Streptococci Flashcards
3 streps in this lecture?
pyogenes, agalactiae, pneumoniae
Is strep an aerobe, anaerobe, or facultative anerobe?
Facultative anerobe
How does alpha hemolysis look on blood agar plate?
Green
How does beta hemolysis look on blood agar plate?
clear
How does gamma hemolysis look on blood agar plate?
Almost like there’s no hemolysis
Strep pyogenes is in what Lancefield group?
Group A strep (GAS) and beta hemolytic
Strep agalactiae is in what group?
Group B strep (GBS) and also beta hemolytic
Strep pneumoniae and strep viridans are in what group?
Untypable using this system, alpha hemolytic
Catalase/coagulase tests for strep are?
Negative/negative
What are Lancefield antigens?
Characterize Strep on the basis of reaction of antibodies to species specific antigens (serology)
Group A strep has what kind of capsule?
Hyaluronic acid capsule
What protien is a group A strep virulence factor and can lead to rheumatic heart disease from molecular mimicry?
M protein
This Group A strep virulence factor is an adhesin and also a PAMP
Lipotechoic acid (LTA)
What virulence factor is strep’s superantigen?
Streptococcal pyrogenic exotoxin A (SpeA)
Very common strep infection that occurs in the throats of children
Pharyngitis (strep throat)
How do you treat pharyngitis?
Give penicillin to prevent development of ARF
What can follow a pharyngeal infection with group A beta hemolytic strep?
Acute rheumatic fever
This disease became almost obliterated when docs started washing their hands inbetween delivering babies
Endometritis
This strep infection is a pyoderma (purulent skin infection) that is common in children
GAS impetigo
Deeper impetigo with ulceration is known as
Ecthyma
This streptococcal cellulitis is characterized by erythema and edema with rapidly advancing, well demarcated edges
Erysipelas
This strep infection is an acute inflammatory condition of the skin that is deeper than impetigo or erysipelas.
Cellulitis
Signs of cellulitis?
Localized pain, erythema, swelling, and heat
This streptococcal induced infection is rapidly spreading and very fatal. It is characterized by EXTREME PAIN OUT OF PROPORTION TO THE APPEARANCE OF THE LESION
Necrotizing fasciitis
How fast can necrosis spread with necrotizing fasciitis?
1 inch per hour
ARF usually develops after
Pharyngitis
Guidelines for diagnosis of ARF (acute rheumatic fever) are?
Jones criteria
Treatment of strep pyrogenes?
Penicillin
Invasive infections by strep pyogenes require what 4 things?
- you must monitor CO and BP
- IV infusion for hypotension
- Renal failure may call for dialysis
- IV Ig
Test for Strep agalactiae (GBS)?
CAMP test
Bigtime GBS virulence factor?
Capsule, capsule, capsule
Viridans strep is alpha or beta hemolytic?
alpha
Where on your body is viridans strep?
oral cavity
How do you distinguish strep viridans from pneumococci?
Viridans is resistant to optochin
Endocarditis of damaged heart valves usually occurs from?
viridans strep.. after a dental procedure, you get bacteremia
These organisms are commensals of the GI tract
Enterococcus
Leading cause of nosocomial infection
Enterococcus
Why are enterococci a big problem?
They are very proficient at taking up DNA and passing it to other species. Enterococci is probably the reason that S. aureus can be vancomycin resistant
