title: Chlamydia related bacteria (Chlamydiales) in early pregnancy: community-based cohort study.
abstract: OBJECTIVE
  Serological case-control studies suggest that certain chlamydia-related bacteria (Chlamydiales) which cause cows to abort may do the same in humans. Chlamydiales include Waddlia chondrophila, Chlamydia abortus and Chlamydia trachomatis. Data on prevalence of Chlamydiales in pregnancy are sparse. Using stored urine samples from a carefully characterised cohort of 847 newly pregnant women recruited from 37 general practices in London, UK, we aimed to investigate the prevalence and types of Chlamydiales infections. We also explored possible associations with miscarriage or spontaneous preterm birth.
  
  
  METHODS
  Samples were tested using W. chondrophila and pan-Chlamydiales specific real-time PCRs targeting the 16S rRNA gene. Samples positive on either PCR were subjected to DNA sequencing and C. trachomatis PCR.
  
  
  RESULTS
  The overall prevalence of Chlamydiales was 4.3% (36/847, 95% CI 3.0% to 5.8%). The prevalence of W. chondrophila was 0.6% (n = 5), C. trachomatis 1.7% (n = 14), and other Chlamydiales species 2.0% (n = 17). Infection with C. trachomatis was more common in women aged <25, of black ethnicity or with bacterial vaginosis, but this did not apply to W. chondrophila or other Chlamydiales. Follow up was 99.9% at 16 weeks gestation and 90% at term. No infection was significantly associated with miscarriage at ≤12 weeks (prevalence 10%, 81/827) or preterm birth <37 weeks (prevalence 4%, 23/628). Of 25 samples sequenced, seven (28%) were positive for Chlamydiales bacterium sequences associated with respiratory tract infections in children.
  
  
  CONCLUSIONS
  In the first study to use the pan-Chlamydiales assay on female urine samples, 4% of pregnant women tested positive for Chlamydiales, including species known to be pathogenic in mothers and neonates.
authors: Department of Primary Care and Public Health Sciences, King's College London, London, UK.
authors: F
authors: F
authors: Reid
authors: Population Health Research Institute, St George's, University of London, London, UK. Electronic address: oakeshot@sgul.ac.uk.
authors: P
authors: P
authors: Oakeshott
authors: Population Health Research Institute, St George's, University of London, London, UK.
authors: S R
authors: SR
authors: Kerry
authors: Courtyard Genitourinary Medicine Clinic, St George's NHS Trust, London, UK.
authors: P E
authors: PE
authors: Hay
authors: Statens Serum Institut, Copenhagen, Denmark.
authors: J S
authors: JS
authors: Jensen
mesh_terms: D000022:Abortion, Spontaneous / Q000209:etiology; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002689:Chlamydia / Q000145:classification / Q000235:genetics; D002694:Chlamydiaceae Infections / Q000453:epidemiology* / Q000382:microbiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology* / Q000382:microbiology*; D047928:Premature Birth; D015995:Prevalence; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012307:Risk Factors; D055815:Young Adult
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: Chlamydiales; Cohort study; Miscarriage; Pregnancy; Preterm birth; Prevalence