Final answer:
Neisseria meningitidis is a member of the normal respiratory microbiota and can cause infections in other areas of the body, including the brain. It is transmitted through respiratory secretions.
Step-by-step explanation:
N. meningitidis is found in the normal respiratory microbiota in 10%-20% of the human population. In most cases, it does not cause disease, but for reasons not fully understood, the bacterium can sometimes invade the bloodstream and cause infections in other areas of the body, including the brain. The disease is more common in infants and children, like Hannah.
Many of the bacteria that can cause meningitis are commonly found in healthy people. The most common causes of non-neonatal bacterial meningitis are Neisseria meningitidis, Streptococcus pneumoniae, and Hemophilic influenzae. All three of these bacterial pathogens are spread from person to person by respiratory secretions. Once in the blood, these pathogens can disseminate throughout the body and are capable of both establishing an infection and triggering inflammation in any body site, including the meninges.
N. meningitidis has a high affinity for mucosal membranes in the oropharynx and nasopharynx. Contact with respiratory secretions containing N. meningitidis is an effective mode of transmission.