Improved diagnosis of Trichomonas vaginalis infection by PCR using vaginal swabs and urine specimens compared to diagnosis by wet mount microscopy, culture, and fluorescent staining

British Association for Sexual Health and HIV (BASHH) United Kingdom national guideline on the management of Trichomonas vaginalis 2021

The main objective of this guideline is to assist practitioners in managing individuals diagnosed with Trichomonas vaginalis (TV). It offers recommendations on the diagnostic tests, treatment regimens and health promotion principles needed for the effective management of TV. It covers the management of the initial presentation, as well as how to prevent transmission and future re-infection. It is aimed primarily at people aged 16 years or older presenting to health care professionals, working in departments offering specialist care in sexually transmitted infection (STI) management within the United Kingdom. However, the principles of the recommendations are applicable across all levels of STI care providers (N.B. non-specialist services may need to develop, where appropriate, local care pathways).

Comparison of diagnostic methods and analysis of socio-demographic factors associated with Trichomonas vaginalis infection in Sri Lanka

BACKGROUND

Trichomonas vaginalis infection is underreported due to nonspecific clinical presentation and the nonavailability of sensitive laboratory diagnostic tests at the clinical setup. Hence, this study was designed to compare the sensitivity and specificity of microscopy and culture methods with polymerase chain reaction (PCR). The socio-demographic factors associated with the infection were explored.

METHODS

The study was carried out at the National Sexually Transmitted Diseases and Acquired Immuno Deficiency Syndrome Control Programme in Colombo and Sexually Transmitted Diseases and Acquired Immuno Deficiency Syndrome Control Programme in Kandy. Samples were collected from a total of 385 patients including, 272 females (70.7%) and 113 males (29.3%), and tested using microscopy (wet mount and Giemsa staining), culture, and PCR. Genus-specific primer set (TFR1/TFR2) that amplifies 5.8S rRNA and species-specific primer sets (TV16Sf-2/TV16Sr-2 and TVK3/7) that amplifies 18S rRNA and repetitive DNA, respectively, were used. Patient's socio-demographic and sexual behaviour data were obtained using a standard interviewer-administered questionnaire. Data were analyzed with R statistical software Version 3.6.3.

RESULTS

The overall prevalence of trichomoniasis was 4.4% (17/385). Of these, six (1.6%) were positive for microscopic examination, 7 (1.8%) were positive for culture, and 13 (3.4%) for TVK3/7, 15 (3.9%) for TV16Sf/r, and TFR1/2 17 (4.4%) were positive for PCR. Sensitivities of PCR using TFR1/2, TV16Sf/r, and TVK3/7 primer sets were 100%, 88.20%, and 76.50%, respectively, against the expanded gold standard. Trichomoniasis was associated with age above 36 (p = 0.033), not using condoms in last three months (p = 0.016), multiple sex partners (p = 0.001), reason for attendance (p = 0.027), symptomatic nature (p = 0.015), and the presence of other sexually transmitted diseases (p = 0.001).

CONCLUSIONS

The study highlighted that age over 36 years, multiple sex partners, not using condoms, reason for attendance, symptomatic nature, and having other sexually transmitted diseases can increase the risk of acquiring trichomoniasis. Furthermore, this study confirmed PCR as highly sensitive and specific diagnostic test for the diagnosis of trichomoniasis in comparison to microscopy and culture methods.

Prevalence and factors associated with trichomonas vaginalis infection among female sex workers in Togo, 2017

BACKGROUND

The aim of this study was to estimate the prevalence and factors associated with Trichomonas vaginalis (T. vaginalis) among female sex workers (FSW) in Togo in 2017. A cross-sectional bio-behavioral study was conducted from August to October 2017 using a respondent-driven sampling method in four cities in Togo.

METHOD

A standardized questionnaire was used to record socio-demographic data and sexual behavior patterns. T. vaginalis detection by molecular biology tests was performed using Allplex STI Essential Assay which detect also 6 others micro-organisms. A blood sample was drawn and serological test using SD Bioline Duo VIH/Syphilis rapid test was performed for Human immunodeficiency virus (HIV) and syphilis testing.

RESULTS

A total of 310 FSW with median age 25 years, interquartile range (IQR) [21-32 years] were included. The prevalence of T. vaginalis was 6.5% (95%CI = [4.1-9.9]) and, overall, prevalence of other STI ranged from 4.2% (95%CI = [2.3-7.2]) for N. gonorrhoeae to 10.6% (95% CI = [7.5-14.7]) for HIV. Binary logistic regression was conducted to assess factors associated with T. vaginalis infection. Living in Lomé (aOR = 3.19; 95%CI = [1.11-11.49]), having had sexual intercourse before the age of 18 (aOR = 5.72; 95%CI = [1.13-10.89]), and being infected with C. trachomatis (aOR = 3.74; 95%CI = [2.95-12.25]) were factors associated with T. vaginalis among FSW.

CONCLUSION

The prevalence of T. vaginalis infection using molecular test was low among FSW in Togo. Extensive studies are needed to confirm and to better understand the epidemiology of T. vaginalis among this population and in other populations in Togo.

The International Society for the Study of Vulvovaginal Disease Vaginal Wet Mount Microscopy Guidelines: How to Perform, Applications, and Interpretation

OBJECTIVES

The aims of the study were to assess the available literature concerning the indications, performance, technique, and classification of wet mount microscopy (WMM) and to establish evidence-based recommendations.

METHODS

Literature review from the main scientific databases was performed by the ad hoc "Vaginitis and Microbiome Committee" of the International Society for the Study of Vulvovaginal Disease. The document was approved by the executive council and membership of the International Society for the Study of Vulvovaginal Disease.

RESULTS

Available data are limited and usually of low level of evidence. Nevertheless, it shows that WMM is capable of reducing misdiagnosis, overtreatment, and undertreatment of vaginal conditions. It has an excellent performance for the diagnosis of bacterial vaginosis and variable performance for trichomoniasis and candidiasis. It is the gold standard for aerobic vaginitis/desquamative inflammatory vaginitis. Currently, there is no recommendation to use WMM in the screening of asymptomatic women.The use of phase contrast is recommended to improve performance and reproducibility. Sampling location, devices, and technique have an impact on the results.Available scoring and classification scores have significant limitations.

CONCLUSIONS

Wet mount microscopy is a point-of-care, inexpensive, and fast technique that, with practice, can be mastered by office clinicians. It should be considered a basic skill in the curricula of gynecology and obstetrics residencies. Recommendations are provided on sampling, reading, and scoring.

Trichomonas vaginalis infection and the diagnostic significance of detection tests among Ghanaian outpatients

Background

There is little data on Trichomonas vaginalis infection in Ghana. This study evaluated the prevalence of trichomoniasis using different diagnostic methods and determined the risk factors for infection in patients.

Methods

A structured questionnaire was administered. Vaginal swabs, urethral swabs and urine specimens were obtained from consenting patients; and the samples processed following standard protocols. The presence of T. vaginalis was determined using wet mount microscopy and polymerase chain reaction (PCR) as gold standard. We also assessed the diagnostic performance the JD’s Trichomonas V® rapid antigen test to inform clinical practice.

Results

The PCR assay detected T. vaginalis positivity in 64 of 150 patients (42.6, 95%CI:35.0, 50.6) including all positive samples of wet mount microscopy and JD’s Trichomonas V® test. Wet mount microscopy showed low sensitivity (31.6%), high specificity (100%), moderate positive predictive value (75.0%), moderate positive likelihood ratio (3.0), and weak agreement (Cohen’s kappa, 0.283) with PCR assay. The JD’s Trichomonas V® test displayed lower sensitivity (25.0%), specificity (83.3%), and weaker measure of agreement (Cohen’s kappa, 0.233) with PCR. In multivariate analysis, the strongest independent predictor for T. vaginalis was female gender [adjusted odds ratio (AOR), 24.89; 95% confidence interval (CI): 10.58, 51.21; P-value< 0.001]. Knowledge of STI showed a protective effect against infection with the parasite (AOR, 0.13; 95%CI: 0.07, 0.29; P-value< 0.017).

Conclusion

The sensitivity of wet mount microscopy was low for T. vaginalis screening in our region. The JD’s Trichomonas V® test should not be considered as an alternative test. We recommend mandatory PCR assay for confirmation of negative wet mount results.

2018 European (IUSTI/WHO) International Union against sexually transmitted infections (IUSTI) World Health Organisation (WHO) guideline on the management of vaginal discharge

Four common pathological conditions are associated with vaginal discharge: bacterial vaginosis, aerobic vaginitis, candidosis, and the sexually transmitted infection, trichomoniasis. Chlamydial or gonococcal cervical infection may result in vaginal discharge. Vaginal discharge may be caused by a range of other physiological and pathological conditions including atrophic vaginitis, desquamative inflammatory vaginitis, cervicitis, and mucoid ectopy. Psychosexual problems may present with recurrent episodes of vaginal discharge and vulval burning. These need to be considered if tests for specific infections are negative. Many of the symptoms and signs are non-specific and a number of women may have other conditions such as vulval dermatoses or allergic and irritant reactions.

Prevalence of Trichomonas vaginalis infection and protozoan load in South African women: a cross-sectional study

OBJECTIVES

Trichomonas vaginalis is thought to be the most common non-viral sexually transmitted infection worldwide. We investigated the prevalence, risk factors and protozoan load of T. vaginalis infection in South African women.

METHODS

A cross-sectional study of 604 women was conducted at 25 primary healthcare facilities in rural South Africa (Mopani district). T. vaginalis DNA was detected in vaginal and rectal swabs. In univariate and multivariate analyses, the T. vaginalis infection was investigated in relation to demographic characteristics, medical history and behavioural factors. The T. vaginalis load was determined as the logarithm of DNA copies per microlitre sample solution.

RESULTS

Collected vaginal and rectal swabs were tested for T. vaginalis DNA. Prevalence of vaginal T. vaginalis was 20% (95% CI 17.0% to 23.4%) and rectal 1.2% (95% CI 0.6% to 2.4%). Most women (66%) with a vaginal infection were asymptomatic. Factors associated with T. vaginalis infection were a relationship status of single (OR 2.4; 95% CI 1.5 to 4.0; p<0.001) and HIV positive infection (OR 1.6; 95% CI 1.0 to 2.6; p=0.041). Women with vaginal T. vaginalis infection were more likely to have concurrent Chlamydia trachomatis rectal infection than those without vaginal infection (12%vs3%; p<0.001; OR 4.1). A higher median T. vaginalis load was observed among women with observed vaginal discharge compared with those without vaginal discharge (p=0.025).

CONCLUSIONS

Vaginal trichomoniasis is highly prevalent in rural South Africa, especially among single women and those with HIV infection, and often presents without symptoms.

Unique Trichomonas vaginalis gene sequences identified in multinational regions of Northwest China

Trichomonas vaginalis (T. vaginalis) is a flagellated protozoan parasite that infects humans worldwide. This study determined the sequence of the 18S ribosomal RNA gene of T. vaginalis infecting both females and males in Xinjiang, China. Samples from 73 females and 28 males were collected and confirmed for infection with T. vaginalis, a total of 110 sequences were identified when the T. vaginalis 18S ribosomal RNA gene was sequenced. These sequences were used to prepare a phylogenetic network. The rooted network comprised three large clades and several independent branches. Most of the Xinjiang sequences were in one group. Preliminary results suggest that Xinjiang T. vaginalis isolates might be genetically unique, as indicated by the sequence of their 18S ribosomal RNA gene. Low migration rate of local people in this province may contribute to a genetic conservativeness of T. vaginalis. The unique genetic feature of our isolates may suggest a different clinical presentation of trichomoniasis, including metronidazole susceptibility, T. vaginalis virus or Mycoplasma co-infection characteristics. The transmission and evolution of Xinjiang T. vaginalis is of interest and should be studied further. More attention should be given to T. vaginalis infection in both females and males in Xinjiang.

Recombinant α-actinin subunit antigens of Trichomonas vaginalis as potential vaccine candidates in protecting against trichomoniasis

Background

Human trichomoniasis caused by Trichomonas vaginalis is one of the most common sexually transmitted diseases with more than 200 million cases worldwide. It has caused a series of health problems to patients. For prevention and control of infectious diseases, vaccines are usually considered as one of the most cost-efficient tools. However, until now, work on the development of T. vaginalis vaccines is still mainly focused on the screening of potential immunogens. Alpha-actinin characterized by high immunogenicity in T. vaginalis was suggested as a promising candidate. Therefore, the purpose of this study was to evaluate the protective potency of recombinant α-actinin against T. vaginalis infection in a mouse intraperitoneal model.

Methods

Two selected coding regions of α-actinin (ACT-F, 14–469 aa and ACT-T, 462–844 aa) amplified from cDNA were cloned into pET-32a (+) expression vector and transfected into BL21 cells. After induction with IPTG and purification with electroelution, the two recombinant fusion proteins were emulsified in Freund’s adjuvant (FA) and used to immunize BALB/C mice. Following intraperitoneal inoculation with T. vaginalis, the survival rate of mice was monitored for the assessment of protective potency. After immunization, the antibody level in mouse serum was assessed by ELISA, splenocyte proliferation response was detected with CCK8 and cytokines in the supernatant of splenocytes were quantified with a cytometric bead-based assay.

Results

We successfully obtained purified ACT-F (70.33 kDa) and ACT-T (61.7kDa). Both recombinant proteins could provide significant protection against T. vaginalis challenge, especially ACT-T (with 100% protection within one month). Meanwhile, high levels of specific total IgG and subtypes (IgG1 > IgG2a) were detected in sera from the immunized mice. Our results also revealed a statistically significant increase in splenocyte proliferation and related cytokine (IFN-γ, IL-6, IL-17A and IL-10) production after repeated stimulation with the corresponding antigens in vitro.

Conclusions

Immunization with both ACT-F and ACT-T could confer partial to complete protection and trigger strong Th1/Th2 mixed humoral and cellular immune responses in the mouse host. This suggested that recombinant α-actinin subunit antigens may be promising vaccine candidates against trichomoniasis.

Prevalence of Trichomonas vaginalis in Women Visiting 2 Obstetrics and Gynecology Clinics in Daegu, South Korea

This study explored epidemiological trends in trichomoniasis in Daegu, South Korea. Wet mount microscopy, PCR, and multiplex PCR were used to test for Trichomonas vaginalis in vaginal swab samples obtained from 621 women visiting 2 clinics in Daegu. Of the 621 women tested, microscopy detected T. vaginalis in 4 (0.6%) patients, PCR detected T. vaginalis in 19 (3.0%) patients, and multiplex PCR detected T. vaginalis in 12 (1.9%) patients. Testing via PCR demonstrated high sensitivity and high negative predictive value for T. vaginalis. Among the 19 women who tested positive for T. vaginalis according to PCR, 94.7% (18/19) reported vaginal signs and symptoms. Notably, more than 50% of T. vaginalis infections occurred in females younger than 30 years old, and 58% were unmarried. Multiplex PCR, which simultaneously detects pathogens from various sexually transmitted infections, revealed that 91.7% (11/12) of patients were infected with 2 or more pathogens. Mycoplasma hominis was the most prevalent co-infection pathogen with T. vaginalis, followed by Ureaplasma urealyticum and Chlamydia trachomatis. Our results indicate that PCR and multiplex PCR are the most sensitive tools for T. vaginalis diagnosis, rather than microscopy which has been routinely used to detect T. vaginalis infections in South Korea. Therefore, clinicians should take note of the high prevalence of T. vaginalis infections among adolescent and young women in order to prevent persistent infection and transmission of this disease.

Evaluation of Different Staining Techniques in the Diagnosis of Trichomonas vaginalis Infection in Females of Reproductive Age Group

BACKGROUND

Trichomonas vaginalis is a parasitic protozoan which causes most common non viral sexually transmitted disease trichomoniasis. Direct microscopic examination of vaginal fluid remains the most widely used diagnostic test. Although, wet mount examination is the most cost-effective diagnostic test, but it has low sensitivity resulting in under diagnosis of the disease. Therefore, to overcome this problem, various staining techniques like giemsa and acridine orange can be used along with wet mount examination for diagnosis of T. vaginalis infection.

OBJECTIVE

The present study was done to evaluate the efficacy of Giemsa and Acridine Orange staining in comparison with wet mount examination for the diagnosis of vaginal trichomoniasis.

MATERIALS AND METHODS

A total of 615 female patients of reproductive age group having vaginal discharge were included in the study and swabs containing vaginal fluids were taken to perform wet mount examination, giemsa staining and acridine orange staining.

RESULT

Trichomonas vaginalis infection was detected in 37 patients with maximum cases (6.0%) detected by acridine orange staining, followed by giemsa staining (4.9%), whereas, wet mount examination was able to detect only 4.1% cases. Wet mount examination gave a sensitivity of 67.6%, whereas, the sensitivity of giemsa staining and acridine orange staining was found to be 80% and 100% respectively.

CONCLUSION

Since the performance of both the staining techniques was found to be much better in comparison to wet mount examination, and they also detected several wet mount negative cases, they should be used as an adjunct to wet mount examination. This will also be beneficial to the overall health of the patient by early diagnosis and treatment of cases, thereby, reducing the development of associated morbidity.

A Diagnostic and Symptomatological Study on Trichomoniasis in Symptomatic Pregnant Women in Rafsanjan, South Central Iran in 2012-13

BACKGROUND

Trichomonas vaginalis, the causative agent of trichomoniasis, is responsible for more than half of all sexually transmitted infections (STIs). The present study aimed to determine the frequency of T. vaginalis infection and its clinical manifestations in symptomatic pregnant women in the area based on four different diagnostic methods.

METHODS

A total of 162 pregnant women with at least one sign or symptom of vaginosis, referred to two gynecologic and obstetrics clinics in Rafsanjan City, south central Iran, were randomly selected in 2012-13. Through speculum examination of patients by gynecologists, clinical diagnosis determined, vaginal discharge were collected by using two sterile cotton swabs from the posterior fornix and vagina pH was measured. Samples were examined by three diagnostic methods including wet mount, culture in TYI-S-33 medium and polymerase chain reaction (PCR).

RESULTS

T. vaginalis was detected in 19.5%, 27.2%, 56.2% and 51.6% of subjects according to diagnostic methods of clinical diagnosis, wet mount, culture and PCR, respectively. There was statistically significant relationship between T. vaginalis infection and patients' age, gestational age, marriage age, residence, educational level, parity. The symptomatological pattern in the 91 women infected with T. vaginalis was as follows: leukorrhea, 96.7%; urine frequency, 65.9%; odorous secretion, 63.3%; urogenital itching and irritation, 53.8%; vaginal inflammation, 47.3%; dyspareunia, 39.6%; and dysuria, 16.5%.

CONCLUSION

Our results indicated a high prevalence of T. vaginalis in symptomatic pregnant women, very low sensitivity and relative high specificity of clinical diagnosis and wet mount technique compared to culture and PCR, as well as thatpregnancy increases the susceptibility to the infection in a gestational age-dependent manner.

Swab sample transfer for point-of-care diagnostics: characterization of swab types and manual agitation methods

BACKGROUND

The global need for disease detection and control has increased effort to engineer point-of-care (POC) tests that are simple, robust, affordable, and non-instrumented. In many POC tests, sample collection involves swabbing the site (e.g., nose, skin), agitating the swab in a fluid to release the sample, and transferring the fluid to a device for analysis. Poor performance in sample transfer can reduce sensitivity and reproducibility.

METHODS

In this study, we compared bacterial release efficiency of seven swab types using manual-agitation methods typical of POC devices. Transfer efficiency was measured using quantitative PCR (qPCR) for Staphylococcus aureus under conditions representing a range of sampling scenarios: 1) spiking low-volume samples onto the swab, 2) submerging the swab in excess-volume samples, and 3) swabbing dried sample from a surface.

RESULTS

Excess-volume samples gave the expected recovery for most swabs (based on tip fluid capacity); a polyurethane swab showed enhanced recovery, suggesting an ability to accumulate organisms during sampling. Dry samples led to recovery of ∼20-30% for all swabs tested, suggesting that swab structure and volume is less important when organisms are applied to the outer swab surface. Low-volume samples led to the widest range of transfer efficiencies between swab types. Rayon swabs (63 µL capacity) performed well for excess-volume samples, but showed poor recovery for low-volume samples. Nylon (100 µL) and polyester swabs (27 µL) showed intermediate recovery for low-volume and excess-volume samples. Polyurethane swabs (16 µL) showed excellent recovery for all sample types. This work demonstrates that swab transfer efficiency can be affected by swab material, structure, and fluid capacity and details of the sample. Results and quantitative analysis methods from this study will assist POC assay developers in selecting appropriate swab types and transfer methods.

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.

Development of PCR assays for detection of Trichomonas vaginalis in urine specimens

Trichomonas vaginalis infections are usually asymptomatic or can result in nonspecific clinical symptoms, which makes laboratory-based detection of this protozoan parasite essential for diagnosis and treatment. We report the development of a battery of highly sensitive and specific PCR assays for detection of T. vaginalis in urine, a noninvasive specimen, and development of a protocol for differentiating among Trichomonas species that commonly infect humans.

Performance of rapid immunochromatographic assay in the diagnosis of Trichomoniasis vaginalis

Trichomonas vaginalis accounts for nearly half of all curable sexually transmitted diseases worldwide with serious health consequences. Effort to increase the sensitivity of its diagnosis is critical to both control measures and epidemiologic studies. This study was conducted to evaluate the OSOM® Trichomonas Rapid Test (Sekisui Diagnostics, Framingham, MA, USA), a qualitative antigen-detection immunochromatographic (IC) assay in the diagnosis of vaginal trichomoniasis comparable to the conventional methods. The study enrolled 258 females aged 18-50 years classified into symptomatic (185) and asymptomatic (73) groups. Vaginal swab specimens were obtained for wet mount, stained preparation (Giemsa, acridine-orange), culture (InPouch TV™, modified Diamond's), and for rapid OSOM testing. Trichomonas vaginalis was detected in 67, 66, 71, 99, 96, and 97 using wet mount, acridine-orange stain, Giemsa stain, modified Diamond's, InPouch media, and OSOM test, respectively. In comparison to a composite reference standard (CRS) of wet mount microscopy and culture, OSOM test reported 97.98%, 99.37%, 98.98%, 98.75%, and 98.84% for sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy, respectively. The OSOM test proved to be a simple and objective test. This rapid point-of-care-test will contribute significantly in the diagnosis of vaginal trichomoniasis and will increase the understanding of its still vague epidemiology.

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.

Modified Field stain - rapid viability test for Trichomonas vaginalis

AIMS

We previously reported that Modified Field Stain (MF) can be used as a rapid stain for diagnosis. In the present study we extend the observation to include the stain as an alternative method to assess viability of the cells.

METHODS AND RESULTS

Six isolates of Trichomonas vaginalis were used to assess the utility of the Modified Field stain as a rapid viability test for T. vaginalis and to compare with 0·4% Trypan Blue dye exclusion test in three conditions; normal in vitro culture growth using Hollander medium, lysed in distilled water and treated with metronidazole. MF stain showed similar growth profile pattern as Trypan Blue dye exclusion for identifying viable cells of T. vaginalis. Although, Trypan Blue dye exclusion test is ready made, rapid and widely used in laboratory as reliable viability assay, however, the limitation using Trypan Blue is the dye was unable to show internal morphological changes during the parasite's transition from being viable to non-viable. On day 3 where cultures peaked the correlation factor of both assays done to assess the viability of parasites harvested from the controls, metronidazole and distilled water treated parasites were more than 0·9 respectively.

CONCLUSIONS

This confirms that MF staining does not only record permanently the morphological changes and retain internal structural details but also provides a reliable and rapid viability assay for the parasites.

SIGNIFICANCE AND IMPACT OF THE STUDY

Therefore, in our study, Modified Field's stain may offer the researchers and laboratory technologists the opportunity to get the result on the same day and the most important thing is the ability to differentiate between viable and non-viable of T. vaginalis under three different conditions (normal culture, drug and distilled water condition). Modified Field's staining method enhanced the morphological identification of T. vaginalis compared to Trypan Blue dye exclusion.

Modified Field's staining--a rapid stain for Trichomonas vaginalis

Trichomonas vaginalis, a flagellate protozoan parasite commonly found in the human genitourinary tract, is transmitted primarily by sexual intercourse. Diagnosis is usually by in vitro culture method and staining with Giemsa stain. There are laboratories that use Gram stain as well. We compared the use of modified Field's (MF), Giemsa, and Gram stains on 2 axenic and xenic isolates of T. vaginalis, respectively. Three smears from every sediment of spun cultures of all 4 isolates were stained, respectively, with each of the stains. We showed that MF staining, apart from being a rapid stain (20 s), confers sharper staining contrast, which differentiates the nucleus and the cytoplasm of the organism when compared to Giemsa and Gram staining especially on parasites from spiked urine samples. The alternative staining procedure offers in a diagnostic setting a rapid stain that can easily visualize the parasite with sharp contrasting characteristics between organelles especially the nucleus and cytoplasm. Vacuoles are more clearly visible in parasites stained with MF than when stained with Giemsa.

Newly defined conditions for the in vitro cultivation and cryopreservation of Dientamoeba fragilis: new techniques set to fast track molecular studies on this organism

Dientamoeba fragilis is a pathogen of the human gastrointestinal tract that is a common cause of diarrhoea. A paucity of knowledge on the in vitro cultivation and cryopreservation of Dientamoeba has meant that few studies have been conducted to investigate its biology. The objective of this study was to define, for the first time, in vitro culture conditions able to support the long-term in vitro growth of Dientamoeba. Also, we aimed to define a suitable method for cryopreserving viable Dientamoeba trophozoites. A modified BD medium, TYGM-9, Loeffler's slope medium, Robinson's medium, Medium 199, Trichosel and a Tritrichomonas fetus medium were compared, using cell counts, for their ability to support the growth of D. fragilis at various temperatures and atmospheric conditions. Loeffler's slope medium supported significantly better growth compared to other media. A temperature of 42°C and a microaerophilic atmosphere were also optimum for Dientamoeba growth. To our knowledge, this is the first study to describe and compare different culture media and conditions for the growth of clinical isolates of D. fragilis. This new technology will aid the development of diagnostics for dientamoebiasis as well as facilitate large-scale sequencing projects that will fast track molecular studies on D. fragilis.

Molecular Diagnostics and Comparative Genomics in Clinical Microbiology

Initially, the availability of molecular diagnostics was considered a panacea, but replacement of conventional tests for detection and identification of microorganisms by molecular procedures eventually gathered momentum. This chapter describes current state-of-the-art molecular diagnostics and comparative genomics in medical microbiology to provide an understanding of infectious disease over the coming years. Nucleic acid-based tests are being introduced with increasing speed into routine clinical microbiology laboratories. Some of the problems remaining to be solved prior to general acceptance of nucleic acid-mediated detection and identification of microbial pathogens are reviewed. Historic objections are slowly being taken apart, and an accelerated introduction of molecular diagnostics is being pursued in many cases. Clear improvement in clinical testing is achieved by introducing molecular tests. Therefore, swift introduction of such tests into clinical practice is important to be pursued. Several PCR tests show increased sensitivity, excellent specificity, and cost effectiveness highlighting the success of the novel applications in the field of bacterial infections. Finally, some of the problems remaining to be solved prior to general acceptation of nucleic acid-mediated detection and identification of microbial pathogens are also reviewed.

Current issues and considerations regarding trichomoniasis and human immunodeficiency virus in African-Americans

Trichomonas vaginalis has long been recognized as one of the most prevalent sexually transmitted infections. However, it is only in recent years that it has been appreciated that Trichomonas may play a critical role in amplifying human immunodeficiency virus (HIV) transmission. Given the evidence that T. vaginalis likely promotes HIV infection, the apparent high level of Trichomonas infection in the African-American community is cause for concern. Even if T. vaginalis increases the risk of HIV transmission by a small or modest amount, it translates into a sizable population effect since Trichomonas is so common in this community. Therefore, control of trichomoniasis may represent an important avenue of control for the prevention of HIV transmission, particularly among African-Americans.

Nucleic-acid amplification testing of urine vs. patient complaint-driven evaluation

The present pilot study compared the ability of a conventional patient complaint-driven approach to that of nucleic-acid amplification testing (NAAT) of urine to identify those individuals among an adult, urban, Emergency Department (ED) population infected with Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV). Urine for NAAT was collected for testing after individuals had completed a questionnaire and before being seen by a physician. A total of 614 subjects were enrolled, and complete physical examinations were performed on 348 (56.6%) individuals, with women being significantly more likely to receive such an evaluation (odds ratio [OR] 3.09; 95% confidence interval [CI] 1.96-4.86); p < 0.001). A total of 153 (24.9%) of the study cohort tested positive for a least one sexually transmitted disease (STD), and only a reported history of STD (OR 1.74; 95% CI (1.18-2.57); p = 0.005) and a history of a new sexual partner in the last 3 months (OR 1.79; 95% CI 1.13-2.82); p = 0.012) were predictive of a positive STD test. NAAT of urine samples on patients who did not receive a complete physical examination resulted in a 33% (51/153) increase in diagnostic yield in this cohort of ED attendees.

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.

Definition and classification of abnormal vaginal flora

Studying the vaginal microflora is not only fascinating, with many discoveries to be made, it is also a very practical way to help women get rid of bothersome and sometimes dangerous infections. Gram-stained vaginal preparations, Pap smears, specific cultures, and nucleic acid detection techniques can be used to diagnose the constituents of the vaginal flora, but in trained hands office-based microscopy of a fresh vaginal smear, preferably using a x400 magnification phase-contrast microscope, allows almost every diagnosis and combination of diagnoses imaginable. In this chapter I will address the pros and cons of the tools that are in use to study vaginal flora, and discuss the different types of bacterial flora and the difficulties encountered in reaching the correct diagnosis of pathological conditions. The 'intermediate flora' is addressed separately, and a new entity--'aerobic vaginitis'--is discussed. Future research should focus on the interaction between infecting microorganisms and host defence mechanisms, as both together generate the pathogenicity of these conditions.

Trichomoniasis and bacterial vaginosis in pregnancy: inadequately managed with the syndromic approach

OBJECTIVE

To measure the prevalence of Trichomonas vaginalis (TV) infection and bacterial vaginosis (BV) among pregnant women in Botswana, and to evaluate the syndromic approach and alternative management strategies for these conditions in pregnancy.

METHODS

In a cross-sectional study, 703 antenatal care attendees were interviewed and examined, and specimens were collected to identify TV, BV, Candida species, Chlamydia trachomatis and Neisseria gonorrhoeae. Information on reproductive tract infections earlier in pregnancy was obtained from a structured interview and the antenatal record.

FINDINGS

TV was found in 19% and BV in 38% of the attendees. Three-fourths of women with TV or BV were asymptomatic. Syndromic management according to the vaginal discharge algorithm would lead to substantial under-diagnosis and over-treatment of TV and BV. Signs of vaginal discharge were more predictive of the presence of these conditions than were symptoms. Among the 546 attendees on a repeat antenatal visit, 142 (26%) had been diagnosed with vaginal discharge earlier in their pregnancy--14 of them twice. In 143 cases, an attendee was diagnosed with vaginal discharge in the second or third trimester; however, metronidazole had been prescribed only 17 times (12%).

CONCLUSION

Diagnosis and treatment of TV and BV among pregnant women in sub-Saharan Africa presents major challenges. Half the pregnant women in this study were diagnosed with TV or BV, but these conditions were not detected and treated during antenatal care with syndromic management. Also, health workers did not adhere to treatment guidelines. These results indicate that management guidelines for TV and BV in antenatal care should be revised.

Comparison of a TaqMan-based real-time polymerase chain reaction with conventional tests for the detection of Trichomonas vaginalis

OBJECTIVE

To compare a TaqMan-based real-time polymerase chain reaction (PCR) with conventional PCR, culture, and wet-mount microscopy for the diagnosis of trichomoniasis in women.

METHODS

Vaginal swabs from 119 women were tested for Trichomonas vaginalis by wet mount and culture. Paired vaginal lavage and urine specimens were tested by conventional and real-time PCR.

RESULTS

Using an expanded "gold standard", defined as a positive culture result using vaginal swabs and/or a positive PCR test using TVK3/7 primers, the overall prevalence of T vaginalis in the study population was 65.5% (78/119). The detection rate of T vaginalis was 65.5% (78/119) and 36.9% (44/119) by conventional PCR using vaginal washings and urine specimens, respectively; 68.9% (82/119) by real-time PCR using vaginal washings and 61.3% (73/119) by real-time PCR using urine specimens. The sensitivities of conventional PCR using vaginal washings and urine and real-time PCR using vaginal washings and urine, compared with the gold standard were 100%, 56.4%, 100% and 76.7%, and the specificities of these tests were 100%, 97.6%, 82.9% and 97%, respectively.

CONCLUSIONS

The real-time PCR test proved to be significantly more sensitive than culture and wet-mount microscopy, although its specificity was slightly lower than these tests. In addition, it was more sensitive, rapid and less time consuming than conventional PCR for the detection of T vaginalis.

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.

Viability of Trichomonas vaginalis in urine: epidemiologic and clinical implications

The impact of the viability of Trichomonas vaginalis in urine on wet mount, culture, and PCR methods was assessed. To minimize the chance of false-negative results, urine specimens should be processed within 30 min of specimen collection and maintained at 37 degrees C, since temperature appears to affect the viability of Trichomonas.

Use of an adaptation of a commercially available PCR assay aimed at diagnosis of chlamydia and gonorrhea to detect Trichomonas vaginalis in urogenital specimens

Trichomonas vaginalis PCR using reagents from a commercially available assay for Chlamydia trachomatis and Neisseria gonorrhoeae was evaluated for detection of infection in women and men attending a sexually transmitted disease clinic. Evaluations included three primer sets, endocervical swabs, vaginal swabs and urine, and various storage conditions. The TVK3/TVK7 primer set was optimal in our hands with sensitivities ranging from 69.5 to 96.8%. In all comparisons, T. vaginalis PCR performed better than routine diagnostics using microscopy for women and culture for men (P > 0.05). The assay performed well for all sample types tested, and vaginal swabs were stable for up to 7 days at ambient temperature. Using samples prepared for, and reagents from, the C. trachomatis-N. gonorrhoeae PCR assay allowed incorporation of T. vaginalis PCR diagnosis into routine clinical testing.

Kinetics of immunoglobulin G, M, A and IgG subclass responses in experimental intravaginal trichomoniasis: prominence of IgG1 response

Trichomoniasis, the most common nonviral sexually transmitted disease, is caused by infection with the protist Trichomonas vaginalis. The clinical spectrum varies from an asymptomatic state to mild, moderate or severe symptoms. However, the exact factors leading to varied symptomatology have not been well elucidated. The mouse is a useful experimental model for intravaginal trichomoniasis, for understanding the role of local immune responses in the pathogenesis and varied symptomatology of this disease. The present study reports anti-Trichomonas IgG, IgM, IgA and IgG subclass antibody responses on different post-infection days (3rd, 7th, 14th, 21st and 28th) in serum and vaginal washes of mice infected intravaginally with T. vaginalis isolates from 15 symptomatic and 15 asymptomatic women. Successful intravaginal infection was established by inoculating T. vaginalis in BALB/c mice pre-inoculated with Lactobacillus acidophilus and pretreated with oestradiol. A significant increase in parasite load was observed on the 14th post-infection day (p.i.d.) in mice inoculated with T. vaginalis isolates from symptomatic women as compared to asymptomatic women (P < 0.001), followed by reduction until the 28th p.i.d. (P < 0.05). A significant increase in specific IgG (P < 0.001) and in particular IgG1 (P < 0.001) and IgM (P < 0.01) responses was observed on the 14th p.i.d. in serum and vaginal washes of mice infected with T. vaginalis isolates from symptomatic women as compared to asymptomatic women. Significant increases in specific IgG, IgM and IgG1 responses was observed on the 14th p.i.d. in serum samples as compared with vaginal washes of mice infected with T. vaginalis isolates from symptomatic and asymptomatic women (P < 0.01), whereas no significant difference was observed in IgA, IgG2a, IgG2b and IgG3 antibody responses. The study indicates that specific IgG, particularly IgG1 and IgM, may be playing a role in establishing symptomatic infection.

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.

Increased sensitivity of Trichomonas vaginalis isolation from vaginal secretions by subsequent blind passage of preliminary negative cultures

Trichomonas vaginalis is a vaginal protozoon causing the most prevalent nonviral sexually transmitted disease. Culture is considered as the most reliable and gold standard among conventional diagnostic methods in the detection of T. vaginalis. In the present study, the diagnostic effect of subsequent blind culturing of vaginal secretion samples in Diamond's complete medium at every 48 h was investigated in 93 women. Vaginal secretion samples were examined by wet mount and inoculated into Diamond's complete medium. All tubes were subcultured to a new culture tube blindly 5 times at 48-h interval and checked microscopically everyday for the presence of T. vaginalis trophozoites. Three of 93 women were found to be positive both by wet mount and standard culture methods. Five more positive results were detected with subsequent blind culturing among 90 negative results. This system appears to be a useful method for the detection of T. vaginalis.

Laboratory investigation: Sexually transmitted diseases

Sexually transmitted diseases are among the most common infectious diseases and pose a major public health concern globally. Unfortunately, such diseases are often asymptomatic, and are left untreated for long periods of time-resulting in significant health care costs and morbidity rates. In recent years, the advancement in diagnostic testing has been tremendous, especially at the molecular level of disease. In the paper to follow, we will attempt to examine diagnostic techniques traditionally used (microscopic examination and culture) to identify STDs and compare them to newly introduced techniques (including DNA amplification and hybridization) that provide higher sensitivity and specificity, as well as shorter result reporting time.

Targeted screening for Trichomonas vaginalis with culture using a two-step method in women presenting for STD evaluation

OBJECTIVES

Trichomonas vaginalis is the most common nonviral sexually transmitted pathogen. Wet mount microscopy performs poorly compared with culture; however, universal screening using culture would be cost-prohibitive.

GOAL

The goal of this study was to develop a predictive model for wet mount-negative women who may benefit from targeted use of culture for T. vaginalis detection.

STUDY

Women presenting for sexually transmitted disease evaluation were prospectively screened for trichomoniasis using wet mount and culture. Multivariate logistic regression was used to identify predictors of culture-proven trichomoniasis among wet mount-negative women.

RESULTS

A total of 2194 women were screened for trichomoniasis; overall, the prevalence of T. vaginalis was 17.5%. Three predictors (any drug use, contact to trichomoniasis, and African-American race) provided the most specific model (100%); any 1 predictor, the most sensitive model (97.8%).

CONCLUSIONS

Given the public health impact of trichomoniasis, we recommend using any 1 of 3 predictors to identify women who would benefit from targeted culture for T. vaginalis.

Trichomoniasis

Trichomoniasis is perhaps the most common curable sexually transmitted disease worldwide, yet few resources are devoted to its control. It is associated with potentially serious complications such as preterm birth and human immunodeficiency virus acquisition and transmission. The immunology of a related organism, Tritrichomonas foetus, which causes disease in cattle, has been investigated to some extent, but more work is needed for the human strain, Trichomonas vaginalis. In addition, although trichomoniasis is easily treated with oral metronidazole, there is concern that the number of strains resistant to this antibiotic are increasing, and currently no alternative is licensed in the United States. As more is appreciated concerning the important public health implications of this common infection, more work will need to be done in understanding the diagnosis, treatment, and immunology of this organism.

Evaluation of Xenostrip-Tv, a rapid diagnostic test for Trichomonas vaginalis infection

An immunochromatographic strip test, Xenostrip-Tv, was compared to wet mount and PCR for the diagnosis of Trichomonas vaginalis infection in women. Of 428 specimens tested, 54 (12.6%) were positive by an "expanded gold standard," defined as either a positive wet mount and PCR test with primers TVK3 and TVK7 and/or a positive PCR test confirmed by a second PCR assay with primers TVA5-1 and TVA6; 26 (6%) were positive by wet mount, and 36 (8.4%) were positive by Xenostrip-Tv test. Since the Xenostrip-Tv test is rapid and easy to perform and proved to be more sensitive than wet mount, it should be considered as an alternative to wet mount for point-of-care diagnosis of trichomoniasis, especially in settings where microscopy is impractical.