title: Bacteria localization and chorion thinning among preterm premature rupture of membranes.
abstract: OBJECTIVE
  Bacterial colonization of the fetal membranes and its role in pathogenesis of membrane rupture is poorly understood. Prior retrospective work revealed chorion layer thinning in preterm premature rupture of membranes (PPROM) subjects. Our objective was to prospectively examine fetal membrane chorion thinning and to correlate to bacterial presence in PPROM, preterm, and term subjects.
  
  
  METHODS
  Paired membrane samples (membrane rupture and membrane distant) were prospectively collected from: PPROM = 14, preterm labor (PTL = 8), preterm no labor (PTNL = 8), term labor (TL = 10), and term no labor (TNL = 8), subjects. Sections were probed with cytokeratin to identify fetal trophoblast layer of the chorion using immunohistochemistry. Fluorescence in situ hybridization was performed using broad range 16 s ribosomal RNA probe. Images were evaluated, chorion and choriodecidua were measured, and bacterial fluorescence scored. Chorion thinning and bacterial presence were compared among and between groups using Student's t-test, linear mixed effect model, and Poisson regression model (SAS Cary, NC).
  
  
  RESULTS
  In all groups, the fetal chorion cellular layer was thinner at rupture compared to distant site (147.2 vs. 253.7 µm, p<0.0001). Further, chorion thinning was greatest among PPROM subjects compared to all other groups combined, regardless of site sampled [PPROM(114.9) vs. PTL(246.0) vs. PTNL(200.8) vs. TL(217.9) vs. TNL(246.5)]. Bacteria counts were highest among PPROM subjects compared to all other groups regardless of site sampled or histologic infection [PPROM(31) vs. PTL(9) vs. PTNL(7) vs. TL(7) vs. TNL(6)]. Among all subjects at both sites, bacterial counts were inversely correlated with chorion thinning, even excluding histologic chorioamnionitis (p<0.0001 and p = 0.05).
  
  
  CONCLUSIONS
  Fetal chorion was uniformly thinner at rupture site compared to distant sites. In PPROM fetal chorion, we demonstrated pronounced global thinning. Although cause or consequence is uncertain, bacterial presence is greatest and inversely correlated with chorion thinning among PPROM subjects.
authors.affiliation: Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Vanderbilt University, Nashville, Tennessee, United States of America.
authors.forename: Kimberly B
authors.initials: KB
authors.lastname: Fortner
authors.affiliation: Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, Duke University, Durham, North Carolina, United States of America.
authors.forename: Chad A
authors.initials: CA
authors.lastname: Grotegut
authors.affiliation: Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Vanderbilt University, Nashville, Tennessee, United States of America.
authors.forename: Carla E
authors.initials: CE
authors.lastname: Ransom
authors.affiliation: Department of Pathology, Duke University Hospital, Duke University, Durham, North Carolina, United States of America.
authors.forename: Rex C
authors.initials: RC
authors.lastname: Bentley
authors.affiliation: Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, Duke University, Durham, North Carolina, United States of America.
authors.forename: Liping
authors.initials: L
authors.lastname: Feng
authors.affiliation: Department of Biostatistics, Duke University Hospital, Duke University, Durham, North Carolina, United States of America.
authors.forename: Lan
authors.initials: L
authors.lastname: Lan
authors.affiliation: Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, Duke University, Durham, North Carolina, United States of America.
authors.forename: R Phillips
authors.initials: RP
authors.lastname: Heine
authors.affiliation: Division of Infectious Diseases, Department of Pediatrics, Duke University Hospital and Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Seed
authors.affiliation: Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, Duke University, Durham, North Carolina, United States of America.
authors.forename: Amy P
authors.initials: AP
authors.lastname: Murtha
mesh_terms: D000328:Adult; D000650:Amnion / Q000382:microbiology / Q000473:pathology; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification*; D002823:Chorion / Q000382:microbiology* / Q000473:pathology*; D015169:Colony Count, Microbial; D005322:Premature Rupture of Fetal Membranes / Q000382:microbiology* / Q000473:pathology*; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D016018:Least-Squares Analysis