A placental view of the diagnosis and pathogenesis of congenital listeriosis

Intracellular Organisms as Placental Invaders

In this article we present a novel model for how the human placenta might get infected via the hematogenous route. We present a list of diverse placental pathogens, like Listeria monocytogenes or Cytomegalovirus, which are familiar to most obstetricians, but others, like Salmonella typhi, have only been reported in case studies or small case series. Remarkably, all of these organisms on this list are either obligate or facultative intracellular organisms. These pathogens are able to enter and survive inside host immune cells for at least a portion of their life cycle. We suggest that many blood-borne pathogens might arrive at the placenta via transportation inside of maternal leukocytes that enter the decidua in early pregnancy. We discuss mechanisms by which extravillous trophoblasts could get infected in the decidua and spread infection to other layers in the placenta. We hope to raise awareness among OB/GYN clinicians that organisms not typically associated with the TORCH list might cause placental infections and pregnancy complications.

Listeriosis of the placenta: clinicopathologic study of seven cases

OBJECTIVE

The purpose of our study was to evaluate the usefulness of placental examination in the diagnosis of prenatal listeriosis.

STUDY DESIGN

Over a 7-year period, 4597 placentas with clinical indications for examination were retrospectively studied for morphologic evidence of listeriosis. The microbiology laboratory file records of positive Listeria monocytogenes cultures were used to confirm the diagnosis. The clinical records were studied for manifestations of the infection both in the neonates and in the mothers.

RESULTS

Seven placentas were identified as having listeriosis. The presence of macroabscesses, as opposed to microabscesses, was the most characteristic finding in this study, and the silver impregnation method was more reliable in identification of the bacilli in the tissue sections than the tissue Gram stains.

CONCLUSIONS

Listeriosis could be diagnosed by placental examination alone, and this examination frequently strengthened the clinical diagnosis. When the infection was not suspected clinically, the examination helped us reach the correct diagnosis.

A 10-year prospective study of women with a history of recurrent fetal losses fails to identify Listeria monocytogenes in the genital tract

An attempt was made to isolate L. monocytogenes from the cervix and endometrium of patients who presented to the Dartmouth-Hitchcock Medical Center's Reproductive Counseling Unit with a history of two or more fetal losses. Endometrial tissue and endocervical swabs were cultured in a prospective fashion for the presence of L. monocytogenes. During the 10-year study period, none of the patients with recurrent fetal losses were found to harbor the organism in their genital tract. It would appear that L. monocytogenes contributes to fetal loss, but probably not on a recurrent basis. Routine culturing for L. monocytogenes in the asymptomatic patient in a clinical setting is not cost-effective and is therefore unwarranted. The portal of entry is possibly the GI tract, with bacteremia and transplacental spread to the fetus. Ascending infection through the introduction of L. monocytogenes into the vagina and cervix may occur. Because of the difficulty in identifying L. monocytogenes in the feces, as well as the self-limiting nature of listeriosis, it would appear unwarranted to give routine administration of antibiotics in patients who have had a history of a fetal loss because of L. monocytogenes.

The role of chronic non-specific inflammatory lesions of the placenta in intra-uterine growth retardation

Placentae from 108 cases of intra-uterine growth retardation (IUGR) were examined microscopically with special emphasis on the occurrence of chronic non-specific inflammatory lesions. Sixteen cases (14.8%) showed severe villitis (SV) while 15 (13.8%) showed moderate villitis (MV). The SV-cases seemed to be more severely growth retarded, while no differences in the growth patterns appeared. A greater part of the SV-cases than of those with moderate or no villitis were cases without maternal or fetal causes for the growth retardation. The placental weight and placental index were higher in the cases with severe villitis. A mixture of lymphocytes and histiocytes was the most common finding among the placentae with villitis. Six cases of umbilical cord thrombangitis were registered, the majority of these being associated with villitis. The present findings suggest an association between intrauterine growth retardation and villitis of unknown etiology.

Perinatal listeriosis--a review of twelve patients

From July, 1974 to February, 1978, we managed 12 infants with listeriosis. This infection presented in two distinct forms: an early-onset type (nine patients), often representing a congenital infection following maternal illness, and a late-onset type in which the patient presented with meningitis (three patients). Of our nine infants with early-onset disease, three died, three developed permanent sequelae, and only three were normal at follow-up. Appropriate early management in the perinatal period may improve the outlook in this condition. Affected infants were often premature and had pneumonia, rash, and hepatosplenomegaly at birth. Prenatal clues to the diagnosis included maternal fever, abdominal pains, and leukocytosis with meconium staining of the preterm amniotic fluid. Examination of gastric aspirate at birth showed gram-positive coccobacilli. Antibiotic therapy should be started prenatally and continue for three weeks after birth to prevent recurrences of the late-onset type. This late-onset disease presented as meningitis after the second week of life and responded well to antibiotics. Our three patients recovered without sequelae.