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Several screening
algorithms did not perform well for the detection of cervical
gonococcal and chlamydial infections among female sex workers in
Indonesia.
Sexually transmitted infections among
female sex workers in Jupang, Indonesia. Searching for a screening
algorithm to detect cervical gonococcal and chlamydial infections.
Davies SC, Otto B, Partohudoyo S,
Chrisnadarmani VAMA, Neilsen GA, Ciaffi L, Patten J, Samson ET, Sutama IN.
Sexually
Transmitted Diseases 2003;30:671-679.
Summary:
Question
What is the prevalence of STIs among female sex workers in Kupang, West
Timor, and which screening algorithm performed best for the detection of
cervical gonococcal and chlamydial infections?
Design
This study describes the prevalence of STIs among female sex workers in
Kupang, and quantifies characteristics associated with cervical infection
with N. gonorrhoeae and/or C. trachomatis (NG/CT) determined
by laboratory diagnosis to evaluate algorithms based on the strongest
associations with infection.
Participants
Two hundred eighty-eight women working as independent sex workers or
associated with a brothel in Kupang, Indonesia, who were at least 15 years
old and had not taken antibiotics in the preceding two weeks, were tested.
Description of Tests and Diagnostic
Standard
Blood was collected and a speculum examination was performed on each
woman. Characteristics of vaginal discharge were noted, and swab specimens
were collected from the vaginal wall and endocervix. Trichomonas was
detected by inoculation of a vaginal swab into TV Inpouch (Biomed
Diagnostics, San Diego, CA) culture medium and incubation for up to 7
days. Trichomoniasis was defined by the presence of motile trichomonads.
Bacterial vaginosis (BV) was detected by the appearance of the vaginal
discharge, the microscopic examination of a Gram-stained vaginal smear for
clue cells, and the amine test on the vaginal discharge. BV was defined as
the presence of a thin gray-whitish homogenous vaginal discharge, a
positive amine test, and at least 20% clue cells on Gram stain. N.
gonorrhoeae was detected by Gram stain and culture onto modified
Thayer-Martin medium of a cervical swab specimen. A positive culture was
determined by the presence of oxidase positive colonies containing
Gram-negative diplococci and sugar utilization tests. C. trachomatis
was detected from an endocervical swab using the PACE-2 DNA assay (GenProbe,
San Diego, CA) according to the manufacturer's instructions. Sera were
screened for syphilis by RPR test (VD-25, Murex Diagnostics, Dartford, UK)
and positive results were confirmed by TPHA (Fujirebio, Tokyo, Japan).
Endocervical swabs were evaluated for the quantity of polymorphonuclear
leukocytes (PMNs) per microscopic high power (X1000) field (hpf).
Demographics, sexual behavior, clinical
history, and physical examination characteristics associated with NG/CT on
univariate analysis were included in a backward-selection logistic
regression model.
Main Outcome Measures
Algorithms were generated to detect NG/CT infection based on combinations
of characteristics found to have the strongest association with NG/CT that
did not rely on the calculation of a "risk score" and could be
simple and easy to use. The validity of each algorithm was evaluated by
calculating sensitivity, specificity, positive predictive value (PPV), and
negative predictive value (NPV) in comparison with the results of
laboratory tests.
Main Results
Overall, 147 (51%) of 288 women had one or more infection with N.
gonorrhoeae, C. trachomatis, T. vaginalis, or T. pallidum.
The prevalences of N. gonorrhoeae and C. trachomatis were
31% and 24%, respectively. Fourteen (4.9%) women admitted to abnormal
vaginal symptoms, 41% had features of cervicitis (mucopurulent
endocervical discharge or bleeding easily induced by cervical sampling).
Abnormal vaginal discharge was noted in 12% of women.
After logistic regression analysis, the
presence of clear cervical mucus or cervicitis, and a PMN count of >30/hfp
were significantly associated with NG/CT. The performances of several
algorithms for diagnosis of NG/CT combining the factors most strongly
associated with laboratory detection of NG/CT are shown in the table.
Several algorithms achieved >80% sensitivity but the highest
specificity was only 50%.
Authors' Conclusions
None of the algorithms tested performed well
enough to recommend. Periodic presumptive treatment should be considered
for female sex workers among whom the prevalence of STIs is high.
Source of funding:
Australian Agency for International Development, through The Indonesia
HIV/AIDS and STD Prevention and Care Project
For correspondence:
Stephen Davies, The Sutherland Hospital, Locked Mail Bag 21, Taren Point
NSW 2229, Australia. E-mail address: Stephen@daviesandco.org.
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