Streptococcal meningitis: we know why infants are 30 times more affected

Every year throughout the world, thousands of infants are affected by group B streptococcal meningitis. Often fatal, the disease can also cause serious sequelae in babies who survive, while children and adults seem to be spared this disease. type of meningitis. The Inserm researchers, accompanied by other researchers from the Collège de France, the CNRS, the Institut Pasteur, the University of Paris and the AP-HP wanted to understand what predisposed infants to meningitis to streptococcus. They have just published the results of their research in the journal Cell reports.

The bacterium colonizes the intestine of the newborn

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. In this study, they found that immaturity of the newborn’s gut microbiota is partly responsible for neonatal susceptibility to bacterial meningitis due to group B streptococcus. In the absence of mature microbiota, the bacteria can indeed abundantly colonize the intestine of the newborn. In addition, the barrier function of the blood vessels of the intestine that the bacterium must cross to disseminate to the brain through the blood is reduced and the immune system is unable to control the infection.

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 childbirth. 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. That’s why scientists have sought to understand what predisposes infants to streptococcal meningitis.

Note that in previous works, published in the Journal of clinical investigationInserm researchers had identified and demonstrated that the receptors for a bacterial protein allowing the crossing of the blood-brain barrier were overexpressed in newborns and absent in adults.

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