TY - JOUR
T1 - Widespread microbial invasion of the chorioamniotic membranes is a consequence and not a cause of intra-amniotic infection
AU - Kim, Mi Jeong
AU - Romero, Roberto
AU - Gervasi, Maria Teresa
AU - Kim, Jung Sun
AU - Yoo, Wonsuk
AU - Lee, Deug Chan
AU - Mittal, Pooja
AU - Erez, Offer
AU - Kusanovic, Juan Pedro
AU - Hassan, Sonia S.
AU - Kim, Chong Jai
N1 - Funding Information:
This research was supported (in part) by the Perinatology Research Branch, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, DHHS.
PY - 2009/8
Y1 - 2009/8
N2 - Acute chorioamnionitis is a response to amniotic fluid (AF) infection. However, it remains unclear whether substantial bacterial propagation in the chorioamniotic membranes (CAMs) precedes microbial invasion of the amniotic cavity (MIAC), which is inconsistent with characteristic amniotropic neutrophil migration in acute chorioamnionitis. This study was performed to determine whether CAMs have widespread bacterial infection during MIAC and whether bacteria normally colonize CAMs. AF pellets and CAMs from the following groups were studied: group 1, patients with positive (n18) or negative (n22) AF cultures; group 2, patients with or without acute chorioamnionitis in which the amnion and chorion were studied separately (n60); and group 3, patients at term who underwent a cesarean delivery (n30). SYTO 9/propidium iodide fluorescent staining and fluorescent in situ hybridization for 16S rRNA were performed. Real-time quantitative PCR for 16S rDNA and PCR for genital mycoplasmas were also conducted. Bacteria were more frequently detected in AF than in CAMs of patients with positive AF culture (100 vs. 33%; P0.0001). Bacteria were detected more frequently in CAMs as the severity of chorioamnionitis increased (P0.01). The median 16S rRNA gene copy number in the amnion was significantly greater than in the chorion (group 2; P0.0001). Bacteria were not detected in CAMs or AF in women at term before labor (group 3). A fraction of patients with chorioamnionitis or MIAC did not have bacteria in CAMs. Collectively, the findings herein indicate that MIAC does not follow widespread infection of CAMs, but precedes it. We propose a model of MIAC: the initial stage is intra-amniotic bacterial invasion through a discrete region of the CAMs, followed by intra-amniotic proliferation, and bacterial invasion of CAMs primarily extends from the amniotic fluid. This study emphasizes the importance of assessing the intra-amniotic compartment for diagnosis and treatment of preterm birth.
AB - Acute chorioamnionitis is a response to amniotic fluid (AF) infection. However, it remains unclear whether substantial bacterial propagation in the chorioamniotic membranes (CAMs) precedes microbial invasion of the amniotic cavity (MIAC), which is inconsistent with characteristic amniotropic neutrophil migration in acute chorioamnionitis. This study was performed to determine whether CAMs have widespread bacterial infection during MIAC and whether bacteria normally colonize CAMs. AF pellets and CAMs from the following groups were studied: group 1, patients with positive (n18) or negative (n22) AF cultures; group 2, patients with or without acute chorioamnionitis in which the amnion and chorion were studied separately (n60); and group 3, patients at term who underwent a cesarean delivery (n30). SYTO 9/propidium iodide fluorescent staining and fluorescent in situ hybridization for 16S rRNA were performed. Real-time quantitative PCR for 16S rDNA and PCR for genital mycoplasmas were also conducted. Bacteria were more frequently detected in AF than in CAMs of patients with positive AF culture (100 vs. 33%; P0.0001). Bacteria were detected more frequently in CAMs as the severity of chorioamnionitis increased (P0.01). The median 16S rRNA gene copy number in the amnion was significantly greater than in the chorion (group 2; P0.0001). Bacteria were not detected in CAMs or AF in women at term before labor (group 3). A fraction of patients with chorioamnionitis or MIAC did not have bacteria in CAMs. Collectively, the findings herein indicate that MIAC does not follow widespread infection of CAMs, but precedes it. We propose a model of MIAC: the initial stage is intra-amniotic bacterial invasion through a discrete region of the CAMs, followed by intra-amniotic proliferation, and bacterial invasion of CAMs primarily extends from the amniotic fluid. This study emphasizes the importance of assessing the intra-amniotic compartment for diagnosis and treatment of preterm birth.
KW - 16S rRNA
KW - Amniotic fluid
KW - Chorioamnionitis
KW - Fluorescent in situ hybridization
KW - Intra-amniotic infection
KW - Polymerase chain reaction
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U2 - 10.1038/labinvest.2009.49
DO - 10.1038/labinvest.2009.49
M3 - Article
C2 - 19506551
AN - SCOPUS:68149164687
SN - 0023-6837
VL - 89
SP - 924
EP - 936
JO - Laboratory Investigation
JF - Laboratory Investigation
IS - 8
ER -