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Scarlet fever. Introduction 1 A kind of acute infectious disease of respiratory tract 2 Group A β-hemolytic streptococcus 3 Main clinical manifestation: acute fever pharyngitis diffuse and red exanthem(rash).
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Scarlet fever Introduction 1 A kind of acute infectious disease of respiratory tract 2 Group A β-hemolytic streptococcus 3 Mainclinical manifestation: acute fever pharyngitis diffuse and red exanthem(rash)
desquamation and hyperpigmentation ******* 2~3weeks later rheumatic fever glomerulonephritis arthritis
Etiology Group A β-hemolytic streptococci 1 Morphology and structure Gram-positive spherical cocci Diameter: 0.6~1.0 μm Capsule(+) flagellum and spore(-) Streptococcus groups: A~H & K~U on the basis of C-carbohydrate within the cell wall Group A : more than 80 immunologically distinct types that are based on differences in the M protein. 2 Pathogenecity M protein: resists phagocytosis
the major virulence factor to neutrophils and platelets Capsule: resist phagocytosis Lipoteichoic acid: another virulence factor bind to fibronectin on the surface of epithelial cells Pyrogenic toxin: produce rash, fever
resist phagocytosis, promote Schwartzman reaction Streptokinase Streptodornase Streptolysin O & S: WBC, RBC & platelet Hyaluronidase: hyaluronic acid
Epidemiology 1 Source of infection: Patients in scarlet fever or pharyngitis Carriers with streptococci in nasal and pharyngeal 2 Route of transmission: droplet, skin lesion, food, milk and water and so on. 3 Susceptibility of population Anti-bacterium immunity anti-M Anti-pyrogenic toxin immunity
4 The feature of epidemiology season, age, endemic area, variation of this disease*
Pathogenesis 1 Suppurative change Pathogen----epithelial cells----diffusion in local tissue LTA hyaluronidase M protein streptokinase, streptodornase capsule streptolysin -----------suppurative change pharyngitis, tonsillitis peritonsillar abscess retropharyngeal abscess otitis media, sinusitis lymphangitic-----lymphadenitis bacteremia(sepsis, osteomyelitis, pneumonia)
2 Toxic change pyrogenic exotoxin (erythrogenic exotoxin) fever scarlatina rash other toxic symptoms 3 Allergic reactive change 2~3weeks later, Heart-------rheumatic fever Kidney-----glomerulonephritis joint---------arthritis reason: 1)similar antigen----crossed immune reaction 2)immune complex
Clinical manifestation Incubation period2~3days(1~7days) Character of clinical manifestation: Fever Pharyngitis scarlatina rash 1 Fever 1) feature: persistent, fever & rash* 2) tem. : 39~40℃ 3) accompanied symptoms: headache, weakness, poor appetite 4) course: 1 week
2 Pharyngitis symptom sign 3 Rash 1) fever & rash**: 24 hours 2) initial position: ear , neck, upper chest 3) feature: diffuse papular(punctate or finely) miliary sudamina (not so many) circumoral pallor strawberry tongue red strawberry tongue Pastia lines(antecubital fossate) desquamation and hyperpigmentation
Type of clinical manifestation light type toxic type sepsis type surgery type obstetrics type
Laboratory examination 1 peripheral picture: WBC, neutrophil 80% 2 Urine allergic reaction : protein RBC, WBC, cylindruria 3 bacteriology test: Immunological fluorescence assay(IFA) bacteria culture
Complication 2~3 weeks later rheumatic fever glomerulonephritis arthritis
Diagnosis 1 clinical data: fever, pharyngitis, rash 2 laboratory test: peripheral picture, Urine Bacteriology test Dick test ( pyrogenic test) 3 epidemiology data
Differential diagnosis 1 staphylococcus infection 2 drug rash 3 Virus rash measles, rubella etc.
Treatment 1 penicillin adult: 80万U/ time, bid 5~7days. child:20万U/(kg d), 10days 800万U/d(adult) 2 erythromycin
Prevention 1 Isolation: patients in scarlet fever 2 protection: