Rapid in vitro Replication of Group B Streptococcus in Term Human Amniotic Fluid

Hemming, Val G.; Nagarajan, K.; Hess, Leandra; Fischer, GeraldW.; Wilson, Samuel; Thomas, Lamar S.

doi:10.1159/000299021

Cited by 17 publications

(5 citation statements)

References 9 publications

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“…It is possible, however, that if amnion cells are actively being sloughed off into the amniotic fluid, any adherent GBS may passively acquire access to the amnion. Only a minimal number of CFU would need to penetrate the entire membrane, since the amniotic fluid has been shown to provide an excellent growth medium for rapid GBS replication (18,38). Alternatively, once the organism gains access to the membrane stroma, GBS colonization may induce a host inflammatory response which could affect amnion epithelial integrity, allowing GBS to breach this barrier.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Group B Streptococcal Invasion of Human Chorion and Amnion Epithelial Cells In Vitro

et al. 1998

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Group B streptococci (GBS) have been cultured from the chorioamnionic membrane of pregnant women, usually in association with chorioamnionitis and premature labor (K. A. Boggess, D. H. Watts, S. L. Hillier, M. A. Krohn, T. J. Benedetti, and D. A. Eschenbach, Obstet. Gynecol. 87:779–784, 1996). Colonization and infection of placental membranes can be a prelude to neonatal GBS infections even in the presence of intact membranes (R. L. Naeye and E. C. Peters, Pediatrics61:171–177, 1978), suggesting that GBS cause chorioamnionitis or establish amniotic fluid infections by partial or complete penetration of the placental membranes. We have isolated and grown cultures of primary chorion and amnion cells from human cesarean-section placentas. This has provided a biologically relevant model for investigating GBS adherence to and invasion of the two epithelial barriers of the placental membrane. GBS adhered to chorion cell monolayers to a high degree. Pretreatment of GBS with trypsin reduced adherence up to 10-fold, which suggested that the bacterial ligand(s) was a protein. GBS invaded chorion cells at a high rate in vitro, and invasion was dependent on cellular actin polymerization. GBS could be seen within intracellular vacuoles of chorion cells by transmission electron microscopy. We also demonstrated that GBS were capable of transcytosing through intact chorion cell monolayers without disruption of intracellular junctions. GBS also adhered to amnion cells; in contrast, however, these bacteria failed to invade amnion cells under a variety of assay conditions. GBS interactions with the chorion epithelial cell layer shown here correlate well with epidemiological and pathological studies of GBS chorioamnionitis. Our data also suggest that the amnion cell layer may provide an effective barrier against infection of the amniotic fluid.

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Section: Discussionmentioning

confidence: 99%

Characterization of Group B Streptococcal Invasion of Human Chorion and Amnion Epithelial Cells In Vitro

et al. 1998

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“…Finally, to determine if the growth of GBS in HAF caused the release of antigens which would allow the detection of a smaller number of organisms, we used a modification of the method of Hemming et al (6). Briefly, GBS was inoculated into sterile HAF to a concentration of 102 organisms per ml.…”

Section: Methodsmentioning

confidence: 99%

Rapid detection of group B streptococcal antigen in human amniotic fluid

Moriarty¹,

Smith²,

Hemming³

et al. 1987

J Clin Microbiol

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Infants exposed in utero to group B streptococcus (GBS)-infected human amniotic fluid (HAF) are at high risk for serious infection. Latex particle agglutination (LPA) tests are not approved for detection of GBS in HAF. Two LPA systems, Patho-Dx Strep B and Wellcogen Strep B, were used to test unfiltered sterile HAF and filtered HAF containing concentrations of GBS carbohydrate from 0.2 to 100 ,ug/ml. Four different processing techniques were used to prevent nonspecific LPA: EDTA, nitrous acid, enzyme, and nitrous acid-heat. GBS (102 CFU/ml) was inoculated into filtered HAF, incubated, sampled serially, processed with enzyme, and tested by LPA. Unprocessed, unfiltered HAF showed 33% nonspecific agglutination when tested by LPA. Processing of HAF removed nonspecific agglutination and improved GBS antigen detection. Without processing, LPA could not detect less than 100 ,g of GBS carbohydrate per ml. With nitrous acid or enzyme processing, as little as 0.2 ,ug/ml could be detected. Results were easier to read after enzyme processing than after nitrous acid processing. Although both LPA systems were equally efficient, testing was easier with the Patho-Dx system. After enzyme processing, LPA could detect as few as 104 CFU/ml when agglutination was read with a 4 x hand lens. Substances in HAF induce false-positive reactions during LPA testing. Processing removes the interference and improves the detection of GBS. LPA testing of HAF may allow earlier identification and treatment of infants at risk for serious GBS infection.

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“…GBS invade primary chorion cells efficiently in vitro and are capable of transcytosing through intact chorion cell monolayers without disruption of intracellular junctions [204]. Amniotic fluid supports the proliferation of GBS [206], such that when the organism gains access to the uterine cavity a large inoculum can be delivered to the fetal lung; this results in a continuum of intrapartum (stillbirth) to early postpartum infant death [176,[207][208][209][210][211]. Amniotic fluid supports the proliferation of GBS [206], such that when the organism gains access to the uterine cavity a large inoculum can be delivered to the fetal lung; this results in a continuum of intrapartum (stillbirth) to early postpartum infant death [176,[207][208][209][210][211].…”

Section: Ascending Amniotic Infectionmentioning

confidence: 99%