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The clinical manifestations of Neisseria meningitidis can range from transient fever and bacteremia to fulminant disease with death ensuing within hours of the onset of clinical symptoms. It is a common cause of community-acquired bacterial meningitis in both children and adults. Mortality can be veRead more
The clinical manifestations of Neisseria meningitidis can range from transient fever and bacteremia to fulminant disease with death ensuing within hours of the onset of clinical symptoms. It is a common cause of community-acquired bacterial meningitis in both children and adults. Mortality can be very high in patients with meningococcal disease if the infection is not treated appropriately, and long-term sequelae can be severe even in successfully managed cases due primarily to difficulty in managing the endotoxin-induced vascular collapse frequently induced by this organism. The symptoms of Neisseria meningitidis can vary from mild to severe and can include:
– Sudden onset of fever
– Headache
– Stiff neck
– Nausea and vomiting
– Photophobia (sensitivity to light)
– Altered mental status (confusion)
– Skin rash
– Seizures
1. Gram Stain: In a Gram-stained smear of centrifuged deposit of specimen (CSF or sterile body fluid), N. meningitidis appear as Gram-negative, coffee-bean-shaped diplococci occurring intracellularly or extracellularly in PMN leukocytes. 2. Culture: Isolation of N. meningitidis (from blood, CSF, orRead more
1. Gram Stain: In a Gram-stained smear of centrifuged deposit of specimen (CSF or sterile body fluid), N. meningitidis appear as Gram-negative, coffee-bean-shaped diplococci occurring intracellularly or extracellularly in PMN leukocytes.
2. Culture: Isolation of N. meningitidis (from blood, CSF, or other normally sterile sites) remains the gold standard as it also provides isolates for strain differentiation and susceptibility testing.
Since meningococci are fastidious, samples from sterile body sites are inoculated on either blood or chocolate agar. The chocolate agar base can be enriched with antibiotics such as vancomycin, colistin, nystatin, and trimethoprim for selective isolation of N. meningitidis. For culture from non-sterile sites such as the nasopharynx, a selective media such as Modified New York City or Modified Thayer Martin medium is required. Culture plates should be incubated for a minimum of 48 hours with a source of 5% CO2. On Blood agar, young colonies of N. meningitidis are round, smooth, moist, glistening, and convex, with a clearly defined edge whereas actively growing colonies are grey and unpigmented. Older cultures (> 24 hours) become more opaquely grey and sometimes cause the underlying agar to turn dark.
3. Serological tests: Several serological tests, such as enzyme immunoassay, latex agglutination, and rapid diagnostic tests, are available to detect antibodies against capsular antigens of Neisseria meningitidis. Serological tests help in the retrospective diagnosis of disease. Antibodies are also seen when vaccination is successful and in cases of chronic meningococcemia.
4. Molecular diagnosis: PCR-based diagnosis provides confirmation of meningococcal disease from blood, CSF, or other normally sterile sites with a validity comparable to that of culture-based diagnosis.
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