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Journal of Clinical Microbiology, March 2000, p. 1105-1112, Vol. 38, No. 3
Indiana University School of Medicine,
Indianapolis, Indiana1; National
Institute of Allergy and Infectious Diseases, National Institutes of
Health, Bethesda,2 and Johns Hopkins
University, Baltimore,3 Maryland;
University of California-San Francisco, San Francisco,
California4; Thomas Jefferson University
Hospital, Pittsburgh, Pennsylvania5;
Louisiana State University,6 and
City of New Orleans' Delgado
Clinic,7 New Orleans, Louisiana; and
University of Texas Medical Branch, Galveston,
Texas8
Received 27 September 1999/Returned for modification 22 November
1999/Accepted 24 December 1999
The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR
CT/NG tests were evaluated in a multicenter trial for the ability to
detect Chlamydia trachomatis infections. Test performance compared to that of culture was evaluated for 2,236 matched
endocervical swab and urine specimens obtained from women and for 1,940 matched urethral swab and urine specimens obtained from men.
Culture-negative, PCR-positive specimens that tested positive in a
direct fluorescent-antibody test or in a confirmatory PCR test for an
alternative target sequence were resolved as true positives. The
overall prevalences of chlamydia were 2.4% in women and 7.2% in men.
The COBAS AMPLICOR and AMPLICOR formats yielded concordant results for
98.1% of the specimens. With the infected patient as the reference
standard, the resolved sensitivities of COBAS AMPLICOR were 89.7% for
endocervical swab specimens, 89.2% for female urine specimens, 88.6%
for male urethral swab specimens, and 90.3% for male urine specimens.
When results were analyzed as if only a single test had been performed
on a single specimen type, the resolved sensitivity was always higher. The resolved specificities of PCR were 99.4% for endocervical swab
specimens, 99.0% for female urine specimens, 98.7% for male urethral
swab specimens, and 98.4% for male urine specimens. The internal
control revealed that 2.4% of the specimens were inhibitory when
initially tested. Nevertheless, valid results were obtained for 98.6%
of the specimens because 59.1% of the inhibitory specimens were not
inhibitory when a second aliquot was tested. The COBAS AMPLICOR and
AMPLICOR CT/NG tests for C. trachomatis exhibited equally
high sensitivity and specificity with both urogenital swab and urine
specimens and thus are well suited for screening for C. trachomatis infection.
According to the World Health
Organization, approximately 89 million new Chlamydia
trachomatis infections occur annually worldwide (http://www.who.ch/programmes/asd/facsheet.htm). Chlamydia
screening programs decrease the prevalence of chlamydia infection
(6, 24) and reduce the incidence of pelvic inflammatory
disease (30). Economic modeling studies suggest that the
savings resulting from the prevention of long-term sequelae more than
compensate for the cost of screening for and treating infections
(18).
Diagnosis remains a challenge because C. trachomatis
infections are often asymptomatic, especially in women. Recent studies have shown that nucleic acid amplification-based tests are ideally suited for screening. Unlike conventional tests, they exhibit high
sensitivity and specificity for the detection of C. trachomatis in noninvasively collected specimens (3, 11, 14,
17, 28, 31, 35). Testing of such samples should encourage
asymptomatic individuals in at-risk populations to undergo screening
and should reduce the costs associated with specimen collection.
Ideally, high-risk populations such as adolescents should be screened
for both C. trachomatis and Neisseria
gonorrhoeae. Studies indicate that up to 52% of women and 22% of
men with gonorrhea are coinfected with C. trachomatis
(2, 5). With current commercial amplification assays,
specimens must be processed and amplified separately to test for both
pathogens. A test method that can detect both pathogens by performance
of a single amplification on a processed specimen should reduce the
cost of screening.
Roche Molecular Systems has developed a multiplex PCR-based test for
C. trachomatis and N. gonorrhoeae that is
available in two formats. The fully automated COBAS AMPLICOR
CT/NG test is performed on the COBAS AMPLICOR analyzer, an
integrated unit that automatically amplifies RNA and DNA targets and
detects the resulting amplicon (20). In the semiautomated
AMPLICOR CT/NG test, amplified products are detected in an
enzyme-linked immunosorbent assay-like format on microwell plates
(22). Both CT/NG tests use a master mix containing two pairs
of primer oligonucleotides, one specific for C. trachomatis
and a second specific for N. gonorrhoeae, to simultaneously
amplify both organisms in a single processed specimen (11).
The master mix also contains an internal control (IC) DNA that monitors
amplification in each clinical specimen. The IC contains primer binding
regions identical to those of the C. trachomatis target
sequence, a randomized internal sequence similar in length and base
composition to the C. trachomatis target sequence, and a
unique probe binding region that differentiates the IC from amplified
C. trachomatis target nucleic acid (29). The
C. trachomatis, N. gonorrhoeae, and IC
amplification products are detected in separate reaction mixtures using
separate, target- and IC-specific, oligonucleotide capture probes.
In this paper, we present results of a multicenter study
evaluating the performance of the fully automated COBAS AMPLICOR CT/NG
test and the AMPLICOR CT/NG (microwell plate format) test for
C. trachomatis on endocervical swab specimens, male urethral swab specimens, and matched female and male urine specimens. The results of testing of the same specimens for N. gonorrhoeae
will be presented elsewhere.
Patient population.
In Indianapolis, Philadelphia, New
Orleans, and Galveston, specimens were collected from consecutive,
consenting individuals attending sexually transmitted disease clinics.
In Baltimore and San Francisco, specimens were collected from
consecutive, consenting individuals visiting sexually transmitted
disease clinics or family planning centers. Exclusion criteria were
insufficient volume of any specimen, mishandling or inappropriate
storage of any specimen, antibiotic therapy within 3 weeks prior to
specimen collection, urination within 2 h prior to sample
collection, and hysterectomy.
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Multicenter Evaluation of the AMPLICOR and
Automated COBAS AMPLICOR CT/NG Tests for Detection of
Chlamydia trachomatis
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
Specimen collection and storage.
Two endocervical swab
specimens from each woman and two urethral swab specimens from each man
were collected by standard procedures. The first swab was used for
gonococcal culture. The second swab was inoculated into SPG, 2SP, or
M-4 (Microtest, Inc., Snellville, Ga.) chlamydial transport medium for
chlamydial cell culture and PCR testing. These specimens were stored at
2 to 8°C and were transported to the laboratory within 24 h of
collection. An aliquot of each swab specimen was stored at 2 to 8°C
for up to 7 days postcollection and processed for PCR testing. Four
additional aliquots of each swab specimen were stored at 
70°C for
use in discrepant analysis.
20°C for
use in discrepant analysis.
Chlamydia cell culture processing and interpretation.
An
aliquot of each swab specimen was transferred for chlamydia culture
onto cycloheximide-treated McCoy cells (Indiana University [IU],
Johns Hopkins University [JHU], Louisiana State University [LSU],
University of California-San Francisco [UCSF], and Thomas Jefferson
University Hospital [TJUH]) or BGMK cells (University of Texas
Medical Branch at Galveston [UTMB]) in accordance with each
laboratory's standard procedure. The aliquot for culture was stored at
70°C if cultures were not initiated within 24 h of specimen
collection. Chlamydial inclusions were detected by immunofluorescence
using monoclonal antibodies specific for the major outer membrane
protein (MicroTrak; Syva Co., San Jose, Calif.) or lipopolysaccharide
(Kalestad, Chaska, Minn.).
PCR testing. Each specimen was processed and subjected to both the AMPLICOR and COBAS AMPLICOR tests exactly as described in the manufacturer's package inserts. For each processed specimen, the C. trachomatis, N. gonorrhoeae, and IC target DNAs were simultaneously amplified in a single reaction mixture that contained two primer pairs, one pair specific for C. trachomatis and one pair specific for N. gonorrhoeae. The resulting amplification products were captured separately and detected colorimetrically by hybridization to microwell plates (AMPLICOR format) (11) or to magnetic microparticles (COBAS AMPLICOR format) coated with N. gonorrhoeae-, C. trachomatis-, and IC-specific oligonucleotide probes. The COBAS AMPLICOR analyzer automatically performed all of the amplification, hybridization, and detection steps (12, 20). In the AMPLICOR format, amplification was performed with a GeneAmp PCR System 9600 thermal cycler (Perkin-Elmer, Norwalk, Conn.) and hybridization and detection were performed manually (22).
Interpretation of results. Specimens yielding C. trachomatis signals above the positive cutoff (optical density [OD] of 0.8) were interpreted as positive, regardless of the IC result. Specimens yielding C. trachomatis signals below the negative cutoff (OD of 0.2) were interpreted as negative, provided that the IC signal was above the assigned cutoff (OD of 0.2). Specimens yielding signals below the cutoff values for both C. trachomatis and IC were interpreted as inhibitory. Inhibitory specimens were retested by processing of a frozen aliquot of the original specimen. The repeat test results were classified using the above criteria. Repeatedly inhibitory specimens were excluded form the sensitivity and specificity calculations.
Specimens yielding C. trachomatis results between the negative and positive cutoffs (0.2
OD < 0.8) were
considered equivocal, regardless of the IC signal. Equivocal results
were resolved by retesting of the processed specimen in duplicate.
These specimens were interpreted as positive if at least one of the two
repeat tests yielded a C. trachomatis OD of 
0.2. These
specimens were interpreted as negative if the two repeat tests yielded
C. trachomatis signals of <0.2 OD, provided that the IC
signals were above the assigned cutoff. If the two repeat tests yielded
a C. trachomatis OD of <0.2 and the IC signal was below the
assigned cutoff for either of the duplicate repeat tests, the specimen
was interpreted as inhibitory and was excluded from sensitivity and
specificity calculations.
Resolution of discordant results. Specimens that were positive by PCR but negative by culture were resolved by direct fluorescent-antibody (DFA) (MicroTrak) testing on the transport medium sediment obtained following centrifugation. If the DFA test was negative, the specimen was tested with a PCR assay for an alternative target DNA sequence, a portion of the major outer membrane protein (MOMP) gene (13). If the specimen was negative in the MOMP test, the other specimen type was also tested for MOMP to provide evidence that the patient was infected; this test was performed regardless of whether the second specimen type had originally tested positive for C. trachomatis.
Calculation of test performance. Sensitivity and specificity were calculated in two ways. Calculations on a patient basis used the culture results, the results of all four PCR tests (swab and urine specimens, each tested by AMPLICOR and COBAS AMPLICOR), and results of DFA and MOMP testing, when necessary, to ascertain infected patients. A patient was considered infected if the culture was positive or if any one of the four PCR tests was positive and either the swab was positive by DFA testing or the swab or urine specimen was positive by the MOMP test. The second calculation evaluated results on a sample basis to show the performance that would have been obtained if only one specimen type had been tested in one assay format. For each specimen type tested in each format, infected patients were ascertained using culture and only the PCR result for the specimen type and test format under consideration; patients who were PCR positive only for a different specimen or format were considered uninfected in this analysis. A patient was considered infected if (i) the culture was positive or (ii) the PCR test under consideration was positive and either the swab specimen was positive by DFA or any specimen was positive in the MOMP test.
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RESULTS |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Patient population. Totals of 1,134 asymptomatic women, 1,173 symptomatic women, 723 asymptomatic men, and 1,298 symptomatic men were enrolled in the study. Of these, seven asymptomatic women, four symptomatic women, and two symptomatic men were excluded because culture results were not available. For another 29 asymptomatic women, 31 symptomatic women, 13 asymptomatic men, and 66 symptomatic men (total = 139), results were missing for at least one specimen type in at least one test format, either because a test was not performed (n = 31) or because a specimen was repeatedly inhibitory (n = 108) in either the COBAS AMPLICOR or the AMPLICOR test. Thus, there were valid results for 1,098 asymptomatic women, 1,138 symptomatic women, 710 asymptomatic men, and 1,230 symptomatic men for both specimen types (swab and urine) and both test formats (COBAS AMPLICOR and AMPLICOR), for a total of four valid PCR results.
Initially, we evaluated test performance for all subjects whose culture results were valid. We then performed the same analyses for the subset of subjects for whom four PCR results were valid. The two analyses yielded virtually identical results for prevalence, sensitivity, specificity, and concordance between the COBAS AMPLICOR and AMPLICOR formats. In this paper, we present the data for the subset of subjects for whom four PCR results were valid.Concordance between test formats.
Matched swab and urine
specimens obtained from 4,176 patients yielded valid test results in
both the COBAS AMPLICOR and AMPLICOR formats, for a total of 8,352 test
results in each test format. The AMPLICOR and COBAS AMPLICOR
results were 98.1% concordant (98.4 and 97.8% for swab and
urine specimens, respectively; Table 1).
The number of COBAS AMPLICOR-positive, AMPLICOR-negative specimens was
virtually identical to the number of COBAS AMPLICOR-negative, AMPLICOR-positive specimens. Consistent with this high degree of
concordance, the two test formats exhibited virtually identical performance characteristics (data not shown). Thus, for simplicity of
presentation, the remainder of this paper will focus on results obtained with the COBAS AMPLICOR test format. Nevertheless, results obtained with the AMPLICOR microwell plate format were used to identify
infected patients.
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Frequency of inhibition.
Overall, 203 (2.4%) of 8,618 specimens inhibited amplification of the IC in the COBAS AMPLICOR
test (Table 2). Endocervical swab,
asymptomatic male urethral swab, and asymptomatic male urine specimens
exhibited the lowest inhibition rates (1%; Table 2). Symptomatic
male urethral swabs had a slightly higher inhibition rate (2%), and
female urine and symptomatic male urine specimens had the highest
inhibition rates (3 to 5%).
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Results for C. trachomatis in women.
Test
performance was calculated from the 1,098 asymptomatic and 1,138 symptomatic women whose results were valid for both specimen types in
both test formats. C. trachomatis infection was detected in
95 (8.7%) of the asymptomatic women, 69 of whom were positive by
culture, and 108 (9.5%) of the symptomatic women, 86 of whom were
positive by culture (Table 3). For the 26 asymptomatic and 22 symptomatic, culture-negative, infected
women, at least one specimen type gave a positive result in at
least one PCR test format; the PCR results were confirmed by DFA
testing or by PCR testing for an alternative target sequence within the
C. trachomatis MOMP gene (Table 3). C. trachomatis was detected only in the swab specimen (i.e., the
urine specimen was negative in both PCR tests) for 11 of the 95 asymptomatic and 5 of the 108 symptomatic, infected women. C. trachomatis was detected only in the urine specimen (i.e., the
swab specimen was negative by culture and both PCR tests) for a similar
number of women: nine asymptomatic and four symptomatic, infected
women.
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(i) Endocervical swabs. COBAS AMPLICOR performed on endocervical swab specimens yielded positive results for 97.1% (67 of 69) of asymptomatic and 95.3% (82 of 86) of symptomatic, culture-positive women (Table 3). COBAS AMPLICOR performed on endocervical swab specimens also yielded positive results for 61.5% (16 of 26) of asymptomatic and 77.3% (17 of 22) of symptomatic, infected, culture-negative women (Table 3).
The sensitivity, specificity, and positive and negative predictive values were calculated from these results (Table 4). COBAS AMPLICOR performance on endocervical swab specimens was slightly more sensitive for symptomatic women (91.7%) than for asymptomatic women (87.4%). COBAS AMPLICOR performed on endocervical swab specimens exhibited virtually identical specificities (99.5 versus 99.2%) for both asymptomatic and symptomatic women. The PCR test performed similarly in all six laboratories (data not shown), while there was considerable variation in culture sensitivity (see Table 6) among laboratories.
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(ii) Female urine specimens. COBAS AMPLICOR performed on urine specimens yielded positive results for 91.3% (63 of 69) of asymptomatic and 91.9% (79 of 86) of symptomatic, culture-positive women (Table 3). PCR performed on urine specimens also yielded positive results for 76.9% (20 of 26) of asymptomatic and 86.4% (19 of 22) of symptomatic, infected, culture-negative women (Table 3).
The sensitivity, specificity, and positive and negative predictive values were calculated from these results (Table 4). COBAS AMPLICOR performed on urine specimens was slightly more sensitive for symptomatic women (90.7%) than for asymptomatic women (87.4%). COBAS AMPLICOR performed on urine specimens exhibited similar specificities (99.6 versus 98.4%) for both asymptomatic and symptomatic women. The test performed similarly in all six laboratories (data not shown). Two of the 70 initially inhibitory urine samples were obtained from asymptomatic, infected (1 culture positive, PCR positive and 1 culture negative, PCR positive) women. These specimens were inhibitory when retested and were thus excluded from performance calculations. If the IC had not been used, these specimens would have been scored as false negative. Use of the IC had no impact on sensitivity for urine from symptomatic women.Results for C. trachomatis in men. Test performance was calculated from the 710 asymptomatic and 1,230 symptomatic men whose results were valid for both specimen types in both test formats. C. trachomatis infection was detected in 89 (12.5%) of the asymptomatic men, 73 of whom were positive by culture, and 261 (21.2%) of the symptomatic men, 169 of whom were positive by culture (Table 3). In the remaining 16 asymptomatic and 92 symptomatic, infected men, at least one specimen type gave a positive result in at least one PCR test format; the PCR results were confirmed by DFA testing or by PCR testing for an alternative target sequence within the C. trachomatis MOMP gene (Table 3). C. trachomatis was detected only in the swab specimens of 6 of the 89 asymptomatic and 19 of the 261 symptomatic, infected men. C. trachomatis was detected only in the urine specimens of similar numbers of men: 6 asymptomatic and 25 symptomatic, infected men.
Both specimen types gave negative COBAS AMPLICOR results for 605 of the 621 asymptomatic and 943 of the 969 symptomatic, uninfected men (Table 3). At least one specimen type gave a positive COBAS AMPLICOR result for the remaining 16 asymptomatic and 26 symptomatic, uninfected men; these positive results represent false positives, since none were confirmed by DFA or MOMP PCR testing (Table 3).(i) Urethral swabs. COBAS AMPLICOR performed on urethral swab specimens yielded positive results for 98.6% (72 of 73) of asymptomatic and 96.4% (163 of 169) of symptomatic, culture-positive men (Table 3). COBAS AMPLICOR performed on urethral swab specimens also yielded positive results for 62.5% (10 of 16) of asymptomatic and 70.7% (65 of 92) of symptomatic, infected, culture-negative men (Table 3).
The sensitivity, specificity, and positive and negative predictive values were calculated from these results (Table 4). COBAS AMPLICOR performed on urethral swab specimens was slightly more sensitive for asymptomatic men (92.1%) than for symptomatic men (87.4%). COBAS AMPLICOR performed on urethral swab specimens exhibited the same specificity (98.7%) for both asymptomatic and symptomatic men. The test performed similarly in the five laboratories that tested male specimens (data not shown). One of the 30 initially inhibitory urethral swab specimens (6 asymptomatic and 24 symptomatic; Table 2) was obtained from a symptomatic, infected (culture-negative, urine PCR-positive) man. This specimen was inhibitory when retested and was thus excluded from performance calculations. If the IC had not been used, this specimen would have been scored as false negative. Use of the IC had no impact on sensitivity for urethral swab specimens from asymptomatic men.(ii) Urine specimens. COBAS AMPLICOR performed on urine specimens yielded positive results for 90.4% (66 of 73) of asymptomatic and 88.8% (150 of 169) of symptomatic, culture-positive men (Table 3). COBAS AMPLICOR performed on urine specimens also yielded positive results for 100.0% (16 of 16) of asymptomatic and 91.3% (84 of 92) of symptomatic, infected, culture-negative men (Table 3).
The sensitivity, specificity, and positive and negative predictive values were calculated from these results (Table 4). COBAS AMPLICOR performed on urine specimens was slightly more sensitive for asymptomatic men (92.1%) than for symptomatic men (89.7%). COBAS AMPLICOR performed on urine specimens exhibited virtually identical specificities (98.4 versus 98.5%) for both asymptomatic and symptomatic men. The test performed similarly in four of the five laboratories (data not shown). The sensitivity of COBAS AMPLICOR performed on urine specimens tested at one site, however, was significantly lower than that observed at the other four sites. The combined sensitivity for asymptomatic and symptomatic males at this site was 74.4% (67 of 90), compared to 95.8% (249 of 260) for the other four sites. Thirteen of the 72 initially inhibitory urine specimens (2 asymptomatic and 70 symptomatic; Table 2) were obtained from symptomatic, infected (seven culture-positive, urethral PCR-positive and six culture-negative, urethral PCR-positive) men. One initially inhibitory, culture-positive specimen was negative when retested and was scored as false negative, regardless of whether the IC was used. Five (1 culture positive and 4 culture-negative, urethral PCR positive) of the 13 initially inhibitory specimens were inhibitory when retested and were thus excluded from performance calculations. Seven (five culture positive and two culture negative, urethral PCR positive) of the initially inhibitory specimens that yielded positive results when retested were interpreted as true positive when the IC was used but would have been interpreted as false negative if the IC had not been used. Thus, 12 additional specimens would have been scored as false negative without the IC, thereby lowering sensitivity for urine from symptomatic men from 89.7% (234 of 261) to 85.3% (227 of 266). Use of the IC had no impact on sensitivity for urine specimens from asymptomatic men.Individual specimen performance calculations.
Certain
infected, culture-negative patients yielded negative COBAS AMPLICOR
results for one specimen type; they were identified as positive because
the other specimen type was COBAS AMPLICOR positive or because at least
one specimen type was positive in the AMPLICOR format. If only one test
had been performed, only those COBAS AMPLICOR-negative specimens
obtained from culture-positive patients would have been interpreted as
false negative. Consequently, the resulting sensitivities would have
ranged from 92.1 to 98.8% if only one specimen type had been tested in
the COBAS AMPLICOR format only (Table 5).
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Detection of C. trachomatis in specimens coinfected with N. gonorrhoeae. A total of 3.7% (159 of 4,315) of the individuals tested were coinfected. The rates of C. trachomatis coinfection among N. gonorrhoeae-infected individuals were 27.6% (16 of 58) and 36.3% (33 of 91), respectively, for asymptomatic and symptomatic women and 18.5% (5 of 27) and 27.1% (105 of 388), respectively, for asymptomatic and symptomatic men.
COBAS AMPLICOR detected C. trachomatis in 82.9% (131 of 158; 1 specimen was inhibitory) of the swab specimens tested and 87.6% (134 of 153; 6 specimens were inhibitory) of the urine specimens tested from individuals coinfected with N. gonorrhoeae. The sensitivity for C. trachomatis in coinfected individuals was similar to that observed in all individuals, with the exception of urethral swab specimens obtained from symptomatic men, where the sensitivity was 76.9% (80 of 104) for coinfected men, compared to 87.4% (228 of 261) for all of the men.Prevalence of infection in different populations.
The overall
prevalence of infection varied between sites, ranging from 2.5 to
23.1% in asymptomatic women and from 4.9 to 16.2% in symptomatic
women (Table 6). The prevalence of
infection was lower in asymptomatic women than in symptomatic women at
three sites but higher at the other three sites. Similarly, the
prevalence of infection ranged from 6.6 to 20.1% in asymptomatic men
and from 18.5 to 37.9% in symptomatic men (Table 6). At all five sites, the prevalence was lower in asymptomatic men than in symptomatic men. The combination of five tests
culture, COBAS AMPLICOR and AMPLICOR performed on swab specimens, and COBAS AMPLICOR and AMPLICOR performed on urine specimensyielded overall prevalences that were
38.1, 25.0, 21.4, and 54.7% higher than the prevalences determined by
culture for asymptomatic women, symptomatic women, asymptomatic men,
and symptomatic men, respectively.
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DISCUSSION |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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The results of this study demonstrate that the COBAS AMPLICOR and AMPLICOR CT/NG (data not shown) tests exhibit excellent sensitivity and specificity for C. trachomatis. In both men and women, the COBAS AMPLICOR test exhibited essentially the same sensitivity for urine and urogenital swab specimens. Sensitivity was somewhat higher in symptomatic than in asymptomatic women and in asymptomatic than in symptomatic men. When COBAS AMPLICOR test results were compared to patients defined as infected, the test sensitivities for the individual specimen types ranged from 87.4 to 92.1%. In contrast, the sensitivity of culture was only 64.8 to 82.0%. Thus, PCR performed on any one specimen type detected approximately 10 to 20% more infections than cell culture. The specificity of the COBAS AMPLICOR test ranged from 98.4 to 99.6%, and the positive and negative predictive values ranged from 86.0 to 95.4% and from 96.7 to 99.1%, respectively. Similar results were obtained with the COBAS AMPLICOR test in two other studies in which both swab and urine specimens were tested and PCR results were compared to the infected patient standard (14, 35).
Somewhat higher sensitivities (92 to 94%) were reported in two studies in which urine specimens only were tested by COBAS AMPLICOR (27, 32). Other recent studies have also demonstrated that the estimate of sensitivity for each specimen type is lower when multiple specimens from each patient are tested and the infected patient is used as the "gold standard" (8, 14). Testing of multiple specimens detects a greater number of infections but, predictably, has lower sensitivity compared to single-specimen testing, because some patients yield positive results for only one specimen type. This reduction in sensitivity may introduce a bias into the analysis of test performance, but that bias equally affects all of the tests considered, including culture sensitivity. In the present study, depending on the patient group, 4.3 to 11.6% of infected patients yielded positive results for urogenital swab specimens only and 3.7 to 9.5% of infected subjects yielded positive results for urine specimens only.
To compare the performance achieved in this study to that obtained in earlier studies, we also calculated performance as if only one specimen from each patient had been tested. Test sensitivity ranged from 92.1 to 98.8%, and specificity ranged from 98.4 to 99.6%. Thus, the results of the multiplex COBAS AMPLICOR and AMPLICOR CT/NG (data not shown) tests match those obtained with other semiautomated amplification-based tests that detect only C. trachomatis (7, 14, 21), including the AMPLICOR C. trachomatis test (3, 7, 28, 36).
The multiplex COBAS AMPLICOR test was able to amplify and detect C. trachomatis DNA in the presence of N. gonorrhoeae DNA. Overall, 27.0% of C. trachomatis-infected patients were coinfected with N. gonorrhoeae. The sensitivity of COBAS AMPLICOR for C. trachomatis was similar whether or not coinfection was present for all specimen types, except urethral swab specimens from symptomatic men, in which case the sensitivity was lower for coinfected specimens. For this reason, urine is the preferred specimen type for testing of symptomatic men.
Each study site adhered to its standard protocol for the collection, transportation, and inoculation of tissue culture. Variations in technique, such as the use of shell vials versus microtiter plates, were not controlled for, since they reflected the protocol of each laboratory. Therefore, the results reported here are representative of the results routinely available from these laboratories. The sensitivity of culture exhibited considerable variation between clinical test sites. Most likely, this reflects a combination of differences in skill between the clinicians collecting the specimens, differences in the transport and storage conditions, and variability in laboratory expertise. In contrast, the sensitivity of PCR varied little between sites. This suggests that the sensitivity of PCR is much less dependent on specimen collection, transport, and laboratory technique, which represents another advantage of PCR over culture.
The COBAS AMPLICOR and AMPLICOR tests include an IC to ensure the integrity of negative results and maximize test sensitivity by monitoring amplification in specimens yielding negative test results. In the COBAS AMPLICOR test format, the cost of using the IC can be minimized by programming the analyzer to detect the IC only in those specimens that test negative for C. trachomatis. Use of the IC increased test sensitivity by 1.8, 0.4, and 4.3% for asymptomatic female urine, symptomatic male urethral swab, and symptomatic male urine specimens, respectively. The IC enabled us to definitively determine that the frequency of inhibition in this study ranged from <1% in endocervical specimens to 5% in urine specimens from symptomatic males. Similar inhibition rates have recently been reported (23, 33). It is difficult to directly compare the frequencies of inhibition for different amplification technologies because the commercially available ligase chain reaction (LCx) and transcription-mediated amplification (TMA) C. trachomatis tests lack an IC, making it impossible to assess inhibition in reference test-negative specimens. One study overcame this problem by comparing inhibition in specimens that had been seeded with a small, defined quantity of C. trachomatis DNA (23). This study showed that the AMPLICOR CT/NG and LCx C. trachomatis tests had similar inhibition rates but that the inhibition rate for the TMA test was 2.5-fold higher (23). In published clinical evaluations, the frequency of inhibitory, positive specimens can be estimated from the frequency of reference test-positive, amplification test-negative specimens that give positive results when retested (29). This type of analysis suggests that the inhibition rates in positive specimens are 1 to 30% for the LCx C. trachomatis test (1, 4, 8-10, 19, 26, 34) and approximately 8% for the TMA C. trachomatis test (25). The inhibition rate for all specimens is probably higher, since weak inhibition may go undetected in positive specimens that contain relatively high target concentrations (29). Indeed, the IC results in this study demonstrated that the inhibition frequency (i.e., the proportion of specimens giving negative results for both C. trachomatis and the IC) was higher for culture-negative specimens (2.5%; 195 of 7,732) than for culture-positive specimens (0.9%; 8 of 886).
The combined performance of two PCR tests on two specimens from each patient detected 98.0% (389 of 397) of the culture-positive individuals. This high detection rate, coupled with the use of the IC to eliminate false-negative results due to inhibition, makes it likely that we detected the vast majority of culture-negative infections, thus minimizing any bias that might be introduced as a result of discrepant analysis (16). The use of discrepant analysis is further justified because any bias it introduces is less than the bias that results from comparing a test to a less sensitive gold standard without resolving discrepancies (15). In addition, the existence of infections that were missed by both PCR and culture would not change the conclusion that PCR performed on a single specimen type detects 10 to 20% more infections than culture because the sensitivity of both methods would be reduced proportionately.
In summary, both the COBAS AMPLICOR and AMPLICOR CT/NG tests exhibited equally high sensitivities and specificities for C. trachomatis with both urogenital swab and urine specimens and are thus well suited for screening for C. trachomatis in male and female urine specimens. Elsewhere, we will demonstrate that these tests can be used to simultaneously screen for N. gonorrhoeae infections (D. H. Martin et al., unpublished data). Thus, the COBAS AMPLICOR and AMPLICOR tests make it possible to screen for both pathogens by processing and amplifying a specimen once.
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ACKNOWLEDGMENTS |
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We thank Maurice Rosenstraus for manuscript review, James F. Kelly for database management, James Williams and Laura Brandenburg for laboratory assistance, and the many clinicians at each site for assistance with enrolling patients.
This work was supported by Roche Molecular Systems.
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FOOTNOTES |
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* Corresponding author. Mailing address: 545 N. Barnhill #435, Indianapolis, IN 46202. Phone: (317) 274-1422. Fax: (317) 278-1114. E-mail: bvanderp{at}iupui.edu.
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REFERENCES |
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Abstract
Introduction
Materials and Methods
Results
Discussion
References
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| 1. | Bassiri, M., H. Y. Hu, M. A. Domeika, J. Burczak, L. O. Svensson, H. H. Lee, and P. A. Mardh. 1995. Detection of Chlamydia trachomatis in urine specimens from women by ligase chain reaction. J. Clin. Microbiol. 33:898-900[Abstract]. |
| 2. | Batteiger, B. E., J. Fraiz, W. J. Newhall, B. P. Katz, and R. B. Jones. 1989. Association of recurrent chlamydial infection with gonorrhea. J. Infect. Dis. 159:661-669[Medline]. |
| 3. |
Bauwens, J. E.,
A. M. Clark,
M. J. Loeffelholz,
S. A. Herman, and W. E. Stamm.
1993.
Diagnosis of Chlamydia trachomatis urethritis in men by polymerase chain reaction assay of first-catch urine.
J. Clin. Microbiol.
31:3013-3016 |
| 4. | Berg, E. S., G. Anestad, H. Moi, G. Storvorld, and K. Skaug. 1997. False-negative results of a ligase chain reaction assay to detect Chlamydia trachomatis due to inhibitors in urine. Eur. J. Clin. Microbiol. Infect. Dis. 16:727-731[CrossRef][Medline]. |
| 5. | Burstein, G. R., G. Waterfield, A. Joffe, J. M. Zenilman, T. C. Quinn, and C. A. Gaydos. 1998. Screening for gonorrhea and chlamydia by DNA amplification in adolescents attending middle school health centers. Sex. Transm. Dis. 25:395-402[Medline]. |
| 6. |
Centers for Disease Control.
1997.
Chlamydia trachomatis genital infectionsUnited States, 1995.
Morbid. Mortal. Weekly Rep.
46:193-198[Medline].
|
| 7. | Chernesky, M. A., S. Chong, D. Jang, K. Luinstra, J. Sellors, and J. B. Mahony. 1997. Ability of commercial ligase chain reaction and PCR assays to diagnose Chlamydia trachomatis infections in men by testing first-void urine. J. Clin. Microbiol. 35:982-984[Abstract]. |
| 8. | Chernesky, M. A., D. Jang, J. Sellors, K. Luinstra, S. Chong, S. Castriciano, and J. B. Mahony. 1997. Urinary inhibitors of polymerase chain reaction and ligase chain reaction and testing of multiple specimens may contribute to lower assay sensitivities for diagnosing Chlamydia trachomatis infected women. Mol. Cell. Probes 11:243-249[CrossRef][Medline]. |
| 9. | Chernesky, M. A., H. Lee, J. Schachter, J. D. Burczak, W. E. Stamm, W. M. McCormack, and T. C. Quinn. 1994. Diagnosis of Chlamydia trachomatis urethral infection in symptomatic and asymptomatic men by testing first-void urine in a ligase chain reaction assay. J. Infect. Dis. 170:1308-1311[Medline]. |
| 10. | Ching, S., H. Lee, E. W. Hook III, M. R. Jacobs, and J. Zenilman. 1995. Ligase chain reaction for detection of Neisseria gonorrhoeae in urogenital swabs. J. Clin. Microbiol. 33:3111-3114[Abstract]. |
| 11. | Crotchfelt, K. A., L. E. Welsh, D. DeBonville, M. Rosenstraus, and T. C. Quinn. 1997. Detection of Neisseria gonorrhoeae and Chlamydia trachomatis in genitourinary specimens from men and women by a coamplification PCR assay. J. Clin. Microbiol. 35:1536-1540[Abstract]. |
| 12. |
DiDomenico, N.,
H. Link,
R. Knobel,
T. Caratsch,
W. Weschler,
Z. G. Loewy, and M. Rosenstraus.
1996.
COBAS AMPLICORTM: a fully automated RNA and DNA amplification and detection system for routine diagnostic PCR.
Clin. Chem.
42:1915-1923 |
| 13. | Dutilh, B., C. Bebear, P. Rodriguez, A. Vekris, J. Bonnet, and M. Garret. 1989. Specific amplification of a DNA sequence common to all Chlamydia trachomatis serovars using the polymerase chain reaction. Res. Microbiol. 140:7-16[Medline]. |
| 14. | Goessens, W. H. F., J. W. Mouton, W. I. van der Meijden, S. Deelen, T. H. van Rijsoort-Vos, N. Lemmens-den Toom, H. A. Verbrugh, and R. Verkooyen. 1997. Comparison of three commercially available amplification assays, AMP CT, LCx, and COBAS AMPLICOR, for detection of Chlamydia trachomatis in first-void urine. J. Clin. Microbiol. 35:2628-2633[Abstract]. |
| 15. |
Green, T. A.,
C. M. Black, and R. E. Johnson.
1998.
Evaluation of bias in diagnostic-test sensitivity and specificity estimates computed by discrepant analysis.
J. Clin. Microbiol.
36:375-381 |
| 16. | Hagdu, A. 1996. The discrepancy in discrepant analysis. Lancet 348:592-593[CrossRef][Medline]. |
| 17. | Hook, E. W., III, K. Smith, C. Mullen, J. Stephens, L. Rinehardt, M. S. Pate, and H. Lee. 1997. Diagnosis of genitourinary Chlamydia trachomatis infections by using the ligase chain reaction on patient-obtained vaginal swabs. J. Clin. Microbiol. 35:2133-2135[Abstract]. |
| 18. | Howell, M. R., T. C. Quinn, W. Brathwaite, and C. A. Gaydos. 1998. Screening women for Chlamydia trachomatis in family planning clinics: the cost-effectiveness of DNA amplification assays. Sex. Transm. Dis. 25:108-117[Medline]. |
| 19. | Jensen, I. P., P. Thorsen, and B. R. Moller. 1997. Sensitivity of ligase chain reaction assay of urine from pregnant women for Chlamydia trachomatis. Lancet 349:329-330[Medline]. |
| 20. | Jungkind, D., S. DiRenzo, K. G. Beavis, and N. S. Silverman. 1996. Evaluation of automated COBAS AMPLICOR PCR system for detection of several infectious agents and its impact on laboratory management. J. Clin. Microbiol. 34:2778-2783[Abstract]. |
| 21. | Lee, H. H., M. A. Chernesky, J. Schachter, J. D. Burczak, W. W. Andrews, S. Muldoon, G. Leckie, and W. E. Stamm. 1995. Diagnosis of Chlamydia trachomatis genitourinary infection in women by ligase chain reaction assay of urine. Lancet 345:213-216[CrossRef][Medline]. |
| 22. |
Loeffelholz, M. J.,
C. A. Lewinski,
S. R. Silver,
A. P. Purohit,
S. A. Herman,
D. A. Buonagurio, and E. A. Dragon.
1992.
Detection of Chlamydia trachomatis in endocervical specimens by polymerase chain reaction.
J. Clin. Microbiol.
30:2847-2851 |
| 23. |
Mahony, J.,
S. Chong,
D. Jang,
K. Luinstra,
M. Faught,
D. Dalby,
J. Sellors, and M. Chernesky.
1998.
Urine specimens from pregnant and nonpregnant women inhibitory to amplification of Chlamydia trachomatis nucleic acid by PCR, ligase chain reaction, and transcription-mediated amplification: identification of urinary substances associated with inhibition and removal of inhibitory activity.
J. Clin. Microbiol.
36:3122-3126 |
| 24. |
Mertz, K. J.,
W. C. Levine,
D. J. Mosure,
S. M. Berman, and K. J. Dorian.
1997.
Trends in the prevalence of chlamydial infectionsthe impact of community wide testing.
Sex. Transm. Dis.
24:169-175[Medline].
|
| 25. | Pasternack, R., P. Vourinen, and A. Miettinen. 1997. Evaluation of the Gen-Probe Chlamydia trachomatis transcription-mediated amplification assay with urine specimens from women. J. Clin. Microbiol. 35:676-678[Abstract]. |
| 26. | Pasternack, R., P. Vourinen, T. Pitkajarvi, M. Koskela, and A. Miettinen. 1997. Comparison of manual AMPLICOR PCR, COBAS AMPLICOR PCR, and LCx assays for detection of Chlamydia trachomatis infection in women by using urine specimens. J. Clin. Microbiol. 35:402-405[Abstract]. |
| 27. | Puolakkainen, M., E. Hiltunen-Back, T. Reunala, S. Suhonen, P. Lähteenmäki, M. Lehtinen, and J. Paavonen. 1997. Comparison of performance of two commercially available tests, a PCR assay and a ligase chain reaction test, in detection of urogenital Chlamydia trachomatis infection. J. Clin. Microbiol. 35:2628-2633. |
| 28. | Quinn, T. C., L. Welsh, A. Lentz, K. Crotchfelt, J. Zenilman, J. Newhall, and C. Gaydos. 1996. Diagnosis by AMPLICOR PCR of Chlamydia trachomatis infection in urine samples from women and men attending sexually transmitted disease clinics. J. Clin. Microbiol. 34:1401-1406[Abstract]. |
| 29. |
Rosenstraus, M.,
Z. Wang,
S. Y. Chang,
D. DeBonville, and J. P. Spadoro.
1998.
An internal control for routine diagnostic PCR: design, properties and effect on clinical performance.
J. Clin. Microbiol.
36:191-197 |
| 30. |
Scholes, D.,
A. Stergachis,
F. E. Heidrich,
H. Andrilla,
K. K. Holmes, and W. Stamm.
1997.
Prevention of pelvic inflammatory disease by screening for cervical chlamydial infection.
N. Engl. J. Med.
334:1362-1366 |
| 31. | Stary, A., B. Najim, and H. H. Lee. 1997. Vulval swabs as alternative specimens for ligase chain reaction detection of genital chlamydial infection in women. J. Clin. Microbiol. 35:836-838[Abstract]. |
| 32. | Steingrímsson, O., K. Jonsdottir, J. H. Olafsson, S. M. Karlsson, R. Palsdottir, and S. Davidsson. 1998. Comparison of Roche COBAS AMPLICOR and Abbott LCx for the rapid detection of Chlamydia trachomatis in specimens from high risk patients. Sex. Transm. Dis. 25:44-48[Medline]. |
| 33. |
Toye, B.,
W. Woods,
M. Bobrowska, and K. Ramotar.
1998.
Inhibition of PCR in genital and urine specimens submitted for Chlamydia trachomatis testing.
J. Clin. Microbiol.
36:2356-2358 |
| 34. | van Doornum, G. J. J., M. Buimer, M. Prins, C. J. M. Henquet, R. A. Coutinho, P. K. Plier, S. Tomazic-Allen, H. Hu, and H. Lee. 1995. Detection of Chlamydia trachomatis infection in urine samples from men and women by ligase chain reaction. J. Clin. Microbiol. 33:2042-2047[Abstract]. |
| 35. |
Vincelette, J.,
J. Schirm,
M. Bogard,
A.-M. Bourgault,
D. S. Luijt,
A. Bianchi,
P. C. van Voorst Vader,
A. Butcher, and M. Rosenstraus.
1999.
Multicenter evaluation of the fully automated COBAS AMPLICOR PCR test for detection of Chlamydia trachomatis in urogenital specimens.
J. Clin. Microbiol.
37:74-80 |
| 36. | Wiesenfeld, H. C., M. Uhrin, B. W. Dixon, and R. L. Sweet. 1994. Diagnosis of male Chlamydia trachomatis urethritis by polymerase chain reaction. Sex. Transm. Dis. 21:268-271[Medline]. st |
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[Abstract] [Full Text] -
Mahony, J. B., Song, X., Chong, S., Faught, M., Salonga, T., Kapala, J.
(2001). Evaluation of the NucliSens Basic Kit for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in Genital Tract Specimens Using Nucleic Acid Sequence-Based Amplification of 16S rRNA. J. Clin. Microbiol.
39: 1429-1435
[Abstract] [Full Text] -
Morency, P, Dubois, M J, Gresenguet, G, Frost, E, Masse, B, Deslandes, S, Somse, P, Samory, A, Mberyo-Yaah, F, Pepin, J
(2001). Aetiology of urethral discharge in Bangui, Central African Republic. Sex. Transm. Infect.
77: 125-129
[Abstract] [Full Text] -
van Doornum, G. J. J., Schouls, L. M., Pijl, A., Cairo, I., Buimer, M., Bruisten, S.
(2001). Comparison between the LCx Probe System and the COBAS AMPLICOR System for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae Infections in Patients Attending a Clinic for Treatment of Sexually Transmitted Diseases in Amsterdam, The Netherlands. J. Clin. Microbiol.
39: 829-835
[Abstract] [Full Text] -
Van Der Pol, B., Ferrero, D. V., Buck-Barrington, L., Hook, E. III, Lenderman, C., Quinn, T., Gaydos, C. A., Lovchik, J., Schachter, J., Moncada, J., Hall, G., Tuohy, M. J., Jones, R. B.
(2001). Multicenter Evaluation of the BDProbeTec ET System for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in Urine Specimens, Female Endocervical Swabs, and Male Urethral Swabs. J. Clin. Microbiol.
39: 1008-1016
[Abstract] [Full Text] -
Johnson, R. E., Green, T. A., Schachter, J., Jones, R. B., Hook, E. W. III, Black, C. M., Martin, D. H., St. Louis, M. E., Stamm, W. E.
(2000). Evaluation of Nucleic Acid Amplification Tests as Reference Tests for Chlamydia trachomatis Infections in Asymptomatic Men. J. Clin. Microbiol.
38: 4382-4386
[Abstract] [Full Text] -
Hadgu, A., McAdam, A. J.
(2000). Discrepant Analysis Is an Inappropriate and Unscientific Method. J. Clin. Microbiol.
38: 4301-4302
[Full Text] -
Martin, D. H., Cammarata, C., Van Der Pol, B., Jones, R. B., Quinn, T. C., Gaydos, C. A., Crotchfelt, K., Schachter, J., Moncada, J., Jungkind, D., Turner, B., Peyton, C.
(2000). Multicenter Evaluation of AMPLICOR and Automated COBAS AMPLICOR CT/NG Tests for Neisseria gonorrhoeae. J. Clin. Microbiol.
38: 3544-3549
[Abstract] [Full Text]
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