Essentially, enriched blood agar. Blood agar has been slowly heated to lyse some cells, releasing growth factors including heme and NAD.

Note: Thayer-Martin VCN media is chocolate agar with competing antibiotics to kill off everything but Neisseria.

Paper pH test that looks for cytochrome c oxidases, indicating oxidative phosphorylation for energy production. Positive test turns blue/black when bacterial colony is spread on paper.

Note: Useful for distinguishing Neisseria from other Gram- organisms; Neisseria is oxidase+.

Gram- coccobacilli.

Requires chocolate agar, grows gray smooth colonies. 

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Adherence:

-- Pili

Immune Evasion:

-- Capsule (on virulent serotypes): made of polyribitol phosphate (PRP)

Note: Non-encapsulated ("non-typeable") isolates responsible for >90% of localized disease (e.g. otitis media, sinusitis, bronchitis), but capsulated species cause >90% of invasive disease (e.g. meningitis). Of those, 9 serotypes account for 80% of invasive disease worldwide.

-- IgA protease: cleaves IgA on respiratory mucosa

Note: Convergent evolution with Pneumococcus, Meningococcus, which also cleave IgA

Damaging:

-- Endotoxin (LPS): stimulates innate immune response (cytokine storm)

Targets capsular antigens (particularly polyribitol phosphate, PRP). PRP conjugate vaccine available, successful.

Note: While capsule initially helps bacteria evade host immune response, capsular polysaccharides are prime target for antibodies once humoral immunity kicks in.

Note: Capsules are typed a, b, c, d, e, f. Hib is most virulent.

Based on their capsule, so only capsulated isolates are typeable. 6 types are names a, b, c, d, e, f.

Note: Type b is the most virulent, hence the Hib vaccine.

Note: Noncapsulated (non-typeable) isolates cause >90% of local, non-invasive infections such as otitis media or bronchial infection. COPD patients get recurrent non-typeable H. influenzae infections. Capsulated isolates are responsible for invasive disease, e.g. meningitis.

Young children haven't yet developed mechanism T-cell independent antibody response to polysaccharides. Newborns have conferred immunity from mother's antibodies.

An elevated number of copies of gene coding for capsule is associated with decreased efficacy of vaccine. 

Note: Just emphasizes importance of capsule!

Gram-, kidney bean-shaped pilated diplococci. Grows on Thayer-Martin VCN media (chocolate agar + selective antibiotics to eliminate competition) in small, bluish-gray colonies.

Note: Lots of Gram- rods cause infection, but Neisseria is the main disease-causing Gram- coccus.

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Grows on Thayer-Martin VCN media, ferments maltose and glucose and is oxidase positive. (So are other Gram- bacteria like P. aeruginosa, so I'm not sure why Swanson made a point of this.)

Adherence:

-- Pili: can have phosphorylcholine on surface; mimics phosphatidylcholine, allows stealth adhesion to respiratory mucosa.

Note: C-reactive protein targets phosphorylcholine in bloodstream; inborn error-prone polyG mechanism allows phase-variation of expression, survival a subset of organisms in blood.

--Opc, Opa: outer membrane proteins important for adherence and invasion

Note: Phase-variation of surface proteins important to virulence

Immune Evasion:

-- Capsule

-- IgA1 protease

Damage:

-- Endotoxin (LPS): N. meningitis exhibits copious blebbing/shedding of cell wall, releasing endotoxin which induces cytokines TNFa, IL-1.

Note: Can causes blood vessel damage/hemorrhage, which presents as petichiae. 

-- Hemolysin

Immune evasion technique that involves stochastic switching of antigenic phenotype, e.g. LPS phenotype. This confers heterogeneity to a bacterial population, and increases the chance that at least some will survive under varying circumstances

Note: E.g. Expression of phosphoryl choline on N. meningococcus is beneficial during adherence to respiratory mucosa, but is a target of C-reactive protein in the blood. If some organisms switch of phosphoryl choline expression after invasion, they will survive in blood.

It mimics phosphatidylcholine, commonly found on mucosal host cells, so it helps menigococcus evade immune response and adhere. 

Note: After invasion into the bloodstream, phosphorylcholine becomes a liability (target of CRP); phase-variation allows differential expression so some bacteria survive.

A protein (non-antibody B globulin, restricted to serum) that is upregulated during acute-phase inflammation that opsonizes cells expressing phosphatidylcholine and activates complement. The idea is that it binds components of microbes and damaged tissues (that shouldn't be in blood compartment).

When meningococcus invades the bloodstream, organisms decorated with phosphorylcholine (which mimics host phosphatidylcholine) are targeted.

Slipped strand mispairing generates variants at high frequency.

Note: Phosphorylcholine expression depends on number of polyG repeats; if 8 or 11, expressed (note - one codon difference; frameshift negligible); 9 or 10 not expressed. Same idea with Opa, but repeats are CTCTT.

Young children (don't have T cell-independent response to capsule), but not newborns (who have mother's residual antibodies).

Army recruits, college students, others who come from different geographical locales (immunity to local variants, but maybe not others) and live in close quarters.

Includes capsular antigens from various serotypes (A, C, W135, Y), which induce T cell-independent antibody response. 

-- Does not protect young children; we have no conjugated vaccine for meningococcus

-- Does not contain type B antigen, which is a polymer of sialic acid, and mimics host cell structures. Thus, B antigen does not elicit immune response.

We have no conjugated vaccine, so it will not be useful in young children. Military recruits and college students receive meningococcal vaccine.

Nasopharynx. Part of normal flora. Transmitted by respiratory droplets.

Upper respiratory tract; 5-10% of people are carriers.

Transmitted by respiratory droplets.

Its primary capsular antigen is a homopolymer of sialic acid, which is present on host cells and thus a poor immunogen.

Soil, water, GI tracts of animals. NOT part of human flora.

Note: Very hardy; can survive pasteurization and grow at 4^oC (refrigerator); found in meats, cheeses

Eating meats, cheeses, other dairy products housing the bacteria.

Note: Really only affects immunocompromised.

Once infected, the entire life cycle of Listeria is intracellular (even transmission to other cells is through protective host-membrane sheath); bacteria are protected from serum, so antibodies don't have access.

1. Internalin induces entry into host cells

2. Hemolysin, aka Listeriolysin O (LLO): pore-forming toxin for escape from phagolysosome.

3. ActA: Recruits host actin for motility (ActA induced actin nucleation behind bacteria)

4. Forms protrusion, which is surrounded and phagocytozed by neighboring cell (protrusion covered by PM, so Listeria never exposed to serum/ immune system)

5. LLO and phospholipase C allow escape from phagolysozome in new host cell.

Note: Once inside a cell, Listeria is an intracellular pathogen and will not see the outside again.

Actin-based motily; host actin is recruiting. "Comet-tail" is not moving; rather, Brownian motion causes slight movements, and ActA induces polymerization behind bacteria so it can't slip back, propelling it forward.

Note: Remember, the advantage is evasion of innate immune system; Listeria requires full T-cell function. 

Those lacking a full T-cell response (immunocompromised, pregnant, neonates). Cell-mediated immunity is required to activate macrophages to destroy Listeria (before it becomes intracellular?)