1. Meningitis is an infection of meninges, the membrane that protects the brain. To prove there is an infection in the brain, you can take a specimen of cerebrospinal fluid by lumbar puncture. The sample can be examined microscopically (for the presence of bacteria and leukocyte) or chemically(by looking at the protein count).
2. Cerebrospinal fluid should be sterile so the presence of eukaryotic cells means that the patient is meninges infected by bacteria. The diagnosis probably is meningitis bacteria. The capsule indicates the bacteria is Neisseria meningitidis, make the diagnosis become meningococcal meningitis.
Meningitis could also caused by Listeria monocytogenes, Haemophilus influenza, Streptococcus pneumoniae, or a virus.
3. The site of infection of meningitis could be from blood or direct contact to the cerebrospinal fluid.
Direct contact needs an open wound from the skull or the vertebrae that allow the invasion. Any accident that has enough force to fracture the skull be at risk.
Bacteria can spread from blood in case of sepsis. Immunocompromised patient has a higher risk. Children, incomplete vaccination and living in high-density community also increase the risk.