Sketchy Microbiology: Neisseria Meningitides

"A shocking Death on Campus" — Neisseria Meningitides

College Dorm — N. Meningitides easily spreads in closed quarters like military camp or college dorms via respiratory droplets

Hint: Overall Color

Red Hue – Gram Negative Cocci

Detective MAC – Common Features of Neisseria species

• Gram Negative Cocci

• Diplococci

• Grows on Chocolate Agar, VPN, Enriched Agar

• C5 - C9 MAC Deficiency

• IgA Protease

• Pilli = Antigen Variation

Bottle of MALT Liquor — Only N.

Meningitides ferments maltose

(also glucose, but Maltose Fermentation differentiates it from N. Gonorrhea)

Long Nasopharyngeal Swab — N. Meningidites is found in nasal cavities first, and transmitted via respiratory secretions (droplets, drinks, kissing, coughing, etc.)

Hint: Covered Up

Covered up syringes — N. Meningidites has a polysaccharide capsule

(Capsule is the major virulence factor because it inhibits phagocytosis)

Hint: Why doesn’t B have a syringe

Syringes on the floor - We have a vaccines for N. Meningitides

• The vaccine for Strain A,C,D: includes the polysaccharide capsules

• Vaccine for Strain B: does NOT include the polysaccharide capsule

B doesn’t have a syringe — Strain B is NOT included in the vaccine

(Therefore the most common strain causing Meningitides in developed countries)

Sickle and Hammer Flag — Sickle cell disease patients are more susceptible to N. Meningitides because it is encapsulated

(Sickle Cell Disease [Auto-Splenectomy] or those without a spleen have a higher risk of infection because the spleen is responsible for the removal of encapsulated organisms)

Burning Envelopes – N. Meningitides colonizes the Nasopharynx and then spreads hemotogenously (via blood) → leading to a massive Immune response generated by LOS (lipooligiosaccharides) proteins. These “envelope proteins” are Neisseria’s version of LPS (lipopolysaccharides). Neisseria grows so much of it, that it outgrows the surface area of the bacteria and begins blebbing off. These blebs of LOS envelopes → lead to a massive inflammatory response

Leaky Sprinklers — Leakage of interstitial fluid from capillaries (as a result of the inflammatory response) → hypovolemia

Dark Spots on Carpet — Characteristic petechial rash → thrombocytopenia → DIC (Disseminated Intravascular Coagulation)

Red spot on boxers — Petechial Rash

Shock coming from electrical outlet — Capillary leakage can lead to shock

(The leaky sprinkler [capillary leakage] got into the socket and “shocked” the victim)

Waterhouse — If a patient becomes hypovolemic, peripheral vasoconstriction will go to the max. in an attempt to maintain blood pressure.

As a result, the Adrenal glands can become hypo-perfused → Adrenal infarct → adrenal insufficiency → also contributes to shock

Destruction of Adrenals = Waterhouse Friderichsen Syndrome

What is the entire Pathogenesis of N. Meningitides?

1. Capsulated N. Meningitides is transmitted via resp. droplets

2. The LOS Envelope Proteins bleb off → cause massive inflammatory response

3. The Inflammatory Response → leakage of capillaries + consumption of platelets, → petechial rash

4. The Capillary Leakage → Hypovolemia or Shock (which can also lead to perfused adrenals → Waterhouse Friderichsen Syndrome

5. Development of Waterhouse Friderichsen Syndrome worsens the hypovolemia → worsens shock

What is the Mortality Rate of patients with Meningococcal Meningitis?

15% mortality rate even with Antibiotics

Firefighter’s 3 Axes — Ceftriaxone; 3rd generation Cephalosporin Antibiotic

(Cef-TRI-AX-one)

Important!! Ceftriaxone can penetrate the Blood Brain Barrier

Police w/ Rifampin Rifle - Close contacts (spent 8+ hours with the infected in the last 7 days before onset) will need prophylaxis; Rifampin (Nucleic Acid Inhibitor; Inhibitor of bacterial RNA Polymerase)