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Chapter 22 Lecture 2 (Diphtheria (Pathogenesis and epidemiology (Spread…

- - - - Ubiquitous in animals and humans colonizing the skin and the respiratory, GI, urinary, and genital tracts
    - - C. diptheriae produces diphtheria toxin which are directly related to the signs and symptoms of diphtheria
        
        Prevents polypeptide synthesis and causes cell death which is why one of the most potent toxins
- - - - Pharyngitis
        
        Sore throat and difficulty swallowing, swollen lymph nodes and purulent abscesses covering the tonsils
      - Often accompanied by fever, malaise, headache, pain during swallowing, bad breath
      - Laryngitis and bronchitis can occur if the infection spreads to lower respiratory tract
      - Complications including scarlet fever, after one to two days of pharyngitis, the streptococci releases toxins, trigger a fever, and a rash that begins on the chest and spreads across the body. Tongue becomes strawberry red. Rash disappears after a week and skin will slough off like SSSS
      - rheumatic fever,( inflammation can lead to damage heart valves and muscle) and acute glomerulonephritis(disease of the kidney) occur in some cases
    - - Major cause of bacterial pharyngitis, and scarlet and rheumatic fevers are from the group A streptococci (S. pyogenes)
      - They have a number of structures, enzymes and toxins that allow them to survive as pathogens in the body:
        
        M proteins cause inhibition of complement component C3b
        
        Hyaluronic acid capsule –may camouflage the bacterium from phagocytosis
        
        Streptokinases- are enzymes that break down blood clots , that will enable group A streptococci to spread rapidly through damaged tissues
        
        C5a peptidase – an enzyme that breaks down complement protein C5a ultimately decreases the movement of leukocytes into the site of infection
        
        Pyrogenic toxins - stimulate leukocytes to release cytokines that in turn stimulate fever, rash , and shock
        
        Streptolysins- lyse erythrocytes, leukocytes and platelets