title: The Epidemiology of Chlamydia trachomatis Organism Load During Genital Infection: A Systematic Review.
abstract: BACKGROUND
  The role of organism load in Chlamydia trachomatis infection is not well understood. We conducted a systematic review to investigate the epidemiology of C. trachomatis organism load in human genital chlamydia infection.
  
  
  METHODS
  Embase, PubMed, and Medline databases were searched for literature published through August 2014. English-language publications that quantified load in humans were eligible. Participant characteristics and laboratory data were extracted.
  
  
  RESULTS
  A total of 737 records were identified, and 29 publications involving 40 883 participants were included. In women, load was highest for cervical swabs and lowest for urine specimens. In men, load was highest for rectal swabs and similar for urethral swabs and urine specimens. Evidence of any association between load and age, serovar, risk of transmission, hormone levels, and concurrent sexually transmitted infections was inconsistent. Eight of 9 culture-based studies found an association between load and signs and symptoms, in contrast with only 3 of 8 nucleic acid amplification test (NAAT)-based studies (P = .03).
  
  
  CONCLUSIONS
  Chlamydia organism load varies by specimen type and site of sampling, and viable chlamydia organism load may be a more important indicator of severity of infection than total load measured by NAAT.
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne Melbourne Sexual Health Centre, Carlton Murdoch Children's Research Institute, Parkville.
authors.forename: Lenka A
authors.initials: LA
authors.lastname: Vodstrcil
authors.affiliation: Sydney Sexual Health Centre, South Eastern Sydney Local Health District, Sydney.
authors.forename: Ruthy
authors.initials: R
authors.lastname: McIver
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane.
authors.forename: Wilhelmina M
authors.initials: WM
authors.lastname: Huston
authors.affiliation: Murdoch Children's Research Institute, Parkville Department of Obstetrics and Gynaecology, University of Melbourne, The Royal Women's Hospital.
authors.forename: Sepehr N
authors.initials: SN
authors.lastname: Tabrizi
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane University of the Sunshine Coast, Sippy Downs, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Timms
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne.
authors.forename: Jane S
authors.initials: JS
authors.lastname: Hocking
mesh_terms: D058491:Bacterial Load; D002690:Chlamydia Infections / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology*; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D008297:Male; D060737:Reproductive Tract Infections / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology*; D012720:Severity of Illness Index
keywords: Chlamydia trachomatis; culture; nucleic acid amplification; organism load; systematic review