Ch. 15 - Streptococcus Flashcards
Catalase reaction of Streptococcus
Catalase negative
Gram reaction of Streptococcus
Gram positive
Test that differentiates Streptococcus and Enterococcus from Staphylococcus
Catalase Test
Streptococcus and Enterococcus are Catalase negative
Description of colonies of Streptococcus
Pinpoint colonies (small & transparent)
Type of hemolysis where there is partial lysis and greenish coloration
Alpha hemolysis
Type of hemolysis where there is complete lysis; there is a clear area
Beta hemolysis
Type of hemolysis where there is no lysis; there is no change in the agar
Nonhemolytic/gamma hemolysis
Type of hemolysis where there is a small area of intact RBCs; there is wider zone of complete hemolysis
Alpha-prime
Lancefield group of Streptococcus pyogenes
Lancefield Group A
Virulence factor of S. pyogenes; attached to the peptidoglycan of the cell wall; part of antigenic structure of S. pyogenes
M protein
Substance in S. pyogenes that makes it resistant to phagocytosis; it is used for adherence of the bacterial cell to mucosal cells
M protein
2 virulence factors of S. pyogenes that mediate adherence to host epithelial cells
- Lipoteichoic acid
- Protein F
Virulence factor of S. pyogenes that prevents opsonized phagocytosis; masks its antigens to remain unrecognized
Hyaluronic Acid Capsule
Virulence factor of S. pyogenes that is antigenic
Deoxyribonucleases (A, B, C, and D)
2 hemolysins produced by S. pyogenes; virulence factors
- Streptolysin O
- Streptolysin S
Hemolysin of S. pyogenes that is oxygen-labile
Streptolysin O
Hemolysin of S. pyogenes that is highly immunogenic/antigenic
Streptolysin O
Antibody that is tested for recent infection of S. pyogenes
Antistreptolysin-O (ASO) antigen
3 cells lysed by the hemolysins of S. pyogenes
- erythrocytes
- leukocytes
- platelets
Hemolysin of S. pyogenes that is oxygen stable
Streptolysin S
Hemolysin of S. pyogenes that is non-immunogenic/non-antigenic
Streptolysin S
3 enzymes that are S. pyogenes virulence factors
- Streptokinase
- Hyaluronidase
- Streptodornase
Enzyme by S. pyogenes that lyses fibrin clots
Streptokinase
Enzyme by S. pyogenes that is a spreading factor; contributes to its invasiveness
Hyaluronidase
Enzyme by S. pyogenes that dissolves purulent or fibrinous secretions
Streptodornase
Toxin produced by S. pyogenes
Erythrogenic toxin
Disease caused by erythrogenic toxin
Scarlet fever (red spreading rash)
3 superantigens of erythrogenic toxin
- SpeA
- SpeB
- SpeC
Produced by erythrogenic toxins that are highly mitogenic proteins; they stimulate T-lymphocyte proliferation which induces production of IL-1, tumor necrotizing factor and other cytokines
Superantigens (SpeA, SpeB, and SpeC)
Infection by S. pyogenes; “Strep throat”; characterized by sore throat, malaise, fever, and headache
Bacterial pharyngitis amd tonsilitis
2 methods for diagnosis of S. pyogenes bacterial pharyngitis and tonsilitis
- Throat culture
- Direct Antigen Detection
2 MOTs of S. pyogenes in bacterial pharyngitis and tonsilitis
- droplet
- close contact
Pyodermal infection by S. pyogenes associated with young children (2-5 yrs old); affects exposed areas of skin; inoculation through minor abrasions or insect bites
Impetigo
Pyodermal infection by S. pyogenes in elderly patients; acute spreading skin lesion; erythematous with plain demarcation but irregular edge
Erysipelas
Pyodermal infection by S. pyogenes with deeper invasion; may be life threatening; with bacteremia or sepsis; patients with peripheral vascular disease or diabetes may have gangrene
Cellulitis
2 tests for diagnosis of Scarlet fever
- Dick’s test
- Schultz-Charlton Reaction
Susceptibility test for scarlet fever; erythrogenic toxin is injected; positive when there is redness or swelling
Dick’s test
Diagnostic test for scarlet fever; used to differentiate scarlet fever from measles; antierythrogenic toxin is injected; rash will blanch then fade
Schultz-Charlton Reaction
Substance that is injected in Dick’s Test
Erythrogenic toxin
Substance that is injected in Schultz-Charlton Reaction
Antierythrogenic toxin
“Flesh-eating” disease by S. pyogenes; rapidly progressing inflammation of the skin, subcutaneous fat, and fascia; life threatening; occurs when one has suffered trauma to the skin (portal of entry)
Necrotizing fasciitis
Disease by S. pyogenes that causes an entire organ to shut down leading to death
Streptococcal Toxic Shock Syndrome
2 conditions under Post-Streptococcal Sequelae caused by S. pyogenes
- Rheumatic fever
- Acute glomerulonephritis
Post-streptococcal sequelae characterized by fever and inflammation of the heart, joints, blood vessels and subcutaneous tissue; associated with Class I M protein
Rheumatic fever
Post-Streptococcal Sequelae characterized by damage to the glomeruli and impairment of kidney function; associated with Class I & II M protein
Acute glomerulonephritis
2 drugs for the treatment of post-streptococcal sequelae
- Penicillin
- Erythromycin (for patients allergic to penicillin)
M protein associated with Rheumatic fever
Class I M protein
M protein associated with acute glomerulonephritis
Class I & II M protein
Specimen for S. pyogenes laboratory diagnosis
Swab over the posterior pharynx
Plate used for isolation of S. pyogenes
SBA plate containing SXT