Bacterial meningitis is caused by one of three types of bacteria: Neisseria meningitis, Haemophilus influenzae or Streptococcus pneumoniae. The Centers for Disease Control and Prevention reports that while Haemophilus influenzae used to cause the most cases of bacterial meningitis, vaccine therapy has rendered that strain less effective. Streptococcal---also called pneumococcal---meningitis, now causes the most cases, in addition to Neisseria strains, notes the CDC.
Indirect Cause
One way meningitis can result in adults is when the Streptococcus bacteria enters the bloodstream. Once in the bloodstream, the bacteria can move wherever blood flows. According to the Mayo Clinic, if bacteria gets into the blood flow of the brain or spinal cord, it can inflame the meninges, which is a membranous tissue that wraps around parts of the central nervous system. Under normal conditions, blood that circulates in the body is blocked from circulating in the brain by a system known as the blood-brain barrier. When the meninges are inflamed, the blood infected with Streptococcus bacteria may be allowed entry into the brain, resulting in pneumococcal meningitis.
Direct Cause
Meningitis from the Streptococcus bacteria can also be caused directly through an infection near the brain. Children with a serious ear or sinus infection could end up with meningitis after the infection spreads from the ear or nasal passage into the tissue surrounding the brain. In extremely severe cases, the eardrum may rupture, causing blood to flow from the ear, notes Merck. This increases the chances of the infection spreading into the meninges and causing inflammation.
Treatment
Pneumococcal meningitis is painful to diagnose for the patient. Due to the effect on the central nervous system, diagnosis requires a spinal tap, and withdrawal of cerebral spinal fluid. According to the Meningitis Foundation of America, cerebral spinal fluid will be tested for excessive white blood cell presence, low levels of glucose or increased protein. The importance of the discovery of the exact type of bacteria causing the meningitis can not be understated. Pneumococcal meningitis caused by Streptococcus pneumoniae bacteria is more effectively treated with different antibiotics than an infection caused by the Neisseria meningitis bacteria. Treatment typically includes intravenous and oral antibiotics to control or stop the growth of the invading bacteria.
