How to prevent meningitis in infants? We know more

French researchers* have for the first time succeeded in explaining the predisposition of newborns to group B Streptococcus meningitis. Their work is published in the journal Journal of Clinical Investigation.

Each year throughout the world, thousands of infants are affected by group B streptococcal meningitis, which generally spares adults. Often fatal, the disease can also cause severe sequelae in surviving babies.

“A major public health problem”

Group B streptococci are present in the vaginal microbiota of 20 to 30% of women. To avoid infection of the newborn at the time of birth, which could lead to sepsis and, in the most serious cases, meningitis, many developed countries, including France, have implemented vaginal screening a few weeks before delivery. Women with group B streptococci receive antibiotics at the time of delivery.

This strategy greatly reduced the incidence of group B streptococcal infections occurring during the first week of life, but had no effect on those occurring between 1 week and 3 months of life. In addition, in many countries around the world, no prenatal screening is offered, and many babies die after birth from group B streptococcal meningitis. “It is therefore a major public health problem”, say the researchers.

Predisposition of infants

To better understand the disease and improve care for mothers and children, Inserm scientist Julie Guignot and her team sought to understand what predisposes infants to this disease, whereas children and adults are not only exceptionally affected by this type of meningitis.

In previous work, scientists had shown that a variant of group B streptococcus was responsible for more than 80% of cases of meningitis in newborns. This variant expresses specific proteins on its surface, which play an essential role in crossing the blood-brain barrier separating the blood from the brain.

Using complementary approaches, the researchers have demonstrated that one of the proteins exclusively expressed by this variant specifically recognizes two receptors present in cerebral blood vessels which constitute the main element of the blood-brain barrier. Using human samples, they demonstrated that these receptors are overexpressed in newborns. These brain receptors are however not present in adults, which explains why group B streptococcus is only very rarely responsible for meningitis beyond the first year of life, as the bacteria cannot reach the brain.

Interesting therapeutic avenues

Using animal models of meningitis, the researchers confirmed their results, showing that the expression of these receptors during the postnatal period contributes to the susceptibility of the newborn to meningitis due to variant group B streptococcus.

For researchers, these results open up interesting therapeutic avenues. “The idea would be to develop treatments that target these receptors at the level of the blood-brain barrier. In the longer term, we would like to study the individual susceptibility factors leading to the development of these infections. infants at risk born to mothers colonized with this variant”, concludes Julie Guignot.

*From Inserm, Collège de France, CNRS, Institut Pasteur, University of Paris and AP-HP.