Streptococci and Enterococci 9/2/15 Flashcards
Name the species of Streptococci associated with the Lancefield groups A and B.
- Group A: Streptococcus pyogenes
- Group B: Streptococcus agalactiae
Apples and Bananas (A = p, B = a)
What are some differences between Staphylococci and Streptococci?
-Staph: catalase positive
–Cocci in clusters
–Minimal media
–Aerobic preference
–Toxic Shock Syndrome
-Strep: catalase negative
–Cocci in pairs and chains
–Complex media
–Anaerobic/CO2 pref.
–Toxic Shock-like Syndrome
List 7 clinical manifestations of Streptococcus pyogenes infection.
- Acute Pharyngitis: fever, sore throat, headache, self-limiting
- Impetigo: pustule with yellow crust, assoc. w/trauma/bug bites
- Erysipelas: spreading erythema w/well demarcated edge on face/leg
- Scarlet Fever: sore throat, fever, “strawberry” tongue: think “strawberry pie”
- Necrotizing Fasciitis: “flesh eating” bacteria, destruction of mm and fat (deep tissue infection)
- Toxic Shock-like Syndrome: from pyrogenic exotoxin, positive for group A strep, multisystem organ failure
- Puerperal Sepsis: women after delivery, endometritis, bacteremia, necrotizing fasciitis, etc.
Name 2 diseases that occur as sequelae to streptococcal infections and describe their clinical presentation.
-
Rheumatic Fever:
- non-suppurative inflammation 1-5 wks after infection
- fever, carditis, polyarthritis, chorea
- ASCHOFF bodies and valve damage -
Acute Glomerulonephritis:
- Edema, HTN, hematuria, proteinuria
- Antigen + Antibody + Complement deposit in glomeruli
Name 4 virulence factors associated with Streptococcus pyogenes and the mechanisms by which they enhance infection.
- Streptococcal Pyrogenic Exotoxins (SPE)
- heat labile toxins
- Strep toxic shock-like syndrome
- rash in scarlet fever “erythrogenic exotoxin” - M protein (>80 serotypes)
- antiphagocytic
- degrades complement C3b - Streptolysins O -allow spread of bacteria into tissues
- Streptokinase -same as above
What are the limitations of Rapid Group A Detection kits?
They don’t have high sensitivity: -Have to do a back up culture to make sure patient is actually Strep A negative
What are the treatment options for S. pyogenes?
-
PENICILLIN, ampicillin/amoxicillin
- No resistance worldwide - Cephalosporins
- Erythromycin -Penicillin allergic patient
What is the role of S. agalactiae (GBS) in causing neonatal disease?
-Maternal colonization of vagina/rectum exposes baby at delivery -Lack of protective maternal antibody
How can neonatal disease from S. agalactiae be prevented?
-Perform cultures of vagina/rectum at 35-37 weeks gestation -Give GBS + women pen/amp during labor -Treat babies as if they’re GBS + if prenatal history UNKN
What species of Streptococci are included in the Strep Milleri Group?
–Butterscotch odor: pyogenic infections of cardiac, abdominal, skin and CNS tissues
-S. anginosus -S. constellatus -S. intermedius
“Armies Can Invade”
The following species of Streptococci are in what group: -Abiotrophia -Granulicatella
Nutritionally deficient Strep Group: -Vitamin B6 deficient -Satellite colonies -Endocarditis
What are the 2 major species of Enterococcus causing infection in humans?
- E. faecalis 2. E. faecium
Describe the penicillin/ampicillin susceptibility and resistance of major species of Enterococci.
-E. faecalis: susceptible to pen/amp
-E. faecium: resistant to pen/amp
**Intrinsically resistant to all cephalosporins, trimethoprim-sulfa, aminoglycosides
-Vancomycin resistant enterococci: susceptible to Linezolid
List 3 most common infections caused by Enterococci.
- UTI 2. Mixed bacterial wound infections and decubiti 3. Sepsis, endocarditis
Identify key morphologic and phenotypic tests used for identification of S. pneumoniae
- Gram stain: gram +, lancet shaped, diplococci
- Blood agar: alpha hemolytic
- Biochemical Tests: Catalase negative, bile soluble, inhibited by ethylhydrocupreine (Optochin)
