Use of Pooled Urine Samples and Automated DNA Isolation To Achieve Improved Sensitivity and Cost-Effectiveness of Large-Scale Testing for Chlamydia trachomatis in Pregnant Women

Abstract

The success of large-scale screening for Chlamydia trachomatis depends on the availability of noninvasive samples, low costs, and high-quality testing. To evaluate C. trachomatis testing with pregnant women, first-void urine specimens from 750 consecutive asymptomatic pregnant women from the Rotterdam area (The Netherlands) were collected. Initially, we investigated the performance of three different DNA isolation methods with 350 of these urines and 70 pools of 5 of the same subset of urine samples. The routinely used COBAS AMPLICOR test was compared to the COBAS AMPLICOR test with prior DNA isolation by use of the MagNA Pure large-volume kit and the MagNA Pure bacterial DNA isolation kit. The latter combination provided the best DNA test for pooled urines, with a sensitivity twice that of the other methods. Next, using all 750 urines, the COBAS AMPLICOR performance for individual testing was compared to pooled testing with the standard COBAS AMPLICOR procedure and subsequently to pooled testing with COBAS AMPLICOR in combination with the MagNA Pure bacterial DNA isolation kit. The sensitivity of COBAS AMPLICOR was 65% on individual and 42% on pooled urines but improved to 92% on pooled urines with the MagNA Pure bacterial DNA isolation kit, making this combination the best screening method. The C. trachomatis prevalence in this population appeared to be 6.4%. Additionally, the cost of the combined MagNA Pure bacterial DNA isolation kit and COBAS AMPLICOR method on pooled urines was only 56% of the cost of the standard COBAS AMPLICOR test applied to individual urines. Costs per positive case detected in the combined method were 39% of standard costs.Chlamydia trachomatis is one of the major sexually transmitted pathogens, and high prevalences of chlamydial infection have been documented for asymptomatic women in many European countries (34). Asymptomatic carriers are of substantial importance in the transmission of C. trachomatis infection within a community. Asymptomatic chlamydial infection in pregnant women imposes an additional risk for acute and chronic consequences for the women themselves and their (unborn) offspring (2,6,8,9,16). In The Netherlands, C. trachomatis causes most sexually transmitted infections, with approximately 60,000 new cases estimated for a total population of 16 million in the year 2000. Studies in general practice have shown an increase in the incidence of chlamydial infections (26), but data covering other specific target groups outside of the sexually transmitted disease (STD) outpatient clinics are sparse (1). Dutch population-based screening for C. trachomatis is still under debate, with cost-effectiveness of screening, complexity of sampling, the reliability of test methods, and the nature of the target population as major issues of discussion (23).In order to investigate the prevalence of chlamydial infection during pregnancy in Rotterdam, and the risk factors and consequences of chlamydial infection during pregnancy for women and newborns, a follow-up study was planned. We ex...

Chlamydia trachomatis as a Cause of Neonatal Conjunctivitis in Dutch Infants

“…Previously we described the costs of chlamydia screening of pregnant women by different DNA-isolation methods in individual and pooled urine samples. 16 The cost per chlamydia case detected when using the Cobas Amplicor on individual urine samples was €275 and when using a combined method of isolation with the MagNA Pure bacterial DNA-isolation kit (Roche Molecular Diagnostics, Pleasanton, CA), and subsequent amplification and detection by Cobas Amplicor on pooled urine samples, as we did, was €108.…”

“…16 To prevent 1 case of chlamydial conjunctivitis, 31 to 78 pregnant women need to be screened. Assuming a specificity of Ն99.8%, 16 this could result in 0.06 to 0.16 false-positive mothers and 2 to 5 truly positive mothers (and their partners); furthermore, this could result in the prevention of 1.4 to 2.5 nasopharyngitis cases and 0.2 to 1.0 pneumonia cases. Previously we described the costs of chlamydia screening of pregnant women by different DNA-isolation methods in individual and pooled urine samples.…”

“…14,15 Recently we reported a prevalence of C trachomatis infection in pregnant women of 6.4%. 16 Most of these infections had been missed in routine care, suggesting that C trachomatis transmission to infants may often remain unnoticed.…”

The Generation R Study: design and cohort update 2012

“…These urine samples are used for measurement of several environmental exposures, and metabolites. Urine samples have been used for measurement of Chlamydia, and pesticides, bisphenol A, and phthalates levels [155,156].…”

Chlamydia trachomatis Infection and Reproductive Health Outcomes in Women

“…Self-collected vaginal swabs and first-void urine are samples that are widely accepted by women (12), and can be collected in-house and mailed to laboratories, thus facilitating epidemiological studies and screening programmes in asymptomatic women. In addition, urine allows samples to be grouped into pools and increases the cost-effectiveness of studies, with little reduction in sensitivity (77). A large German study, using 5 urine pools, obtained a negative predictive value of 98.1% for the pooling system (14).…”