1. Evaluation of the OSOM Trichomonas Rapid Antigen Test versus
Microscopic Wet Mounts in a Public Health Clinic
Amy Bauera, Amanda Garnera, Kristen Ramseiera, Thomas Huberb
a Brazos County Health Department b Central Texas Veterans Health Care System VA Hospital
+ -
+ 15 21
- 0 286
Wet Mount Microscopy
OSOM®
Trichomonas
Rapid Test
(vaginal swab)
Total 15 307 322
Total
36
286
Sensitivity: 15/15 = 100%
Specificity: 286/307 = 93%
Agreement: 301/322 = 94%
Technician
Number of
Tests
Performed
Cases of
Trichomonas Not
Identified on Wet
Mount
Average Time Added
to Final Results
Reporting Due to
Rapid Test
Time Range
#1 100 10 -1.46 min. -13 to +7 min.
#2 89 3 +1.70 min. -8 to +6 min.
#3 111 6 +2.96 min. -11 to +9 min.
#4 22 2 +1.27 min. -8 to +7 min.
Sample & Methods
Participants
- Women presenting to STI Clinic that had vaginal specimens
collected.
- 322 specimens were collected and used in the comparison study at no
extra charge to the patients.
- Women ranged in age from 14 – 61 years old.
- The ethnic backgrounds of the patients included Caucasian,
Hispanic, Asian, African American, and those of mixed ethnicity.
- Specimens were collected and compared over a six month period
from January 1 through June 30.
Clinic Background
- Females attending STI Clinic are routinely checked for HIV, syphilis,
Trichomonas infections, yeast infections, bacterial vaginosis,
gonorrhea, and chlamydia.
- Results from HIV (if rapid test performed), Trichomonas, yeast, and
bacterial vaginosis testing are available to the patient prior to leaving
clinic, and usually within 20 minutes of the patient seeing the provider.
- Results from gonorrhea cultures are available in 48 hours, syphilis in
24 hours, and confirmatory testing for gonorrhea, chlamydia, and HIV
testing typically within 7 days as these tests are sent out to a reference
laboratory.
- Herpes and Hepatitis C testing is also available for an additional fee.
Results
The OSOM® Trichomonas Rapid Test detected trichomonas antigen in 36
vaginal specimens that presented during clinic. Of those 36 positive
specimens, only 15 were detected by traditional wet mount microscopy.
The OSOM® test detected antigen in an additional 21 specimens in
which the wet mount was negative, and would have otherwise been
missed and left the patient untreated (see table 1).
After assessing the times across all 322 patients who had the OSOM®
Trichomonas Rapid Test performed, the rapid test added an average of 68
seconds to the processing of each female specimen in the laboratory (see
table 2).
Discussion
The OSOM® Trichomonas Rapid Test more than doubled the number
of trichomoniasis diagnoses in our clinic patients over the six months the
study took place. This increase in diagnosis has been done without
significantly increasing turnaround times. We find the greater turnaround
time is negligible when considering the improved care we are now
providing to our patients.
Our conclusions are similar to those of the Calgary Laboratory Services
study (Campbell et. al., 2008). Since the OSOM® Trichomonas Rapid
Test requires very little hands-on time, the lab technicians are able to
dedicate that time to performing other tests while the antigen is
incubating. The test also decreased the amount of time devoted to wet
mount microscopy. Although the cost of the OSOM® Trichomonas Rapid
Antigen Test is more than the materials required for wet prep
microscopy, we feel that it is justified by the improved detection of T.
vaginalis.
The increased detection of T. vaginalis during our STI clinics has far
reaching health, social, and economic benefits for the population we
serve. Women who test positive due to the implementation of the
OSOM® Trichomonas Rapid Test are receiving care earlier than they
would have in the past. This may lead to reduced clinic visits due to a
missed diagnosis, reduced chance of spreading the disease to partners,
and a reduced chance of complications from an untreated infection.
Women who may be newly infected will also be able to be identified
earlier as the rapid test requires ¼ of the organisms/mL of the wet mount
to be present in order to be diagnosed positive.
While we have adequate resources and trained staff to properly examine
wet mount slides for T. vaginalis, the OSOM® Trichomonas Rapid Test
detects positive cases at a rate comparable to culture, which would be
useful for facilities lacking microscopic and culture capabilities (Khatoon
et. al., 2015).
Factors that may have influenced turnaround time include needing
clarification from the nurses on specimens, specimens being delivered
that were not properly prepared, excessively busy clinics that resulted in
specimens backing up in the laboratory, and the availability of only one
microscope to read wet mounts. While all of these factors may have
contributed to the turnaround time, we feel that none of them were
significant enough to alter our data in any meaningful way.
We have instituted the OSOM® Trichomonas Rapid Test during our STI
clinics and discontinued microscopic wet mounts.
Table 1
Table 2
Materials & Procedure
References
Bauer A., Garner A. STD Clinic Procedures. Bryan: Brazos County Health Department, 2014. Print.
Campbell, L., Woods, V., Lloyd, T., Elsayed, S., Church, D. L. “Evaluation of the OSOM Trichomonas Rapid Test versus Wet Preparation
Examination for Detection of Trichomonas vaginalis Vaginitis in Specimens from Women with a Low Prevalence of Infection.” Journal of
Clinical Microbiology 46.10 (2008): 3467-3469. Print.
Gerbase, A.C., Rowley, J.T., Heymann, D.H.L., Berkley, S.F.B., Piot, P. “Global prevalence and incidence estimates of selected curable STDs.”
Sexually Transmitted Infections 74.Suppl 1 (1998): S12-S16. Print.
Khatoon, R., Jahan, N., Ahmad, S., Khan, H. M., Rabbani, T. “Comparison of four diagnostic techniques for detection of Trichomonas vaginalis
infection in females attending tertiary care hospital of North India.” Indian Journal of Pathology and Microbiology 58.1 (2015): 36-39. Print.
Ohlemeyer, C. L., Hornberger, L. L., Lynch, D. A., Swierkosz, E. M. “Diagnosis of Trichomonas vaginalis in Adolescent Females: InPouch TV®
Culture Versus Wet-Mount Microscopy.” Journal of Adolescent Health 22.3 (1998): 205-208. Print.
Secor, W. E., Meites, E., Starr, M. C., Workowski, K. A. “Neglected Parasitic Infections in the United States: Trichomoniasis.” The American
Journal of Tropical Medicine and Hygiene 90.5 (2014): 800-804. Print.
Sekisui Diagnostics. OSOM® Trichomonas Rapid Test Package Insert. San Diego: Sekisui Diagnostics, LLC, 2013. Print.
“Trichomoniasis - CDC Fact Sheet.” CDC. CDC, 28 April 2015. Web. 14 August 2015.
Photo 1 Photo 2
Materials
- OSOM® Trichomonas Rapid Test Kit
- Microscope
- Slides
- Gram Stain Kit
- Vaginal Swabs
- Timers
Procedure
- Females at clinic first talked to a nurse to have their medical history
recorded along with their primary reason for visiting clinic. If
requested, blood was drawn at this time for HIV and syphilis testing.
- They then entered an exam room where the provider screened them
and collected one cervical swab for GC/CT testing and a GC culture
plate, one vaginal swab for a gram stain, wet mount, and KOH slide
for yeast identification, and one vaginal swab for the OSOM®
Trichomonas Rapid Test.
- The specimens were delivered to the laboratory by the provider within
5-10 minutes of collection, where they were examined by the
technicians.
- The rapid test was run simultaneously as the slides were being
reviewed, but out of sight of the technician reading the slides so they
did not know the result of the rapid test.
- The rapid test was started as soon as the specimens arrived in the
laboratory. Often the rapid test was started prior to wet mount slide
review as there may have been other specimens being reviewed by the
technician utilizing the microscope.
- When the technician finished reviewing the slides, they recorded the
results along with the time they finished.
- As the technician was reading the slides, a second technician was
monitoring the rapid test. If the test indicated a positive result, the
technician recorded the time it appeared. If the test remained negative,
it was left to incubate for the full ten minutes as required by the kit in
order to call a negative result. At which point, that time was recorded.
- The time difference between the end of the rapid test and the end of
slide review was calculated for each patient to see how much (if any)
the rapid test delayed the final report during clinic.
- Photos 1 and 2 are examples of how the rapid test was setup and
processed during STI clinic.
Introduction
Sexually transmitted diseases are among the most common causes of
illness in the world, and have far reaching health, social, and economic
consequences. Many of these infections can lead to serious
complications, “and a number of STDs have been identified as
facilitating the spread of HIV” (Gerbase et al., 1998).
Trichomoniasis is a common sexually transmitted disease with women
more likely to be infected than men. While it’s considered the most
common curable STD, only around 30% of people ever develop any
symptoms of trichomoniasis. (CDC.gov)
Infection is most commonly diagnosed by identifying the motile parasite
during microscopic examination (wet mount), but the sensitivity of wet
mount is generally poor (51-65%) (Secor et al., 2014).
Ohlemeyer et al., 1998, discuss that wet mounts may be misread due to a
variety of factors including a prolonged period between the exam and the
reading, or a low concentration of the organisms in the sample. Wet
mount diagnosis of trichomoniasis requires a large concentration of
organisms (10,000/mL).
The OSOM® Trichomonas Rapid Test detects Trichomonas antigen in
vaginal swabs in 10 minutes (or less if positive). It can detect antigen
derived from as few as 2,500 organisms/mL, which is a lower
concentration than expected in the vaginal discharge of most positive
patients (OSOM® package insert). We decided to evaluate the OSOM®
test to see if it was more sensitive than wet mounts during our clinics,
and to see if it delayed the final laboratory report for the waiting patient