Neisseria Meningitidis

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Introduction
Neisseria meningitidis (the meningococcus) is a Gram-negative bacterium which normally resides as a harmless commensal in the human nasopharyngeal mucosa [1] . The encapsulated bacterium is capable of causing serious blood and brain infections, and it is a major cause of epidemic sepsis and meningitis [2]. The bacterium is now classified into 13 serogroups, which are based on the chemical composition of the polysaccharide capsule. Only six serogroups (A, B, C, W, X and Y) are responsible for the life threatening diseases [3]. There is a higher incidence of meningococcal disease in infants and children aged <4 years. The disease can rapidly progress from bacteremia to life-threatening septic shock syndrome or septicaemia [4]. Once the pathogen enters the host, it takes around 1-14 days for the disease to occur [4]. The first step after entering the host is to attach and colonize the mucosal epithelium of the nasopharynx. In most of the cases the meningococcus does not penetrate the mucosal epithelium and the human hosts simply remain carriers, whereas in others, it can cause invasive meningococcal disease [5].
Different virulence factors are responsible for the pathogenesis of meningococcal disease. The bacterium expresses various cell surface and secreted virulence factors which allows it to colonize and infect the host cells. A number of such virulence factors include the autotransporters [3, 6]. Autotransporters which are secreted via type ⋁ secretion system, currently represent the largest protein family in pathogenic Gram-negative bacteria. It has three main subtypes; classical autotransporter system (type ⋁a or AT-1), the two – partner secretion …show more content…

IgA1 protease, MspA, and App have been placed within the S6-peptidase family in the MEROPS database as they share common ancestry and other features like nature, order and relative positions of their catalytic residues

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