(I) Gram Negative Cocci - (2) * Neisseria meningitidis Flashcards
Which species of Neisseria ferments maltose?
N. meningitidis
What is the first place N. meningitidis colonizes?
Nasopharynx
Which strain of N. meningitidis most commonly causes meningitis?
Type B
Differentiate between the vaccine for H. influenzae and N. meningitidis in regards to the contained capsular antigens
(1) H. influenzae: ✔ Type B capsular antigen
(2) **N. meningitidis: ✘ Type B capsular antigen **
Name 2 genetic defects which increase your risk for N. meningitidis
(1) C5-9 deficients
(2) **Sickle cell **
What organism has LOS instead of LPS?
N. meningitidis
Describe the pathogenesis of Waterhouse-Friderichsen syndrome
LOS induced inflammation
⇒ ↑ Vascular permeability
⇒ ↑ Exudation
⇒ ↓ Perfusion
⇒ Reflexive vasoconstriction
⇒ Ischemic adrenals
(WFS can occur due to other organisms, and in that case inflammation would not be due to LOS)
What organism is most associated with meningitis with a petechial rash?
N. meningitidis
What is Waterhouse-Friderichsen syndrome?
Sepsis ⇒ Hemorrhage of adrenals
Treatment: N. meningitidis
Ceftriaxone
Prophylaxis: N. meningitidis
Rifampin, ciprofloxacin, ceftriaxone
(For close contacts ≡ Someone who spent ≥ 8 hours with patient in 7 days prior to onset of symptoms)
Diagnosis for N.meningitidis is ALWAYS using
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Diagnosis for N.meningitidis is ALWAYS using
Blood (+ CSF + Throat swab + other sites) cultures (depending on clinical presentation)
Also can do
- direct gram stain of CSF
- Molecular diagnosis becoming increasingly important
Note that the diplococci can be seen (Gram stain) or cultured from biopsies of the petechiae.
How to differentiate N. meningitidis from N. gonorrhoeae?
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How to differentiate N. meningitidis from N. gonorrhoeae?
N.meningitidis is maltose fermenting
Prophylaxis in close contacts of neisseria meningitidis:
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Prophylaxis in close contacts of neisseria meningitidis:
Rifampicin, ciprofloxacin, ceftriaxone
Risk factors of Neisseria meningitidis infection include (IMPT!!!)
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Risk factors of Neisseria meningitidis infection include (IMPT!!!)
- Hajj pilgrimage
- travel to African “meningitis belt”
- asplenia/hyposplenism – recommended for vaccinations/prophylactic antibiotics (same as pneumococcus)
- Army recruits
- College freshmen (freshmeningitis)
Splenectomy predisposes a person to infection by […] bacteria (pneumococcus and meningococcus)
Splenectomy predisposes a person to infection by encapsulated bacteria (pneumococcus and meningococcus)
some H.influenze strand are encapsulated
If u are damn curious why:
“Our immune system clears encapsulated bacteria by opsonizing them with antibodies and then the macrophages and neutrophils in the spleen (the reticulo-endothelial system) phagocytose the opsonized bacteria. So, patients who have lost their spleens (asplenic), either from trauma or from sickle-cell disease, have difficulty clearing encapsulated bacteria and are more susceptible to these infections”
Tell me about meningococcus vaccines (vvvvvvvv IMPT!!!)
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What capsule types are included in the quadrivalent vaccine? (IMPT!)
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Tell me about meningococcus vaccines (vvvvvvvv IMPT!!!)
- Vaccine for N.meningitidis is NOT routine in singapore. Familarize yourself with the National Childhood Immunization Schedule!
- Polysaccharide vaccine NOT effective in infants (same as pneumococcus PPSV23)
- Quadrivalent conjugated vaccines are better. Monovalent vaccines are country specific (C in UK, A in meningitis belt)
What capsule types are included in the quadrivalent vaccine? (IMPT!)
A, C, W135, Y
Group B vaccines are protein based, using combinations of sub-capsular peptides. Its called MenB, but its fairly new and not recommended for routine vaccination.
Treatment of Neisseria Meningitidis? (vvv IMPT!!!)
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Treatment of Neisseria Meningitidis? (vvv IMPT!!!)
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Ceftriaxone (clears throat carriage, covers major pathogens)
AND - Benzylpenicillin (add in case of resistance, also cuz meningitis not small matter)
can be minimalist and use Benzylpenicillin (but does not clear throat carriage)
Tbh the moment u add vanco….the gram positives are all probably all gone case alr.
What is the clinical presentation of Neisseria Meningitidis infection? (vvvvvvvv IMPT!!!)
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What is the clinical presentation of Neisseria Meningitidis infection? (vvvvvvvv IMPT!!!)
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Meningococcaemia (when meningococcus enters blood stream, may progress to severe state of fulminant meningococcaemia, systemic **inflammatory response syndrome SIRS)**
- Non-blanching meningococcal rash (disseminated petechiae –> purpura –> ecchymoses on skin & conjunctiva)
- Haemorrhagic adrenalitis (Waterhouse-Friderichsen syndrome) -
Meningitis
- uncommon presentations: pneumonia, pericarditis, endocarditis, conjuctivitis, arthritis, chronic meningococcaemia (intermittent rash)
- Can develop into fulminant meningococcaemia/meningitis
Non-blanching =blood outside vessels/not hyperraemia = haemorrhagic rash
VERY important card. Meningitis + non blanching rash = N. meningitidis!!
“Meet the 2 pathogenic kidney beans, which have been removed from the microscope slide. They are sitting together at the breakast table. Notice that they sit facing each other, forming a gram-negative dough nut-shaped diplococcus. The bean on the left, Neisseria meningitidis , drinks a pot of cofee and becomes very nervous and irritable (central nervous system irritation-meningitis). The other pathogenic kidney bean is Neisseria gonorrhoeae , who is a pervert (notice how he is displaying the latest center-old pin-up). He enjoys hanging out on sexual organs and swimming in “ sexual fluids.” He causes the sexually transmitted disease (STD) gonorrhea.”
