Corynebacterium diphtheriae
Corynebacterium diphtheriae
Biological Features o Aerobic, Gram*, Noncapsulated, rods ●Gray- black colonies on tellurite亚碲酸盐 medium Metachromatic granules Chinese-letter morphology in Gram stain
Biological Features ⚫ Aerobic, Gram+ , Noncapsulated, rods ⚫ Gray-black colonies on tellurite亚碲酸盐medium ⚫ Metachromatic granules Chinese-letter morphology in Gram stain
Transmission and Risk factors ● solely among humans● Poor nutrition ● spread by droplets o Crowded or unsanitary ● secretions living conditions ● direct contact o Low vaccine coverage among infants and children o Immunity gaps in adults
Transmission and Risk factors ⚫ solely among humans ⚫ spread by droplets ⚫ secretions ⚫ direct contact ⚫ Poor nutrition ⚫ Crowded or unsanitary living conditions ⚫ Low vaccine coverage among infants and children ⚫ Immunity gaps in adults
Pathogenesis of diphtheria 3, Disease Pharyngeal diphtheria 4. Exit oxia-pseudomembrane obstruction Lymphadenitis rarely become Cutaneous diphtheria disseminated but Systemic complications toxin becomes blood borne Toxic myocarditis and congestive heart failure o Early stages: Sore throat. Low fever. Swollen neck glands Late stages: Airway obstruction and breathing difficulty. shock
Pathogenesis of diphtheria ⚫ Early stages: Sore throat. Low fever. Swollen neck glands. ⚫ Late stages:Airway obstruction and breathing difficulty. Shock
Diphtheria Toxin (DT e Cleaved to yield A/B fragment, joined by S-s bond A(catalytic domain) B(transmembrane and receptor binding domains o Receptor: heparin-binding epidermal growth factor -rich on cardiac cells and nerve cells o Toxin diffuses throughout body via blood Cardiac, neurologic complications Heart/respiratory damage, paralysis NH3+ =5 Coated pit 1pH5. Endosome Receptor surface 灯可r Result: Protein synthesis inhibition and cell death AD++ EF-2 ADPR-EF-2+ nicotin
Diphtheria Toxin (DT) ⚫ Cleaved to yield A/B fragment, joined by S-S bond - A (catalytic domain) - B (transmembrane and receptor binding domains) ⚫ Receptor: heparin-binding epidermal growth factor - rich on cardiac cells and nerve cells ⚫ Toxin diffuses throughout body via blood - Cardiac, neurologic complications - Heart/respiratory damage, paralysis