title: Natural Course of Chlamydia trachomatis Bacterial Load in the Time Interval between Screening and Treatment in Anogenital Samples.
abstract: BACKGROUND
  Although Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection worldwide, little is known about the natural course of the bacterial load during infection. We investigated the natural course of the bacterial load in the interval between screening and returning for treatment in genital and anorectal CT-infections.
  
  
  METHODS
  CT-positive patients, visiting our STI-clinic in the Netherlands from June 2011-January 2014, provided a second urogenital and/or anorectal sample when returning for treatment (diagnostic sample = T1; treatment sample = T2). Patient-record provided data about the days between samples and the date of last unsafe sex. Included patients were ≥18 years old, HIV-negative and did not report antibiotic use in the study-interval. CT load was quantified using qPCR. CT load was log-transformed, and a CT load difference (Δ-CT load) of >1 log was deemed clinically relevant. Chi-square test compared load category distributions over time (decrease/equal/increase), between sample types.
  
  
  RESULTS
  274 patients provided 296 paired samples. Majority of samples had a stable CT load in the interval T1-T2 (66.3%, 73.1% and 48.6% for vaginal swabs, urine and anorectal swabs resp. p = 0.07). Load decreased in 17-41% of patients, while ±10% of patients showed an increase in CT load. No association between Δ-CT load and the interval T1-T2 was observed. Large variations can be seen in CT load at T1 and over time.
  
  
  CONCLUSIONS
  The majority (±90%) of patients have a stable or decreasing CT load in the time interval between screening and returning for treatment. The number of days between sampling was not associated with change in CT load. In the first month after the last unsafe sex, only stable CT loads were seen. Our data seems to indicate that when most patients visit an STI-clinic, recommended 2 weeks after infection, the infection has already been established or is in its downward phase.
authors.affiliation: Department of Medical Microbiology, Maastricht University Medical Center, School of Public Health and Primary Care, Maastricht, the Netherlands.|Department of Sexual Health, Infectious Diseases and Environmental Health, Public Health Service South Limburg, Geleen, the Netherlands.
authors.forename: J A M C
authors.initials: JA
authors.lastname: Dirks
authors.affiliation: Department of Medical Microbiology, Maastricht University Medical Center, School of Public Health and Primary Care, Maastricht, the Netherlands.|Department of Sexual Health, Infectious Diseases and Environmental Health, Public Health Service South Limburg, Geleen, the Netherlands.
authors.forename: G A F S
authors.initials: GA
authors.lastname: van Liere
authors.affiliation: Department of Medical Microbiology, Maastricht University Medical Center, School of Public Health and Primary Care, Maastricht, the Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Bogers
authors.affiliation: Department of Medical Microbiology, Maastricht University Medical Center, School of Public Health and Primary Care, Maastricht, the Netherlands.|Department of Sexual Health, Infectious Diseases and Environmental Health, Public Health Service South Limburg, Geleen, the Netherlands.
authors.forename: N H T M
authors.initials: NH
authors.lastname: Dukers-Muijrers
authors.affiliation: Department of Medical Microbiology, Maastricht University Medical Center, School of Public Health and Primary Care, Maastricht, the Netherlands.
authors.forename: P F G
authors.initials: PF
authors.lastname: Wolffs
authors.affiliation: Department of Medical Microbiology, Maastricht University Medical Center, School of Public Health and Primary Care, Maastricht, the Netherlands.|Department of Sexual Health, Infectious Diseases and Environmental Health, Public Health Service South Limburg, Geleen, the Netherlands.
authors.forename: C J P A
authors.initials: CJ
authors.lastname: Hoebe
mesh_terms: D000293:Adolescent; D000328:Adult; D001003:Anal Canal / Q000382:microbiology*; D058491:Bacterial Load; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000382:microbiology / Q000628:therapy*; D002692:Chlamydia trachomatis / Q000502:physiology*; D018450:Disease Progression; D005260:Female; D005836:Genitalia, Female / Q000382:microbiology*; D006801:Humans; D008875:Middle Aged; D012007:Rectum / Q000382:microbiology*; D047568:Unsafe Sex; D055815:Young Adult