Pathogenic Neisseria

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Neisseria meningitides

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DOC = Penicillin G. Dexamethazone can be used to reduce neurological sequelae after meningitis

Gram (-), Diplococci, oxidase positive, infects humans exclusively, airborne droplets transmission

Cause endemic and epidemic meningitis (only cause of this)

Virulence Factors:
1.) Capsular polysaccharide - determines serogroup and blocks phagocytosis. Group B exhibits molecular mimicry and seen as self-antigen (no vaccine to this serogroup)
2.)LOS - Endotoxin similar to LPS responsible for the most damage - leads to shock (cells don't have to lyse to secrete this)
3.)Pili - mediate initial attachment to epithelial cells
4.) Opacity proteins (Opa) - tight adherence to specific tissue after pili attachment. Can induce cell to internalize bacteria
5.)OMPs - Porins such as PorB that can activate apoptosis via Ca2+ influx
6.) fH binding protein - blocks complement
7.) IgA1 protease - cleaves IgA
8.) Receptors that help steal iron from the host

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Differences b/w Neisseria meningitidis and Neisseria gonorrhoeae

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Gonorrhoeae metabolize Glucose only.
Meningitidis metabolize Maltose and Glucose

Meningitidis has a capsule that prevents dessication. Gonorrhoeae does not have a capsule so needs to be transmitted by intimate contact

Meningitidis is carried as a commensal organism. Gonorrhoeae is not and is always pathogenic

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Bacteria that commonly cause Meningitis

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Neisseria meningitidis (infants & young adults)

Streptococcus pneumoniae (infants and elderly)

Streptococcus agalactiae (neonates)

Haemophilus influenzae (children)

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Seroroups of N. meningitidis that are associated with specific diseases (A, B&C, Y)

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Group A - Epidemic meningitis

Groups B&C - Endemic meningitis

Group Y – pneumonia

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Local Neisseria meningitidis infections

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All have purulent discharge

1.) Pharyngitis
2.) Pneumonia (Serogroup Y)
3.) Urethritis (purulent discharge after oral sex)

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Systemic Neisseria meningitidis infections

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After getting into bloodstream through very vascularized nasopharynx

1.) Meningitis
2.) Meningococcemia - sudden onset, rapid course, worst prognosis. Can lead to adrenal insufficiency with ultimate bilateral destruction of adrenal glands (Waterhouse-Friderichsen syndrome)

Both can lead to neurological sequelae (deafness, retardation, etc.)

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Recurrent meningococcal infections may be caused by:

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Complement deficiency

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Selective Media used to isolate either Neisseria meningitidis or Neisseria gonorrhoeae

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Modified Thayer-Martin agar or New York City agar

contain antibiotics that kill off most commensals. Must use this if specimens collected from a complicated niche (not from CSF, blood)