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17 Cards in this Set

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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
Group A
Beta hemolytic Strep
(Strep. pyogenes)
General description
small, white raised colony
Gram + cocci in chains
A-disc sensitive (bacitracin)
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)
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
Group A Beta hemolytic Strep.
Diseases
Upper respiratory infection, skin infection, necrotizing fasciitis, acute rheumatic fever, acute glomerulonephritis
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
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
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.)
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
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
Group C and Group G Beta hemolytic Strep.
occasional URT infection without sequelae
Alpha Hemolytic Strep.
Strep. pneumoniae
characteristics
Gram + lancet shaped diplococci
alpha-hemolytic (green)
CAPSULE (type Ag)
P-disc sensitive (optochin)
Bile solubility (+)
umbilicated colony
Alpha Hemolytic Strep.
Strep. pneumoniae
virulence factors
Capsule = anti-phago
Pneumolysin
Purpura producing principle
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
Alpha Hemolytic Strep
Strep. mutans
found in mouth, causes dental caries, forms biofilm, must remove to treat
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
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