6. Respiratory Infection

6. Respiratory Infection - 6. Common Diseases Transmitted...

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Unformatted text preview: 6. Common Diseases Transmitted by Respiratory Infection 2 Streptococcal Diseases - Upper Respiratory Tract Streptococcus encapsulated gram +ve chain-forming Bacterial Respiratory Infection Streptococci 3 Classification: hemolytic pattern: Beta clear zone due to complete destruction Alpha green zone on blood agar due to incomplete hemolysis Gamma no hemolysis Lancefield classification: based on variants of carbohydrate in cell wall A - O most disease by Group A strep S. pyogenes is most common, a.k.a. Group A -hemolytic strep Bacterial Respiratory Infection Streptococci 4 Group A strep (GAS) Streptococcus pyogenes 10-20% carrier rate Pharyngitis (strep throat) a primary disease in pharynx transmission: droplets incubation: 1-3 days symptoms: high fever swollen lymph nodes/tonsils bright red pharynx tissue Bacterial Respiratory Infection Streptococci 5 M protein in cell wall and pili enhances attachment and inhibits phagocytosis (adhesin, evasin) 60 antigenic types makes vaccine development difficult Bacterial Respiratory Infection Streptococci M protein 6 Scarlet fever - Group A strep plus toxin strep throat along with a skin rash (pink-red blush on neck, chest, part of arms, strawberry tongue) due to erythrogenic toxin capillary wall damage blood leaking toxin only produced by certain strains antibody to toxin provides immunity to scarlet fever rash (not strep throat) Bacterial Respiratory Infection Streptococci 7 immune complications of GAS (1-4 weeks after acute infection) rheumatic fever characterized by fever, inflammation of small blood vessels, joint pain, permanent scarring of heart valves valve damage: Ab specific to strep Ag cross-reacts with heart tissue glomerulonephritis inflammation in kidney can cause permanent kidney damage Bacterial Respiratory Infection Streptococci 8 Other GAS diseases Depends on portal of entry, additional virulence factors Skin infection Erysipelas disease spreads from wounds and abrasions red well-defined skin eruptions Impetigo vesicles, pustules (purulent vesicles), crusted Bacterial Respiratory Infection Streptococci 9 Blood infection Septicemia blood poisoning, from surgical or traumatic wounds Puerperal sepsis- childbed fever Infection of uterus following childbirth Develops into septicemia Bacterial Respiratory Infection Streptococci 10 Severe invasive GAS additional virulence factors Necrotizing fasciitis (flesh-eating bacterium) GAS-infected wounds extensive damage of soft tissue extremely rapid spread - excavation/amputation to treat Bacterial Respiratory Infection Streptococci 11 Severe invasive GAS additional virulence factors Pneumonia respiratory infection rapidly fatal rare - most famous case: Jim Henson Bacterial Respiratory Infection Streptococci...
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6. Respiratory Infection - 6. Common Diseases Transmitted...

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