The role of bacterial vaginosis as a cause of amniotic fluid infection, chorioamnionitis and prematurity — a review

Abstract

Antepartum bacterial vaginosis in pregnancy has been related to premature delivery, the recovery of microorganisms from amniotic fluid of women in premature labor with intact membranes, to histologic chorioamnionitis and to the recovery of microorganisms from the placenta or membranes. Microorganisms associated with bacterial vaginosis are commonly recovered from the amniotic fluid and chorioamnion of patients who deliver prematurely. In addition, bacterial vaginosis is associated with maternal infectious morbidity during labor and in the postpartum period. Very little is known of the pathophysiologic mechanisms by which bacterial vaginosis may cause preterm labor and/or premature rupture of the membranes. However, it is of interest to speculate on possible mechanisms. The high concentration of potentially pathogenic microorganisms in the vagina and cervix of pregnant women with bacterial vaginosis may increase the possibility of an ascending infection via the cervix, decidua, fetal membranes, maternal placenta, and amniotic fluid. Some of the bacteria associated with bacterial vaginosis such as Bacteroides sp. are particularly virulent. Certain bacteria produce enzymes that potentially could affect the fetal membranes or maternal deciduae. Bacteroides sp. and group B streptococcus produce proteases. Protease enzymes reduce the chorioamniotic membrane strength in vitro. It is even possible that a high concentration of bacteria in the lower genital tract could produce enough proteases to weaken the fetal membrane strength causing premature rupture of the membranes. Bacterial lipases could also produce tissue injury. Schwarz et al. demonstrated that lysosomes within fetal membrane cells contain phospholipase A2 in high concentrations. Phospholipase A2 is a precursor of prostaglandin synthesis and the destruction of lysosomes within deciduae or chorioamnion cells may induce prostaglandin synthesis resulting in uterine contractions. Bejar et al. found a high rate of phospholipase A2 production by Bacteroides sp., anaerobic streptococci, Fusobacterium sp., and G. vaginalis. Benett et al. demonstrated that bacterial products of group B streptococci, viridans streptococci, Escherichia coli and Bacteroides fragilis but not of Lactobacillus sp. increase the synthesis of prostaglandins in the membranes. Thus, selected bacteria, including some closely related to bacterial vaginosis may play a role in the initiation of uterine contractions by stimulating prostaglandin synthesis. In an alternative mechanism, either the release of prostaglandin in the membrane or uterine contraction could cause microbreaks of the membrane that allow bacterial colonization of the membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Endotoxin-Neutralizing Antimicrobial Proteins of the Human Placenta

“…Although the etiology of preterm labor and delivery is unknown, there is overwhelming epidemiological, pathological, and immunological evidence to implicate the infection of the uteroplacental unit as a causative factor in a substantial number of preterm births (10 -12). Infection-related prematurity is most likely caused by an infection that ascends from the lower genital tract to the upper tract, with the end stage being a positive amniotic fluid culture (13,14). Fetal exposure to high concentrations of microorganisms leads to colonization of the fetus lung airways and subsequent pneumonia, sepsis, and meningitis (15,16).…”

Hypertension lead to Histo pathological changes in Placenta of PIH

“…& Eschenbach, D.A found that the role of bacterial vaginosis as a cause of amniotic fluid infection, chorioamnionitis and prematurity [10] .…”

Ultrastructural Characteristics ofGardnerella vaginalisInfection in the Heterosexual Couple

“…In recent years a renewed interest has emerged about vaginal infections with Gardnerella vaginalis, particularly in relation to its association with perinatal diseases [4,8,16,201. This bacteria is found in 24 to 37% of patients attending sexually transmitted diseases clinics and is most prevalent in individuals between 20 and 24 years of age .…”