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Women in Madagascar
who seek primary care for genital discharge should be treated
syndromically and screened for syphilis.
Laboratory diagnosis
of sexually transmitted infections in women with genital discharge in
Madagascar: implications for primary care.
Behets FM-TF, Andriamiadana J, Randrianasolo
D, Rasamilalao D, Ratsimbazafy N, Dallabetta G, Cohen MS.
Inter J STD
AIDS. 2002;13:606-611.
Summary:
Question
Which tests and diagnostic approaches are feasible and useful in some
settings of Madagascar for the detection of sexually transmitted
infections in women with genital discharge?
Design
This study describes a direct comparison of the results of reference
assays for the detection of C. trachomatis, N. gonorrhoeae,
and T. vaginalis with those of less technical and more readily
available laboratory tests for these organisms.
Participants
Women (n=1066) presenting to two STI clinics in Antananarivo, Madagascar,
with a new episode of genital discharge, itching, or dysuria, who were at
least 18 years old, were tested.
Description of Tests and Diagnostic
Standard
A blood sample was collected for syphilis serology using rapid plasma
reagin (RPR, Becton Dickinson, Cockeysville, MD). Sera that were RPR
positive were tested using microhemagglutination for T. pallidum (TPHA,
Fujirebio, Tokyo). Women provided a first-stream urine sample for
detection of leukocytes using a dipstick test (LED, Chemstrip LN,
Biodynamics, Indianapolis, IN) and for gonococcal and chlamydial testing
using ligase chain reaction (LCR, LCx Probe System, Abbott, Laboratories,
Abbott Park, IL) following manufacturers' instructions. Wet mounts of
vaginal fluid were examined microscopically for the presence of motile
trichomonads. Gram-stained smears of cervical swabs were examined for the
presence of Gram-negative intracellular diplococci and leukocytes.
Cervical swabs were cultured on modified Thayer-Martin medium (Becton
Dickinson) and tested for chlamydia antigen using immunofluorescence (IF,
Syva MicroTrak Chlamydia trachomatis Direct specimen Test, Behring
Diagnostics Inc., Rijswijk, Netherlands). All testing was performed
locally except the LCR, which was performed at the University of North
Carolina.
Main Outcome Measures
The sensitivity, specificity, positive predictive value (PPV), and
negative predictive value (NPV) of locally performed tests for the
detection of gonococcal and chlamydial infections were determined compared
with LCR results. LED was evaluated as a marker for gonococcal, chlamydial,
and trichomonas infections.
Main Results
The results of laboratory tests are presented in table 1. The performances
of selected laboratory results to detect gonococcal and chlamydial
infection as defined by the result of the LCR test on urine are shown in
table 2. When cervical infection with N. gonorrhoeae or C.
trachomatis (determined by LCR) was grouped with trichomoniasis
(detected by wet mount), the sensitivity, specificity, PPV, and NPV of the
LED test was 64.3, 61.8, 52.6, and 72.5, respectively.
| Table 1.
Results
of laboratory tests |
| Laboratory
test |
Number
tested |
Number
(%) positive |
| RPR |
992 |
71
(7.1)* |
| LED |
1005 |
489
(48.7)** |
| Gram
stain for diplococci |
1056 |
50
(4.7) |
| Culture
for N. gonorrhoeae |
936 |
69
(7.4) |
| LCR
for N. gonorrhoeae |
1058 |
140
(13.2) |
| IF
for chlamydia antigen |
149 |
38
(25.5) |
| LCR
for C. trachomatis |
1058 |
115
(10.9) |
| Wet
mount for T. vaginalis |
1051 |
260
(24.7) |
*60 (89.5%) of 67 RPR-reactive
sera had a positive TPHA test result
**228 (22.4%) additional samples were trace reactive
|
| Table 2.
Performance by organism of selected laboratory results for detection
of gonococcal and chlamydial infections as determined by LCR |
| Organism |
Test |
Number
tested |
Parameter
(%) |
| Sensitivity |
Specificity |
PPV |
NPV |
| N. gonorrhoeae |
Gram
stain |
1049 |
22.9 |
98.0 |
64.0 |
89.2 |
| Culture |
930 |
56.9 |
99.7 |
97.0 |
94.2 |
| C. trachomatis |
IF |
149 |
75.0 |
77.3 |
15.8 |
98.2 |
| Both* |
>20
leukocytes** |
1049 |
27.8 |
81.4 |
27.9 |
81.3 |
| LED
positive |
1003 |
58.2 |
53.9 |
24.0 |
83.7 |
| LED
trace or positive |
1003 |
81.1 |
31.2 |
22.8 |
86.8 |
*The
prevalence of cervical infection due to gonococcal or chamydial
infection was 20.7%.
**Leukocytes were measured per microscopic high power field in
Gram-stained cervical smears |
Authors' Conclusions
Attempts to identify low-technology
laboratory tests that may be used as helpful surrogate markers for
gonococcal and chlamydial infections in symptomatic women were
unsuccessful. The infections were not associated with either the presence
of at least 20 leukocytes per high power field in endocervical smears or
reactive LED in urine. Women who seek primary care for genital discharge
should be treated syndromically and tested for syphilis.
Source of funding: US Agency for
International Development through Futures Group International and Family
Health International
For correspondence: Frieda Behets,
2102A McGavran-Greenberg Hall, CB 7435, Chapel Hill, NC 27599-7400. Email
address: frieda_behets@unc.edu.
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