Comparing urine samples and cervical swabs for Chlamydia testing in a female population by means of Strand Displacement Assay (SDA)

<p>Abstract</p> <p>Background</p> <p>There has been an increasing number of diagnosed cases of <it>Chlamydia trachomatis </it>in many countries, in particular among young people. The present study was based on a growing request to examine urine as a supplementary or primary specimen in screening for <it>Chlamydia trachomatis </it>in women, with the Becton Dickinson ProbeTec (BDPT) Strand Displacement Assay (SDA). Urine samples may be particularly important in screening young people who are asymptomatic.</p> <p>Methods</p> <p>A total of 603 women aged 15 and older were enrolled from the Sexually Transmitted Infection (STI) clinic at Haukeland University Hospital, Norway, in 2007. Only 31 women were older than 35 years. Cervical swabs and urine samples were tested with BDPT for all participants. In cases of discrepant test results from a given patient, both samples were retested by Cobas TaqManCT and a Polymerase Chain Reaction (PCR)-method (in-house). Prevalence of <it>C. trachomatis</it>, sensitivity, and specificity were estimated by latent class analysis using all test results available. Bootstrap BC confidence intervals (10 000 computations) were estimated for sensitivity and specificity, and their differences in cervix vs. urine tests.</p> <p>Results</p> <p>A total of 1809 specimens were collected from 603 patients. 80 women (13.4%) were positive for <it>C. trachomatis</it>. Among these, BDPT identified 72 and 73 as positive in cervix and urine samples, respectively. Of the 523 <it>C. trachomatis </it>negative women, BDPT identified 519 as negative based on cervical swabs, and 514 based on urine samples. Sensitivity for cervical swabs and urine samples with the BDPT were 89.0% (95% CI 78.8, 98.6) and 90.2% (95% CI 78.1, 95.5), respectively. The corresponding values for specificity were 99.2% (95% CI 98.3, 100) and 98.3% (95% CI 96.4, 100).</p> <p>Conclusions</p> <p>This study indicates that urine specimens are adequate for screening high-risk groups for <it>C. trachomatis </it>by the SDA method (BDPT). Such an approach may facilitate early detection and treatment of the target groups for screening, and be cost-effective for patients and the health services.</p

Molecular diagnostics and characterization of Neisseria gonorrhoeae

Gonore er en sjelden infeksjon i Norge, men kan være en alvorlig infeksjon med fatalt utfall. Gonoreinfeksjon kan oppleves sosialt belastende. Blir en diagnostisert er behandlende lege pålagt å gjennomføre smitteoppsporing og alle seksuelle kontakter undersøkes. Tradisjonell diagnostikk er avhengig av å dyrke bakterien. Dessverre er gonorebakterien veldig skjør og kan lett dø etter prøvetaking og under transport til laboratoriet. I Nord-Norge er det spesielt problematisk med store avstander og lang transporttid. Den nye metoden baseres på deteksjon av DNA fra bakterien og er helt uavhengig av at de fortsatt er i live. I tillegg har metoden høy spesifisitet og sensitivitet og vil minimere både falske positive og falske negative resultater som ellers kan påføre mennesker unødige lidelser. Behandlingsresultat følges normalt opp med kontrollprøve og med ny diagnostikk, måtte vi også avgjøre riktig tidspunkt for å ta kontrollprøve etter behandling. Siden Norske retningslinjer for behandling av gonore var alvorlig utdatert, var det og viktig å kartlegge antibiotikaresistens, og andre karakteristikker ved den norske gonorestammene for å kunne foreslå effektiv behandling for pasientene

Appropriate Time for Test-of-Cure when Diagnosing Gonorrhoea with a Nucleic Acid Amplification Test

This article is part of Stig Ove Hjelmevolls doctoral thesis. Available in Munin at http://hdl.handle.net/10037/3816</a

A Fast Real-Time Polymerase Chain Reaction Method for Sensitive and Specific Detection of the Neisseria gonorrhoeae porA Pseudogene

Ever since the advent of molecular methods, the diagnostics of Neisseria gonorrhoeae has been troubled by false negative and false positive results compared with culture. Commensal Neisseria species and Neisseria meningitidis are closely related to N. gonorrhoeae and may cross-react when using molecular tests comprising too-low specificity. We have devised a real-time polymerase chain reaction (PCR), including an internal amplification control, that targets the N. gonorrhoeae porA pseudogene. DNA was automatically isolated on a BioRobot M48. Our subsequent PCR method amplified all of the different N. gonorrhoeae international reference strains (n = 34) and N. gonorrhoeae clinical isolates (n = 176) but not isolates of the 13 different nongonococcal Neisseria species (n = 68) that we tested. Furthermore, a panel of gram-negative bacterial (n = 18), gram-positive bacterial (n = 23), fungal (n = 1), and viral (n = 4) as well as human DNA did not amplify. The limit of detection was determined to be less than 7.5 genome equivalents/PCR reaction. In conclusion, the N. gonorrhoeae porA pseudogene real-time PCR developed in the present study is highly sensitive, specific, robust, rapid and reproducible, making it suitable for diagnosis of N. gonorrhoeae infection