title: Time to clearance of Chlamydia trachomatis RNA and DNA after treatment in patients coinfected with Neisseria gonorrhoeae - a prospective cohort study.
abstract: Performing a test of cure (TOC) could demonstrate success or failure of antimicrobial treatment of Chlamydia trachomatis infection, but recommendations for the timing of a TOC using nucleic acid amplification tests (NAATs) are inconsistent. We assessed time to clearance of C. trachomatis after treatment, using modern RNA- and DNA-based NAATs.
  
  
  
  We analysed data from patients with a C. trachomatis and Neisseria gonorrhoeae coinfection who visited the STI Clinic Amsterdam, The Netherlands, from March through October 2014. After treatment with ceftriaxone plus either azithromycin or doxycycline, patients self-collected anal, vaginal or urine samples during 28 consecutive days. Samples were analysed using an RNA-based NAAT (Aptima Combo 2) and a DNA-based NAAT (Cobas 4800 CT/NG). We defined clearance as three consecutive negative results, and defined "blips" as isolated positive results following clearance.
  
  
  
  We included 23 patients with C. trachomatis and N. gonorrhoeae coinfection. All patients cleared C. trachomatis during follow-up, and we observed no reinfections. The median time to clearance (range) was 7 days (1-13) for RNA, and 6 days (1-15) for DNA. Ninety-five per cent of patients cleared RNA at day 13, and DNA at day 14. The risk of a blip after clearance was 4.4 % (RNA) and 1.7 % (DNA).
  
  
  
  If a TOC for anogenital chlamydia is indicated, we recommend performing it at least 14 days after initiation of treatment, when using modern RNA- and DNA-based assays. A positive result shortly after 14 days probably indicates a blip, rather than a treatment failure or a reinfection.
authors.affiliation: STI Outpatient Clinic, Department of Infectious Diseases, Public Health Service Amsterdam, PO Box 2200, 1000 CE, Amsterdam, The Netherlands.|Department of Dermatology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Carolien M
authors.initials: CM
authors.lastname: Wind
authors.affiliation: Department of Infectious Diseases, Public Health Service Amsterdam, PO Box 2200, 1000 CE, Amsterdam, The Netherlands.|Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Maarten F
authors.initials: MF
authors.lastname: Schim van der Loeff
authors.affiliation: WHO Collaborating Centre for Gonorrhoea and Other STIs, National Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Microbiology, Örebro University, SE-701 85, Örebro, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Unemo
authors.affiliation: Department of Medical Microbiology, University Medical Centre Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: Schuurman
authors.affiliation: Public Health Laboratory, Public Health Service Amsterdam, Amsterdam, The Netherlands.|Department of Medical Microbiology, Onze Lieve Vrouwe Gasthuis General Hospital, Amsterdam, The Netherlands.
authors.forename: Alje P
authors.initials: AP
authors.lastname: van Dam
authors.affiliation: STI Outpatient Clinic, Department of Infectious Diseases, Public Health Service Amsterdam, PO Box 2200, 1000 CE, Amsterdam, The Netherlands. h.j.devries@amc.uva.nl.|Department of Dermatology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. h.j.devries@amc.uva.nl.|Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. h.j.devries@amc.uva.nl.
authors.forename: Henry J C
authors.initials: HJ
authors.lastname: de Vries
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D017963:Azithromycin / Q000008:administration & dosage; D015415:Biomarkers / Q000652:urine; D002443:Ceftriaxone / Q000008:administration & dosage; D002690:Chlamydia Infections / Q000188:drug therapy / Q000382:microbiology* / Q000652:urine; D002692:Chlamydia trachomatis / Q000235:genetics; D060085:Coinfection / Q000188:drug therapy / Q000382:microbiology* / Q000652:urine; D004269:DNA, Bacterial / Q000235:genetics / Q000652:urine; D004318:Doxycycline / Q000008:administration & dosage; D004359:Drug Therapy, Combination; D005260:Female; D006069:Gonorrhea / Q000188:drug therapy / Q000382:microbiology* / Q000652:urine; D006801:Humans; D008297:Male; D025202:Molecular Diagnostic Techniques; D009344:Neisseria gonorrhoeae / Q000235:genetics; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D011446:Prospective Studies; D012329:RNA, Bacterial / Q000235:genetics / Q000652:urine; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D015415:Biomarkers; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D002443:Ceftriaxone; D017963:Azithromycin; D004318:Doxycycline
keywords: Antimicrobial resistance; Chlamydia trachomatis; Neisseria gonorrhoeae; Nucleic acid amplification test; Test of cure