Assessment of best single sample for finding chlamydia in women with and without symptoms: a diagnostic test study

Abstract

Objective To compare vulvovaginal swabs with endocervical swabs as optimal diagnostic sample for detection of Chlamydia trachomatis infection.Design A diagnostic test study.Setting An urban sexual health centre.Participants 3973 women aged ≥16 years requesting testing for sexually transmitted infections.Interventions Participants took a vulvovaginal swab before routine examination, and clinicians took an endocervical swab during examination.Main outcome measure Diagnosis of chlamydia infection with samples analysed using the Aptima Combo-2 assay; positive results confirmed with the Aptima CT assay. ResultsOf the 3973 participants, 410 (10.3%) were infected with C trachomatis. Infected women were significantly younger (22 v 25 years, P<0.0001) and more likely to have symptoms suggestive of a bacterial sexually transmitted infection (53% v 41%, odds ratio 1.63 (95% CI 1.30 to 2.04)), be a contact of someone with a sexually transmitted infection (25% v 5%, odds ratio 6.18 (4.61 to 8.30)), clinically diagnosed with cervicitis (17% v 4%, odds ratio 4.92 (3.50 to 6.91)), and have pelvic inflammatory disease (9% v 3%, odds ratio 2.85 (1.87 to 4.33)). When women co-infected with gonorrhoea were included in the analysis, there was an association with mixed ethnicity (10% v 7%, odds ratio 1.53 (1.07 to 2.17)); but when those with gonorrhoea were removed, women of white ethnicity were significantly more likely to have chlamydia (85% v 80%, odds ratio 1.40 (1.03 to 1.91)). On analysis of complete paired results, vulvovaginal swabs were significantly more sensitive than endocervical swabs (97% (95% CI 95% to 98%) v 88% (85% to 91%), P<0.00001); corresponding specificities were 99.9% and 100%. In women with symptoms suggestive of a bacterial sexually transmitted infection, vulvovaginal swabs were significantly more sensitive than endocervical swabs (97% (93% to 98%) v 88% (83% to 92%), P=0.0008), as they were in women without symptoms (97% (94% to 99%) v 89% (84% to 93%), P=0.002). ConclusionsVulvovaginal swabs are significantly better than endocervical swabs at detecting chlamydia in women with and without symptoms suggestive of sexually transmitted infections. In those with symptoms, using endocervical samples rather than vulvovaginal swabs would have missed 9% of infections, or 1 in every 11 cases of chlamydia. Trial registration ISRCTN42867448. IntroductionChlamydia is the most common sexually transmitted infection diagnosed and treated in the United Kingdom, 1 with the highest rates in young people under the age of 25 years. It is often asymptomatic but can have serious sequelae if left untreated. In women, ascending infection causes pelvic inflammatory disease with potential complications of infertility and ectopic pregnancy. Chlamydia trachomatis can infect the urethra or endocervix, or both. Studies looking at sites of chlamydia infection in women found chlamydia present in both urethra and endocervix in 73-76%, endocervix only in 15-16%, and urethra only in 10-11%.2 3 The optimal diagnostic sample must be abl...

A cross-sectional study showing differences in the clinical diagnosis of pelvic inflammatory disease according to the experience of clinicians: implications for training and audit

“…Data were obtained from records of a CT and NG diagnostic test accuracy study conducted at Leeds Centre for Sexual Health (LCSH) between March 2009 and January 2010, in which this study was nested. The full methods are described elsewhere 13 14. The range of clinicians involved included Band 5 nurses (B5) who are junior grade nurses and Band 6 nurses (B6) who are clinical nurse specialists, Foundation Year and Core Medical Trainee doctors who are postgraduate interns (FY/CMT), General Practitioners (GP), Specialty doctors (SAS), Specialty Trainee Registrars years 3–6 (STR) who are resident doctors and consultants who are attending doctors.…”

“…Women diagnosed with, and treated for, PID at first presentation, as recorded in clinical case notes, were defined as PID cases. They were defined as CT infected if the endocervical swab or VVS was positive by AC2 and confirmed by Aptima CT,14 and as NG infected if positive on culture with biochemical confirmation for N. gonorrhoeae , or on endocervical or VVS AC2 confirmed by Aptima GC 13…”

Pelvic inflammatory disease in the adolescent

“…Research [60][61][62] notes that nucleic acid amplification analysis of vulvovaginal swabs taken by women ('self-taken swabs') is an excellent and noninvasive method of early chlamydia as well as gonorrhea detection.…”

Comparison of Azithromycin and Doxycycline in Treatment of Acute Uncomplicated Pelvic Inflammatory Disease

“…In fact there is no single conclusive test for PID however, various imaging, laboratory analysis and procedures can be performed to have the definitive diagnosis. [15][16][17] In any suspected case of PID it is recommended to use broad spectrum antibiotics empirically. Chosen antibiotics need to be effective against Chlamydia trachomatis, Neisseria gonorrhoeae, Gramnegative facultative organisms, Anaerobes, and Streptococci.…”