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17 Cards in this Set
- Front
- Back
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Streptococci
General characteristics |
Gram + cocci in chains
Variable hemolysis Catalase - Grouped based on cell wall CHO Typed based on surface protein |
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Group A
Beta hemolytic Strep (Strep. pyogenes) General description |
small, white raised colony
Gram + cocci in chains A-disc sensitive (bacitracin) |
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Group A Beta hemolytic Strep.
Virulence factors (structural) |
Hyaluronic acid capsule (anti-phago)
M-protein (anti-phago) Adhesins (binds fibronectin) C5a peptidase (cleaves C5a, no PMN migration) |
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Group A Beta hemolytic Strep.
Virulence factors (secreted) |
Erythrogenic toxin (exotoxin A,B,C) - septic shock
Streptolysins S&O (S= hemolysis, stable to O2; O= cardiotoxin, unstable to O2) Lipases, DNAases, NADase, streptokinase, hyaluronidase |
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Group A Beta hemolytic Strep.
Diseases |
Upper respiratory infection, skin infection, necrotizing fasciitis, acute rheumatic fever, acute glomerulonephritis
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Group A Beta hemolytic Strep.
Rheumatic Fever |
3 weeks after untreated URT infection (not skin!)
Related to school age kids in winter and spring, common in temperate/cold climates Frequent ASO response and many different serotypes involved Most likely mechanism is anitgenic mimicry |
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Group A Beta hemolytic Strep.
Acute Glomerulonephritis |
Follows group A infection of skin OR URT
Mainly preschool age in summer in fall Tropical/hot climates Infrequent ASO response with few serotypes Auto-antibody against basement membrane |
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Group A Beta hemolytic Strep
Treatment |
Penicillin (not resistent yet)
Erythormycin (lots of allergies, resistance developing) Immunization = would need common non-toxic M protein epitope Difficult treatment in deep seated infection (amputation for necrotixing fasciitis, etc.) |
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Group B strep.
Strep. agalactiae Virulence/characteristics |
Group B Antigen
Type III polysaccharide capsule (contains sialic acid which neonates don't respond to) Pili; can cross placenta (but antibodies to it cannot) Responds to penicillin |
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Group B strep.
Diseases |
Neonatal sepsis:
Acute = first 48 hours, hearing loss, mental handicap Delayed = 10 days to 4 months, nosocomial Sexually transmitted dz=asymptomatic vaginal infection in pregnant females (test before delivery!) LEADING CAUSE of neonatal meningitis |
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Group C and Group G Beta hemolytic Strep.
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occasional URT infection without sequelae
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Alpha Hemolytic Strep.
Strep. pneumoniae characteristics |
Gram + lancet shaped diplococci
alpha-hemolytic (green) CAPSULE (type Ag) P-disc sensitive (optochin) Bile solubility (+) umbilicated colony |
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Alpha Hemolytic Strep.
Strep. pneumoniae virulence factors |
Capsule = anti-phago
Pneumolysin Purpura producing principle |
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Alpha Hemolytic Strep.
Strep. pneumoniae Dz and treatment |
Normal flora of nasopharynx and throat
Pneumococcal pneumonia that goes to blood and meninges Usually follows other immune suppressing event; assoc. with alcoholism, sinusitis, OM, meningitis, peritonitis Treat with PCN, vaccine available |
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Alpha Hemolytic Strep
Strep. mutans |
found in mouth, causes dental caries, forms biofilm, must remove to treat
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Alpha Hemolytic Strep
Strep. viridans, Strep. sanguis |
Oral cavity normal flora
Virulence (sanguis): - IgA protease, extracellular glycan, produce peroxidase Dz: bacterial endocarditis (prosthesis or valves) Treat: PCN + aminoglycoside |
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Gamma hemolytic (non) Strep.
Enterococcus faecalis |
Group D Ag
Ferments esculin; isolate on bile media Dz: Acute or sub endocarditis Treat: resistant to everything (use vanco |
