title: Differing prevalence and diversity of bacterial species in fetal membranes from very preterm and term labor.
abstract: BACKGROUND
  Intrauterine infection may play a role in preterm delivery due to spontaneous preterm labor (PTL) and preterm prolonged rupture of membranes (PPROM). Because bacteria previously associated with preterm delivery are often difficult to culture, a molecular biology approach was used to identify bacterial DNA in placenta and fetal membranes.
  
  
  RESULTS
  We used broad-range 16S rDNA PCR and species-specific, real-time assays to amplify bacterial DNA from fetal membranes and placenta. 74 women were recruited to the following groups: PPROM <32 weeks (n = 26; 11 caesarean); PTL with intact membranes <32 weeks (n = 19; all vaginal birth); indicated preterm delivery <32 weeks (n = 8; all caesarean); term (n = 21; 11 caesarean). 50% (5/10) of term vaginal deliveries were positive for bacterial DNA. However, little spread was observed through tissues and species diversity was restricted. Minimal bacteria were detected in term elective section or indicated preterm deliveries. Bacterial prevalence was significantly increased in samples from PTL with intact membranes [89% (17/19) versus 50% (5/10) in term vaginal delivery p = 0.03] and PPROM (CS) [55% (6/11) versus 0% (0/11) in term elective CS, p = 0.01]. In addition, bacterial spread and diversity was greater in the preterm groups with 68% (13/19) PTL group having 3 or more positive samples and over 60% (12/19) showing two or more bacterial species (versus 20% (2/10) in term vaginal deliveries). Blood monocytes from women with PTL with intact membranes and PPROM who were 16S bacterial positive showed greater level of immune paresis (p = 0.03). A positive PCR result was associated with histological chorioamnionitis in preterm deliveries.
  
  
  CONCLUSIONS
  Bacteria are found in both preterm and term fetal membranes. A greater spread and diversity of bacterial species were found in tissues of women who had very preterm births. It is unclear to what extent the greater bacterial prevalence observed in all vaginal delivery groups reflects bacterial contamination or colonization of membranes during labor. Bacteria positive preterm tissues are associated with histological chorioamnionitis and a pronounced maternal immune paresis.
authors.affiliation: Infectious Diseases and Microbiology Unit, Institute of Child Health, London, United Kingdom. h.jones@ich.ucl.ac.uk
authors.forename: Hannah E
authors.initials: HE
authors.lastname: Jones
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Harris
authors.forename: Malika
authors.initials: M
authors.lastname: Azizia
authors.forename: Lindsay
authors.initials: L
authors.lastname: Bank
authors.forename: Bernadette
authors.initials: B
authors.lastname: Carpenter
authors.forename: John C
authors.initials: JC
authors.lastname: Hartley
authors.forename: Nigel
authors.initials: N
authors.lastname: Klein
authors.forename: Donald
authors.initials: D
authors.lastname: Peebles
mesh_terms: D000328:Adult; D001419:Bacteria / Q000302:isolation & purification*; D044822:Biodiversity; D002821:Chorioamnionitis / Q000473:pathology; D005321:Extraembryonic Membranes / Q000382:microbiology* / Q000473:pathology; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000276:immunology / Q000382:microbiology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000382:microbiology / Q000473:pathology; D007743:Labor, Obstetric / Q000502:physiology*; D007752:Obstetric Labor, Premature / Q000382:microbiology*; D010920:Placenta / Q000382:microbiology / Q000473:pathology; D011247:Pregnancy; D047928:Premature Birth / Q000382:microbiology; D055815:Young Adult
chemical_list: D000949:Histocompatibility Antigens Class II