Diagnosis of intrauterine infection by demonstration of antibody-coated bacteria in the amniotic fluid

An immunohistochemical study of the secretory immune system in human fetal membranes and decidua of the first trimester of pregnancy

PROBLEM

We analyzed the presence and distribution of components of the secretory immune system (SIS) in human fetal membranes (amnion, yolk sac, chorion) and decidua from the first trimester of pregnancy.

MATERIALS AND METHODS

Specimens from 17 embryos (4-8 weeks of pregnancy) and nine fetuses (9-12 weeks) were divided into those that had not been exposed to massive foreign antigenic effects (Group I, n = 18) and those that had suffered acute chorioamnionitis (Group II, n = 8).

RESULTS

Positive immunostaining for secretory component (SC), joining (J) chain, IgG, IgA, and macrophages was seen from 4 to 5 weeks of development and then during the whole first trimester of pregnancy in the syncytio- and cytotrophoblasts, the amniotic epithelium, the yolk sac endoderm and decidual cells. Macrophages with J chain, IgG and IgA were found in embryonic tissues on week 4, whereas lymphocytes, including those synthesizing IgA and IgM, appeared only at the end of the first trimester of pregnancy. In the decidua, lymphocytes and macrophages were recognized during the whole period of study. In cases with chorioamnionitis (Group II), reactivity of IgG and IgA in the mentioned cells of fetuses decreased sharply while the rate of immunoreactivity of SC and J chain as well as the number of T and B lymphocytes did not change. In the decidua, the number of immune reactive cells sharply increased with the appearance of plasma cells.

CONCLUSIONS

In the fetal membranes and decidua all the SIS components are present. We suggest that two SIS, maternal and fetal, participate in the formation of the barrier between a mother and the fetus. Both these systems have different origin and cellular content as well as different immune reactions.

Gardnerella vaginalis: characteristics, clinical considerations, and controversies

The clinical significance, Gram stain reaction, and genus affiliation of Gardnerella vaginalis have been controversial since Gardner and Dukes described the organism as the cause of "nonspecific vaginitis," a common disease of women which is now called bacterial vaginosis. The organism was named G. vaginalis when taxonomic studies showed that it was unrelated to bacteria in various genera including Haemophilus and Corynebacterium. Electron microscopy and chemical analyses have elucidated the organism's gram-variable reaction. Controversy over the etiology of bacterial vaginosis was largely resolved by (i) studies using improved media and methods for the isolation and identification of bacteria in vaginal fluids and (ii) standardization of criteria for clinical and laboratory diagnosis. Besides G. vaginalis, Mobiluncus spp., Mycoplasma hominis, and certain obligate anaerobes are now acknowledged as participants in bacterial vaginosis. The finding that G. vaginalis, Mobiluncus spp., and M. hominis inhabit the rectum indicates a potential source of autoinfection in addition to sexual transmission. Extravaginal infections with G. vaginalis are increasingly recognized, especially when the toxic anticoagulant polyanetholesulfonate is omitted from blood cultures and when urine cultures are incubated anaerobically for 48 h. The finding that mares harbor G. vaginalis suggests that an equine model can be developed for studies of Gardnerella pathogenesis.

Subclinical amnionitis in patients with intact membranes in preterm labour

Preterm delivery is the major obstetric and paediatric problem, being responsible for much perinatal morbidity and mortality. Subclinical amnionitis may cause preterm labour and delivery. The rate of subclinical bacterial infection of amniotic fluid was studied in 25 afebrile pregnant women with intact membranes in preterm labour. Specimens of amniotic fluid were collected by transabdominal amniocentesis. Serum and amniotic fluid lactic dehydrogenase (LDH) levels were assessed to determine their usefulness in making the diagnosis of subclinical amnionitis. Aerobic bacteria were isolated from 48% (12/25) of the specimens. Thus, subclinical amnionitis may play a substantial role in patients with intact membranes in preterm labour. However, transabdominal amniocentesis is not routinely indicated in similar asymptomatic patients because microbiological and especially LDH studies require further evaluation.

Group B streptococci in the lower urogenital tract and late abortions

The occurrence of group B streptococci in the lower urogenital tract of 150 women with signs of abortion and 100 women with uncomplicated pregnancy was studied. Group B streptococci appeared significantly more frequently in the urine (p less than 0.001) and in the uterine cervix (p less than 0.01) of women with abortion. Delivery resulted in 85% of patients with group B streptococci in the urine and in 42% of patients with no group B streptococci (p less than 0.001). Group B streptococci were cultured from amniotic fluid from three of eight women with intact membranes and were isolated from the urine and cervix. These bacteria were antibody coated as demonstrated by an immunofluorescence technique. Group B streptococci were recovered from blood or liver in six fetuses, including two who had group B streptococci in the amniotic fluid. The study demonstrates an association between the occurrence of group B streptococci in the urine and cervix and late abortions.