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Synthetic
peptide-based EIA assays are able to detect species-specific C.
trachomatis antibodies.
Sensitivity and
specificity of three new commercially available Chlamydia
trachomatis tests.
Verkooyen RP, Peeters MF, van
Rijsoort-Vos JH, van der Meijden WI, Mouton JW.
Inter J STD AIDS. 2002;13(Suppl 2):23-25.
Summary:
Question
How well do three commercially available serological assays perform for
the diagnosis of C. trachomatis infections in various study
populations?
Design
This study describes the evaluation of three ELISA assays for the
detection of C. trachomatis-specific IgG and IgA antibodies in sera
from patients with either a proven C. pneumoniae infection, with a
proven C. trachomatis infection, or from the general population.
Participants
Four groups of patients were studied. Group 1 consisted of 443 blood
donors visiting a transfusion center in The Netherlands. Group 2 consisted
of 22 patients with proven C. pneumoniae infection from whom three
consecutive serum samples were available. Group 3 consisted of 324
patients visiting an STD clinic in The Netherlands, with C. trachomatis
infection detected by COBAS Amplicor PCR (Roche Diagnostic Systems). Group
4 consisted of 100 patients visiting the STD clinic with negative PCR
results.
Description of Tests and Diagnostic
Standard
Three commercially available, synthetic peptide-based ELISA assays for
detection of C. trachomatis IgG and IgA were used: the pELISA (Medac,
Hamburg, Germany), the EIA (Labsystems, Helsinki, Finland), and the SeroCT
(Savyon, Be'er-Sheva, Israel). All assays were used following the
manufacturers' instructions.
Main Outcome Measures
The prevalence of C. trachomatis IgG and IgA antibodies in each
patient group, detected by each assay, were compared with each other. The
age prevalence of positive results was determined in Group 1 and the
sensitivity of the assays compared to detection of C. trachomatis
by PCR was determined for Group 3.
Main Results
The prevalence of IgG and IgA antibodies detected by each assay in each
patient group is shown in the table. For all three tests, there was a
negative correlation between prevalence and age in patients from Group 1.
For the patients in Group 2, there was no increase in titer in the second
and third serum samples. The sensitivity of the three assays for patients
in Group 3 was around 70% for IgG and less than 50% for IgA. The number of
patients with a negative IgG and a positive IgA result was 8, 9, and 9 for
the Labsystems, the Savyon, and the Medac assays, respectively.
| Prevalence of C.
trachomatis IgG and IgA in four patient groups using 3 assays |
| Assay1 |
Antibody |
Patient
group (% positive) |
Group 1 (n=443)
blood donors |
Group 2 (n=22)
proven
C. pneumoniae infection |
Group 3 (n=324)
C. trachomatis infection by PCR |
Group 4 (n=100)
STD patients without
C. trachomatis infection by PCR |
| CtMp |
IgA |
5 |
9 |
45 |
17 |
| CtL |
5 |
5 |
38 |
16 |
| SeroCT |
5 |
9 |
48 |
14 |
| CtMp |
IgG |
12 |
9 |
75 |
38 |
| CtL |
6 |
9 |
69 |
26 |
| SeroCT |
6 |
14 |
68 |
26 |
| 1CtMp=pELISA,
Medac; CtL=EIA, Labsystems; SeroST=Savyon |
Authors' Conclusions
Using four well-defined patient groups, both
the sensitivity and the specificity of three new peptide-based C.
trachomatis serological tests are much better than earlier tests.
These synthetic peptide-based EIA tests are able to detect
species-specific C. trachomatis antibodies, which are strongly
related to infection. However, when using these assays to determine the
presence of an active C. trachomatis infection, many cases will be
missed due to the relatively low sensitivity.
Source of funding: none given
For correspondence: R. P. Verkooyen,
Erasmus MC, Department of Medical Microbiology and Infectious Diseases,
Room L362, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
E-mail address: verkooyen@kmic.fgg.eur.nl.
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