ITS-1) was developed and compared to established diagnostic procedures. Specificity of the assay was evaluated using bovine venereal microflora and a range of related trichomonad species. Assay sensitivity was evaluated with log(10) dilutions of known numbers of cells, and compared to that for microscopy following culture (InPouch TF test kit) and the conventional TFR3-TFR4 PCR assay. The 5' Taq nuclease assay detected a single cell per assay from smegma or mucus which was 2500-fold or 250-fold more sensitive than microscopy following selective culture from smegma or mucus respectively, and 500-fold more sensitive than culture followed by conventional PCR assay. The sensitivity of the conventional PCR assay was comparable to the 5' Taq nuclease assay when testing purified DNA extracted from clinical specimens, whereas the 5' Taq nuclease assay sensitivity improved using crude cell lysates, which were not suitable as template for the conventional PCR assay. Urine was evaluated as a diagnostic specimen providing improved and equivalent levels of T. foetus detection in spiked urine by both microscopy following culture and direct 5' Taq nuclease detection, respectively, compared with smegma and mucus, however inconclusive results were obtained with urine samples from the field study. Diagnostic specimens (n=159) were collected from herds with culture positive animals and of the 14 animals positive by 5' Taq nuclease assay, 3 were confirmed by selective culture/microscopy detection (Fisher's exact test P<0.001). The 5' Taq nuclease assay described here demonstrated superior sensitivity to traditional culture/microscopy and offers advantages over the application of conventional PCR for the detection of T. foetus in clinical samples.

Trichomonas vaginalis detection using real-time TaqMan PCR

1978 women and 93 men, all suspected of having a Trichomonas vaginalis infection, were tested for the presence of T. vaginalis by real-time PCR using the T. vaginalis-specific 2-kb repeated sequence, and by direct microscopy and culture. 40 samples were positive by T. vaginalis real-time PCR and 27 were positive by wet mount microscopy, either direct or after culture. All samples positive by direct microscopy of culture were also positive by real-time PCR. Of the 13 samples which were real-time PCR positive but negative by direct microscopy and culture 11 were confirmed by another T. vaginalis real-time PCR based on the beta tubulin gene. Only 2 samples (0.1%) showed inhibition in the PCR. The prevalence of T. vaginalis infection in the female patients was 1.8%. The sensitivity, specificity, positive and negative predictive values of the real-time PCR were 100%, 99.9%, 95% and 100%, respectively. The same test characteristics for the combined conventional T. vaginalis detection methods (microscopy+culture) were 71%, 100%, 100% and 99%, respectively. Therefore, real-time PCR is the method of choice for the diagnosis of T. vaginalis infection.

Comparison between the Gen-Probe transcription-mediated amplification Trichomonas vaginalis research assay and real-time PCR for Trichomonas vaginalis detection using a Roche LightCycler instrument with female self-obtained vaginal swab samples and male urine samples

This study compared two assays for Trichomonas vaginalis detection, Gen-Probe's transcription-mediated amplification (TMA) assay for Trichomonas vaginalis and BTUB FRET PCR, using self-obtained clinical samples from 611 patients. Infection status was defined as two positive results by two different tests. The initial TMA assay sensitivity was 96.7%; specificity was 97.5%. The TMA assay was comparable to BTUB FRET PCR.

Comparison of culture and a novel 5' Taq nuclease assay for direct detection of Campylobacter fetus subsp. venerealis in clinical specimens from cattle

A Campylobacter fetus subsp. venerealis-specific 5' Taq nuclease PCR assay using a 3' minor groove binder-DNA probe (TaqMan MGB) was developed based on a subspecies-specific fragment of unknown identity (S. Hum, K. Quinn, J. Brunner, and S. L. On, Aust. Vet. J. 75:827-831, 1997). The assay specifically detected four C. fetus subsp. venerealis strains with no observed cross-reaction with C. fetus subsp. fetus-related Campylobacter species or other bovine venereal microflora. The 5' Taq nuclease assay detected approximately one single cell compared to 100 and 10 cells in the conventional PCR assay and 2,500 and 25,000 cells from selective culture from inoculated smegma and mucus, respectively. The respective detection limits following the enrichments from smegma and mucus were 5,000 and 50 cells/inoculum for the conventional PCR compared to 500 and 50 cells/inoculum for the 5' Taq nuclease assay. Field sampling confirmed the sensitivity and the specificity of the 5' Taq nuclease assay by detecting an additional 40 bulls that were not detected by culture. Urine-inoculated samples demonstrated comparable detection of C. fetus subsp. venerealis by both culture and the 5' Taq nuclease assay; however, urine was found to be less effective than smegma for bull sampling. Three infected bulls were tested repetitively to compare sampling tools, and the bull rasper proved to be the most suitable, as evidenced by the improved ease of specimen collection and the consistent detection of higher levels of C. fetus subsp. venerealis. The 5' Taq nuclease assay demonstrates a statistically significant association with culture (chi2 = 29.8; P < 0.001) and significant improvements for the detection of C. fetus subsp. venerealis-infected animals from crude clinical extracts following prolonged transport.

Real-time PCR improves detection of Trichomonas vaginalis infection compared with culture using self-collected vaginal swabs

OBJECTIVE: To compare a real-time polymerase chain reaction (PCR) assay with broth culture for the detection of Trichomonas vaginalis using self-collected vaginal swabs. METHODS: Self-collected vaginal swabs were obtained from adolescent and young adult African-American women participating in HIV-1 prevention programs. T. vaginalis culture was performed using the InPouch TV System. Samples for the real-time PCR assay were collected using the BDProbeTec ET Culturette Direct Dry Swab system and tested in a laboratory-developed assay which targeted a repeated sequence of the genome. Discrepant samples that were culture negative and positive in the real-time PCR assay were tested in a confirmatory PCR which targeted a different region of the T. vaginalis genome, the18S ribosomal DNA gene. RESULTS: Of the 524 specimens tested by both culture and real-time PCR, 36 were culture positive and 54 were positive in the real-time PCR assay; 16 of the 18 discrepant specimens were also positive in the confirmatory PCR assay. Using a modified gold standard of positive by culture or positive in both PCR assays, the sensitivity of the real-time PCR assay was 100% and the specificity was 99.6%, whereas culture had a sensitivity of 69.2% and a specificity of 100%. CONCLUSIONS: The real-time PCR assay was sensitive and specific for the detection of T. vaginalis DNA from self-collected vaginal swab specimens. The ability to use the BDProbeTec dry swab system for the real-time PCR testing allowed for the detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and T. vaginalis from a single specimen.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

Comparison of the Specificity and Sensitivity of PCR, Nested PCR, and Real-Time PCR for the Diagnosis of Histomoniasis

Blackhead, also known as enterohepatitis, is caused by a protozoan parasite called Histomonas meleagridis. Clinical symptoms are nonspecific. Until now, diagnosis has been mainly based on postmortem lesions and microscopical and histopathological examination. In many cases, especially in layer flocks, these conventional methods are not sufficient, as the lesions are sometimes not clear. The technique for isolation of histomonads in vitro offers many advantages, but the confirmation of histomonads growing in culture may require a time-consuming procedure of rectal inoculation of culture material into chickens or turkeys. The aim of our investigation was to establish a conventional polymerase chain reaction (PCR), a nested PCR, and a real-time PCR, and to examine their specificity as well as sensitivity in the diagnosis of histomoniasis. The obtained results have shown that the conventional PCR is more sensitive than the real-time PCR. Furthermore, the sensitivity of the PCR can be increased by adding the nested PCR. However, the real-time PCR is more specific.

The diagnosis ofTrichomonas vaginalis in liquid-based Pap tests: Correlation with PCR

The conventional Papanicolaou smear (CPS) is not considered accurate for the diagnosis of Trichomonas vaginalis (T. vaginalis), and women noted to carry the organism on CPS are recommended to undergo confirmatory testing. Liquid-based preparations have been shown to facilitate the diagnosis of squamous lesions and may also facilitate the diagnosis of T. vaginalis. We used polymerase chain reaction (PCR) to investigate the accuracy of the diagnosis of T. vaginalis by the liquid-based Pap test (LBP). LBP with the diagnosis of T. vaginalis from a 12-mo period were identified. Residual samples from these cases were subjected to PCR for T. vaginalis as were the residual samples of a control group of 195 LBP (including 103 inflammatory LBP and 69 cases of atypical squamous cells) in which T. vaginalis was not diagnosed cytologically. PCR confirmed the presence of T. vaginalis in 50 of 51 (98%) LBP and identified 2 additional cases. Morphologic identification of T. vaginalis on LBP is highly accurate and should not require confirmatory testing.

Use of the Roche LightCycler instrument in a real-time PCR for Trichomonas vaginalis in urine samples from females and males

Trichomonas vaginalis is the agent of a highly prevalent sexually transmitted infection (STI) that can result in vaginitis, urethritis, and preterm birth. Traditional methods of diagnosis, including wet preparation, can be unreliable. In this study, we describe the adaptation of an existing PCR method for specific detection of T. vaginalis DNA into a rapid real-time PCR assay based on fluorescence resonance energy transfer (FRET) probe chemistry. The FRET-based assay described demonstrated high sensitivity with a detection limit of 1.06 organisms, as well as a high specificity. A total of 253 urine samples collected prospectively from both men and women were tested for T. vaginalis DNA with both the FRET-based assay and a previously validated PCR assay. When the validated PCR assay was used as the "gold standard" and after discrepancies had been resolved, our FRET-based assay demonstrated an analytical sensitivity and specificity of 90.1 and 100%, respectively. Overall results suggest that FRET-based assays can provide rapid, accurate, and high-throughput detection of T. vaginalis and may prove useful in clinical settings and for large-scale screening programs.