Neisseria meningitidis -- Meningitis: Difference between revisions

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==Pathogenesis==
==Pathogenesis==
===Transmission===
Meningococci have been categorized into 13 serogroups: A, B, C, D, 29E, H, I, K, L, W-135, X,Y, and Z. Of the 13 serogroups, A, B, C, W135, and Y remain encapsulated, causing more than 90% of the invasive disease across the world. (carriage state) <i>N. meningitidis</i> commonly colonizes in the nasopharynx. As a result, droplets or discharge from the nose or throat that contain <i>N. meningitidis</i> can be transferred to other individuals, resulting in successful transmission of the species. Direct contact with the respiratory droplets can occur through coughing, sneezing, and kissing. (mening 1? CHECK CITATION) Transmission also occurs at higher frequencies in environments where crowding is common, such as prisons, dormitories, and military installations. (PHC mening)
===Infectious dose, incubation, and colonization===
The infectious dose of <i>N. meningitidis</i> is unknown, but the transmission of bacteria is highly contagious. On average, the incubation period is 2-4 days but can range from approximately 2-10 days, while invasive meningococcal infections occur within 14 days of acquiring the bacteria. (Canada) Individuals with <i>N. meningitidis</i> infections are most contagious during the period of 3 days preceding initial symptom presentation and continue to remain infectious while meningococci persists in nasalpharynx discharge. (mening 1) Humans serve as the sole natural reservoir for <i>N. meningitidis</i>, and 10% to 35% of adults and adolescents are asymptomatic carriers, with the majority of bacteria carried as nonpathogenic strains. (mening) (cs118) Carriers of meningococci have the bacteria as a commensal microorganism residing in the respiratory tract and nasopharynx mucosa. It is the penetration of these colonized bacteria into the mucosal membrane and subsequently into the bloodstream that results in various forms of illness. (carriage state)
==Clinical features==
==Clinical features==
==Diagnosis==
==Diagnosis==

Revision as of 10:18, 27 July 2014

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University of Oklahoma Study Abroad Microbiology in Arezzo, Italy[1]
Scanning electron microscope image of Neisseria meningitidis. From: Bioquell.com [2]

Etiology/Bacteriology

Taxonomy

| Domain = Prokaryote | Phylum = Proteobacteria | Class = Betaproteobacteria | Order = Neisseriales | Family = Neisseriaceae | Genus = Neisseria | species = Neisseria meningitidis

NCBI: Taxonomy Genome: Genome

Description

Neisseria meningitidis is an aerobic, Gram-negative diplococcus that causes meningococcal diseases such as meningococcemia and bacterial meningitis. Meningitis arises upon inflammation of the meninges, which consists of the membrane that envelops and protects the central nervous system. N. meningitidis is also commonly known as meningococcus and is carried by approximately 8-25% of the general population in the normal mucosa of the nasopharynx and upper respiratory tract. The varying compositions of the polysaccharide capsule on different strains of N. meningitidis allow the species to be divided into several serogroups, with serogroups A, B, and C as the prominent strains responsible for outbreaks of meningitis in both developed and undeveloped countries. The infection is transmitted to individuals through contact with respiratory secretions or saliva from sneezing, coughing, and talking. Early diagnosis and immediate treatment are vital to the survival of patients assumed to be infected with meningococcal meningitis. Symptoms of the disease are sudden onset and include fever, neck stiffness, and severe headache. (Ref. CDC and Bioquell)

Pathogenesis

Transmission

Meningococci have been categorized into 13 serogroups: A, B, C, D, 29E, H, I, K, L, W-135, X,Y, and Z. Of the 13 serogroups, A, B, C, W135, and Y remain encapsulated, causing more than 90% of the invasive disease across the world. (carriage state) N. meningitidis commonly colonizes in the nasopharynx. As a result, droplets or discharge from the nose or throat that contain N. meningitidis can be transferred to other individuals, resulting in successful transmission of the species. Direct contact with the respiratory droplets can occur through coughing, sneezing, and kissing. (mening 1? CHECK CITATION) Transmission also occurs at higher frequencies in environments where crowding is common, such as prisons, dormitories, and military installations. (PHC mening)

Infectious dose, incubation, and colonization

The infectious dose of N. meningitidis is unknown, but the transmission of bacteria is highly contagious. On average, the incubation period is 2-4 days but can range from approximately 2-10 days, while invasive meningococcal infections occur within 14 days of acquiring the bacteria. (Canada) Individuals with N. meningitidis infections are most contagious during the period of 3 days preceding initial symptom presentation and continue to remain infectious while meningococci persists in nasalpharynx discharge. (mening 1) Humans serve as the sole natural reservoir for N. meningitidis, and 10% to 35% of adults and adolescents are asymptomatic carriers, with the majority of bacteria carried as nonpathogenic strains. (mening) (cs118) Carriers of meningococci have the bacteria as a commensal microorganism residing in the respiratory tract and nasopharynx mucosa. It is the penetration of these colonized bacteria into the mucosal membrane and subsequently into the bloodstream that results in various forms of illness. (carriage state)

Clinical features

Diagnosis

Treatment

Prevention

Host Immune Response

References