title: Chlamydia trachomatis load in population-based screening and STI-clinics: implications for screening policy.
abstract: OBJECTIVE
  If the Chlamydia trachomatis (CT) bacterial load is higher in high-risk populations than in the general population, this negatively affects the efficacy of CT screening incentives. In the largest retrospective study to date, we investigated the CT load in specimens collected from 2 cohorts: (1) attendants of a sexually transmitted infection (STI)-clinic and (2) participants of the Dutch population-based screening (PBS).
  
  
  METHODS
  CT load was determined using quantitative PCR in CT-positive male urine and female cervicovaginal swabs. CT loads were converted into tertiles. Using multinominal logistic regression, independent association of cohort, symptoms, risk behaviour and human cell count on load were assessed.
  
  
  RESULTS
  CT loads were determined in 889 CT-positives from PBS (n = 529; 71.8% female) and STI-clinics (n = 360; 61.7% female). In men, STI-clinic-cohort, human cell count and urethral discharge were positively associated with CT load. In women, PBS-cohort and cell count were positively associated with CT load. Both cohorts had the same range in CT load.
  
  
  CONCLUSIONS
  The general population has a similar range of bacterial CT load as a high-risk population, but a different distribution for cohort and gender, highlighting the relevance of population-based CT-screening. When CT loads are similar, possibly the chances of transmission and sequelae are too.
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: Jeanne 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.
authors.forename: Petra 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: Nicole 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: Antoinette A T P
authors.initials: AA
authors.lastname: Brink
authors.affiliation: Medical Microbiology Laboratory, Public Health Service Amsterdam, Amsterdam, The Netherlands.
authors.forename: Arjen G C L
authors.initials: AG
authors.lastname: Speksnijder
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: Christian J P A
authors.initials: CJ
authors.lastname: Hoebe
mesh_terms: D000293:Adolescent; D000328:Adult; D000554:Ambulatory Care Facilities; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000382:microbiology; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000458:organization & administration*; D016134:Organizational Policy; D012749:Sexually Transmitted Diseases / Q000175:diagnosis* / Q000382:microbiology; D055815:Young Adult
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