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1/01 UPPER RESPIRATORY SYSTEM INFECTIONS Streptococcus species Gram pos. cocci, chains Three groups: 1) Beta hemolytic - most virulent 2) Alpha hemolytic - opportunists 3) Gamma hemolytic - nonhemolytic, nonpathogenic Streptococcal Pharyngitis ("Strep throat") - Streptococcus pyogenes Virulence: Encapsulated, M-proteins in cell walls, leukocidins, beta-hemolysins, streptokinase, hyaluronidase Transmission: URT secretions - droplet nuclei (adult carriers) P/E: Nasopharynx Disease: Localizes on m.m. tonsils, pharynx secretes enzymes inflammation. M.m. become red, swollen, purulent exudate (pus), hemorragic patches, high fever, pain, enlarged lymph nodes. Identification: Hemorragic patches, purulent exudate, throat swab. Complications: 1) Rheumatic fever - antibodies cross react with tissues of heart, joints - autoimmune disease 2) Glomerulonephritis - Ag-Ab complexes filtered out in kidneys damage kidney (glomerular capillaries) - autoimmune disease Immunity: None Scarlet fever - S. pyogenes Virulence: Erythrogenic exotoxin (due to lysogenic prophage lysogenic conversion); also see virulent characteristics above Transmission: Droplet nuclei P/E: Nasopharynx, oral cavity Disease: Onset identical to “strep throat”. Exotoxin produced blood stream skin. Causes red rash on face, neck chest, abdomen extremities. Bright red tongue ("Strawberry" tongue) appears before rash. Skin peels, fever, chills, vomiting. Complications: Rheumatic fever, glomerulonephritis (autoimmune diseases) Immunity: Ab develop to exotoxin but not to organism Diphtheria - Corynebacterium diphtheriae Gram pos. bacillus Virulence: potent dermonecrotic exotoxin (due to lysogenic prophage lysogenic conversion) Transmission: URT secretions - droplet nuclei. Adult carriers. P/E: Nasal passage. Localizes in pharynx Disease: Inc. pd. 2 - 5 days. Secretes exotoxin necrosis superficial tissues ulceration marked inflammation thick (leather-like) exudate forms pseudomembrane blocks trachea suffocation death. Complications: Exotoxin enters bloodstream damages heart, kidneys, CNS. Vaccine: D PT - toxoid 1
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1/01 Bacterial (Contagious) Conjunctivitis (Pink Eye) - Haemophilus aegypticus, H. influenzae Gram neg. bacillus Virulence: Encapsulated, endotoxins (lipids in cell walls) Transmission: Eye, nasal secretions (extremely contagious). Most common vector - hands. P/E: Nasopharynx, conjunctiva Disease: Multiplies on conjunctiva marked inflammation red, swollen eyes, purulent exudate, photophobia. Immunity: none Common Colds - Flu-like Illnesses Many viruses are causative agents: 1) Rhino viruses - most common, approx. 100 types, limited to nasal passage. 2) Reoviruses
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