Prevalence of Trichomonas vaginalis infection among Egyptian women using culture and Latex agglutination: cross-sectional study

Abstract

Background: This is a cross-sectional study carried out in the Obstetrics and Gynecology Department at Kasr Al- Ainy Cairo University Hospitals.

Methods: One thousand female patients in the child bearing period (age 18-45 yrs) were included in this study. These females were non-pregnant and non-menstruating with no douching or intercourse for at least 2-3 days, no use of antibiotics, anti-protozoal or steroids for the past 15 days complaining of vaginal discharge with or without itching, burning sensation or both. Vaginal swabs were obtained from all patients for examination by direct wet mount examination, Giemsa staining, Modified Diamond culture and latex agglutination test Kalon) to detect the presence of Trichomonas vaginalis infection.

Results: The prevalence of trichomonas infection was 50 cases, latex agglutination test detected 50 positive cases, 30 of which were also positive by culture, and only 10 were detected both by Giemsa staining and by wet mount. The wet mount, Giemsa staining and Kalon latex test had sensitivities of 33.3, 33.3% and 100% respectively while their specificities were 100%, 100% and 97.9% respectively.

Conclusion: Screening tests should be done routinely to depict cases of T. vaginalis infection and should be included in the control programs of sexually transmitted infections. Although wet mount is not a sensitive method for diagnosis of T. vaginalis yet, it is a good positive one. Staining is only useful when there is heavy T. vaginalis infection. Latex agglutination is a highly sensitive, simple, rapid and cost effective test. It provides results within 2-3 minutes and it has the potential for use in screening and diagnosis of T. vaginalis infection.

Figure 1

T. vaginalis in fresh wet mount examination × 40. The wet preparation of the vaginal discharge was made immediately, by applying a drop from the sample to a small area of a clean glass slide with a cover slip in order not to trap air bubbles. The whole smear was examined using conventional light microscopy for motile Trichomonas vaginalis with low power objective (× 10), then with high power objective (× 40). If motile flagellates with characteristic motility (jerky movement) and morphology of trichomonads were seen, the specimen was reported as positive for T. vaginalis. If no flagellated organisms were seen, the specimen was reported as negative for T. vaginalis. The test is dependent on demonstrating the motility of T. vaginalis that loses their motility rapidly after leaving the vaginal environment. Wet mount examination was performed within less than half an hour of collection in order to get optimal results and was held at room temperature. The T. vaginalis trophozoite is the oval as well as flagellated, or “pear” shaped as seen on a wet-mount.

Figure 2

T. vaginalis after staining with GIEMSA stain × 100. For Giemsa stain, the vaginal smear was applied to a small area of a clean microscope slide,then allowed to air-dry before fixing it with methanol for about 1 minute and left to dry again. Then, the slide was placed in 20% Giemsa stain for 20 minutes. The slide was then rinsed with buffered water to remove excess stain and then left to dry(no cover slip applied). The stained preparations were examined under the light microscope with oil immersion objective (100 ×) to detect the trophozoites of Trichomonas vaginalis.

Figure 3

T. vaginalis in Modified Diamond culture × 40. Before inoculation, the culture tubes were removed from −20°C and incubated at 37°C for 1 to 2 hours to bring prepared medium at room temperature. Directly, the swab was inserted into the culture tubes containing the modified Diamond's medium. The tubes containing the inoculated medium were incubated vertically at 37°C in 5% CO2. The culture was examined daily using binocular or inverted microscope for the presence of T. vaginalis trophozoites. Aseptically, drop of the deposit was removed using a sterile pipette and placed on a slide and covered with a glass cover slip for wet mount examination. Examination was done under I0×-40× magnification. If the organism was not seen, the culture was incubated again for up to 1 week, with daily examination or every other day in the same manner. If no trichomonads were seen, the specimen was considered negative and discarded.