Gram-

Capsulated

Coccobacillus

Special medium: Bordet-Gengou medium

Does not grow on cotton; requires calcium alginate swab.

1. Filamentous hemaggultinin (FHA)

-- A surface protein that binds to ciliated cells on respiratory epithelium (specifically, binds to galactose on sulfated glycolipids)

Note: Pertactin and pili/fimbriae also involved in binding

2. Pertussis toxins

-- AB₅ toxin (B binds to cell and allows A to pass in): A subunit ADP-riboxylates Gi protein -> cAMP -> abnormal cellular signaling, increased sensitivity to histamine (vasopermeability, lymphocytes in blood)

-- Calmodulin-dependent adenylate cyclase: leads to high cAMP levels that weaken PMNs (impaired chemotaxis, phagocytosis, and superoxide production)

Note: Calmodulin is specific to host; good strategy.

Note: Pertussis toxins delivered to target cells by type IV secretion

3. Tracheal Cytotoxin (TCT): Paralyzes cilia, crippling the muco-ciliary elevator. Ciliated cells are eventually extruded from respiatory lining. TCT comprises fragments of the bacterial peptidoglycan cell wall, which are released during remodeling/division. 

Note: Damaged ciliated cells eventually extruded from respiratory lining, hence TCT is responsible for long-term "whooping" cough after infection clears. Cell extrusion mediated by IL-1.

Note: Virulence factors (Fha, pertussis toxins, pertactin, pili) are components of acellular vaccine, DTaP)

Penicillin. I don't know why this is special given that it is Gram-.

Human respiratory tract.

Two-component regulatory system: Bvg-S and Bvg-A

1. Sensor protein Bvg-S in cytoplasmic membrane sense environmental cue and autophosphorylates.

2. Phosphate is transferred to a response regulator protein (activator protein), Bvg-A.

3. Bvg-A activates/repressed transcription, allowing for phenotypic switching/ reciprocal expression (no need to express flagella and adhesins at the same time).

Note: Tandem phospho-relay system (repeat phosphorylations) can yield rheostat control instead of simple on/off switch.

Note: Many microbes exploit these phospho-relays to regulate gene expression in response to local cues.

AB₅

-- Pertussis toxin

-- Cholera toxin

-- E. Coli LT

A(-s-s-)B:

-- Diphtheria

-- Tetanus

-- P. aeruginosa exotoxin A

Two phases: Catarrhal and Paroxysmal

Catarrhal Phase (1-2 weeks)

-- Inflammation of mucous membranes, bacterial colonization, worsening cough, fever

-- Highly contagious during this phase

Paroxysmal phase (1-2 months)

-- Severe, persistent cough (whooping in children)

Note: Bacterial infection is cleared at this point. Coughing is due to damaged mucociliary elevator, courtesy of TCT.

During catarrhal phase we can treat with erythromycin, though host response can clear infection without treatment. During paroxysmal phase, infection has already cleared - whooping will persist.

Note: Vaccination is key!