Streptococcus agalactiae infects glial cells and invades the central nervous system via the olfactory and trigeminal nerves

Anu Chacko, Ali Delbaz, Indra N. Choudhury, Tanja Eindorf, Megha Shah, Christopher Godfrey, Mathew J. Sullivan, James A. St John, Glen C. Ulett, Jenny A. K. Ekberg

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
6 Downloads (Pure)


Streptococcus agalactiae causes neonatal meningitis and can also infect the adult central nervous system (CNS). S. agalactiae can cross the blood-brain barrier but may also reach the CNS via other paths. Several species of bacteria can directly invade the CNS via the olfactory and trigeminal nerves, which extend between the nasal cavity and brain and injury to the nasal epithelium can increase the risk/severity of infection. Preterm birth is associated with increased risk of S. agalactiae infection and with nasogastric tube feeding. The tubes, also used in adults, can cause nasal injuries and may be contaminated with bacteria, including S. agalactiae. We here investigated whether S. agalactiae could invade the CNS after intranasal inoculation in mice. S. agalactiae rapidly infected the olfactory nerve and brain. Methimazole-mediated model of nasal epithelial injury led to increased bacterial load in these tissues, as well as trigeminal nerve infection. S. agalactiae infected and survived intracellularly in cultured olfactory/trigeminal nerve- and brain-derived glia, resulting in cytokine production, with some differences between glial types. Furthermore, a non-capsulated S. agalactiae was used to understand the role of capsule on glial cells interaction. Interestingly, we found that the S. agalactiae capsule significantly altered cytokine and chemokine responses and affected intracellular survival in trigeminal glia. In summary, this study shows that S. agalactiae can infect the CNS via the nose-to-brain path with increased load after epithelial injury, and that the bacteria can survive in glia.

Original languageEnglish
Article number793416
JournalFrontiers in Cellular and Infection Microbiology
Publication statusPublished - 24 Feb 2022
Externally publishedYes


  • astrocyte
  • bacteria
  • central nervous system
  • olfactory ensheathing cell
  • peripheral nerve
  • Schwann cell
  • Streptococcus agalactiae

Cite this