Meningitis is an infection of the meninges and fluid surrounding the brain and spinal cord. Neisseria meningitidis is one of the leading causes of bacterial meningitis (1). Neisseria meningitidis is a gram-negative aerobic diplococcus. Marchiafava and Celli were the first to report Gram-negative diplococci in cerebrospinal fluid in a fatal case of meningitis in 1884. Weichselbaum isolated the bacterium in 1887 and established the isolates as a specific species and the proven cause of meningitis (4)
These bacteria have a characteristic coffee bean shape when observed under a microscop! e. The inside of the bacteria is encompassed by a cell envelope consisting of three layers, an inner layer called the cell membrane, a middle layer made up of peptidoglycans, and an outer layer called the cell wall. The cell wall consists of lipopolysaccharides and outer membrane proteins, which are linked together, giving the bacterium its shape (3). This bacterium undergoes autolysis during growth and releases part of its cell wall in a soluble form. The major toxin of N. meningitidis is its lipooligosaccharide, LOS, and its mechanism is endotoxic.