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The timing of
inoculation did not affect the results of the InPouch TV method for
detection of T. vaginalis.
Timing of inoculation of
the pouch makes no difference in increased detection of Trichomonas
vaginalis by the InPouch method.
Barenfanger J, Drake C, Hanson C.
Journal of Clinical Microbiology 2002; 40:1387-1389.
Summary:
Question
Is the timing of inoculation of the pouch for the InPouch TV test critical
for optimal growth and detection of T. vaginalis organisms?
Design
This study assessed the effect of timing the
inoculation of the bottom portion of the InPouch TV test for T.
vaginalis and its effect, if any, on the results of the test. The
first method was to delay inoculation of the bottom pouch until the
initial microscopic examination of the top pouch was performed. A second
method was to inoculate the bottom pouch immediately after specimen
collection. Both methods were compared to a conventional wet mount
preparation of the specimen on a glass slide.
Participants
This study included 498 women with signs
and/or symptoms of vaginitis, vaginal discharge, dysuria, dyspareuria,
and/or "strawberry" cervix who attended the hospital emergency
department and various clinics in the region of Springfield, IL, including
an urgent care center, a family practice clinic, and a women's health
center.
Description of Tests and Diagnostic
Standard
Vaginal secretions were suspended in saline
and processed by one of three methods: 1) inoculation of the top portion
of the InPouch TV test (BioMed Diagnostics, San Jose, CA) and inoculation
of the bottom pouch only after the microscopic examination of the top was
complete, regardless of the transit time, 2) inoculation of the top
portion as for method 1) with inoculation of the bottom pouch immediately.
For this method, the microscopic exam was performed on the bottom pouch
when the specimen arrived in the lab, and 3) a traditional wet preparation
in which 2 to 3 drops of each patient's secretions were placed on a glass
slide and examined microscopically. If the results of the wet prep for
methods 1) and 2) were negative, the pouches were incubated and examined
on days 2, 3, and 5. A positive result from either the wet prep or the
InPouch was considered a true positive. The transit time of the tests
varied from 4 to 570 minutes, with 68% of the tests arriving within 1
hour, and a mean time of 76 minutes.
Main Outcome Measures
The number of specimens by each inoculation
method that were positive for T. vaginalis by microscopic
examination before or after incubation were determined.
Main Results
Thirty-one of 498 specimens (6.2%) were
positive for T. vaginalis upon initial microscopic examination of
the upper pouch, regardless of the transit time. Inoculation methods 1)
and 2) produced identical results: an additional nineteen samples were
positive by either method after incubation, for a total of fifty (10.0%)
positives. These results can be compared with 36 samples (7.2%) that were
positive for T. vaginalis by microscopy using the conventional wet
prep method. Eight of the positive InPouch samples had transit times
greater than 3 hours.
Authors' Conclusions
Within the limitations of this experiment,
an immediate vs. delayed inoculation of the lower pouch did not affect the
overall performance of the InPouch for growth and detection of T.
vaginalis.
Source of funding: BioMed Diagnostics.
For correspondence: Joan Barenfanger,
Microbiology, Memorial Medical Center, Pathology Department, 701 N. First
St., Springfield, IL 62781. E-mail address: barenfanger.joan@mhsil.com.
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