|
Self-collected
vaginal swabs had the highest rate of detecting positive tests for
both C. trachomatis and N. gonorrhoeae infections.
Comparing first-void urine specimens,
self-collected vaginal swabs, and endocervical specimens to detect Chlamydia
trachomatis and Neisseria gonorrhoeae by a nucleic acid
amplification test.
Shafer M-A, Moncada J, Boyer CB, Betsinger
K, Flinn SD, Schachter J.
Journal of Clinical
Microbiology 2003;41:4395-4309.
Summary:
Question
How do first-void urine specimens, self-collected vaginal swabs, and
endocervical specimens collected from the same female patient compare for
the detection of C. trachomatis and N. gonorrhoeae using the
ligase chain reaction assay?
Design
This study describes a direct comparison of the results of a ligase chain
reaction assay for C. trachomatis and N. gonorrhoeae applied
to first-void urine specimens, self-collected vaginal swabs, and
clinician-collected endocervical specimens in a large cross-sectional
sample of young women in the United States on entry into the military.
Participants
Participants included 1841 sexually active women from all 50 states, Guam,
Puerto Rico, and the U.S. Virgin Islands who received a screening
reproductive health assessment as part of their recruit training at the
U.S. Marine Corps Recruiting Depot in Parris Island, S.C. The median age
was 18 years, 90% were less than 21 years old. Ninety-two percent were
unmarried, 43% were a racial or ethnic minority, and 44% reported more
than 4 lifetime partners.
Description of Tests and Diagnostic
Standard
Participants collected 20 ml of first-void urine and a vaginal swab
specimen, which was placed into a sterile tube. During a pelvic
examination, the clinician collected an endocervical specimen according to
the LCx protocol. The vaginal and urine specimens were frozen within 24 h
of collection, and the endocervical specimen was kept cold and processed
within 6 h of collection. All specimens were processed and tested for C.
trachomatis and N. gonorrhoeae using LCx system protocols
(Abbott Laboratories). Most specimens were analyzed before February 1,
2001. The eleven positive specimens among the 178 tested after February 1,
2001 were considered confirmed positive if the repeat specimen-to-cutoff
ratio was >1.0 on retesting.
Main Outcome Measures
This study compares three different specimen collection sites (endocervical,
self-collected vaginal, and urine) to identify a positive C.
trachomatis or N. gonorrhoeae test. Collection site
performances were determined using any positive test by any collection
method as a true positive.
Main Results
Among all specimens tested, the proportion of patients positive for C.
trachomatis and N. gonorrhoeae was 11.6% and 2.4%,
respectively. Positive results by specimen type are shown in the table.
Combining the urine specimen with the vaginal specimen boosted the
detection rate of C. trachomatis to 94%. Combining the vaginal
specimen with the endocervical specimen boosted the detection rate of N.
gonorrhoeae to 93%.
Authors' Conclusions
The self-collected vaginal specimen ranked
highest in the ability to detect a positive result among any of the three
types of specimen collection for both C. trachomatis and N.
gonorrhoeae. There was an improvement in the identification of
positive results when more than one method was used to screen.
Source of funding:
Department of Defense grant under the Women's Health Initiative, and in
part by the Leadership Education in Adolescent Health, Maternal and Child
Health Bureau
For correspondence:
Mary-Ann Shafer, Division of Adolescent Medicine, Department of
Pediatrics, University of California, San Francisco, 3333 California Ave.,
Suite 245, Box 0503, San Francisco, CA 94143. E-mail address: shafer@itsa.ucsf.edu.
|
.gif){kind=small}