MIDTERM 2 - Streptococcus Flashcards
= gram (+) cocci
= arranged in pairs or in chains
= catalase negative
Genus Streptococcus
very small zone of NO HEMOLYSIS and then a wider zone of β-hemolysis; mistaken as β hemolysis at first glance
Hemolytic pattern on sheep’s blood agar
= fastidious; grown in enriched media
= most are facultative anaerobes
= non-motile but would just grow along the stab line or
along the line of inoculation
Genus Streptococcus
classic strep throat; red swollen tonsils and pharynx; a purulent exudate on tonsils, fever,
swollen lymph nodes that usually lasts 5 days
Streptococcal pharyngitis
also known as Wide Zone
Alpha-Prime (α’)
type of infection, site of origin
Physiologic characteristics
enzyme destroys RBC & WBC and is the reason for beta-hemolytic ability
Streptolysin O
Lancefield antigens are given letter names_____________
through S.
A, B, C, D, E,
In Streptolysin S, S stands for _____
oxygen stabile
C carbohydrate present or extracted from the cell wall
Lancefield classification
antigen causing increased ASO titer
Streptolysin O
also responsible for beta-hemolysis but is not antigenic
Streptolysin S
more than 30 species of streptococci, only 5 are
significant human pathogens; Three of these pathogens have Lancefield antigens: Lancefeld group ___________
Lancefeld group A, B and D
major virulence factor for group A streptococcus. It inhibits the activation of complement and protects from phagocytosis; However, it is also the weakest point in the organism’s defense
M protein
pus-producing; strep throat, scarlet fever, rheumatic fever, & post-streptococcal
glomerulonephritis
Group A Beta-hemolytic Strep
cause scarlet fever; causes streptococcal toxic shock syndrome
Pyrogenic exotoxin | erythrogenic toxin
In Streptolysin O, O stands for _______ as it is inactivated by oxygen
oxygen labile
flesh eating strep; break in skin caused by trauma then follow a
path along fascia; patient develops swelling, heat, & redness that moves rapidly from initial infection site; day later skin changes from red to purple to blue, & large blisters form; later skin dies & muscle become infected
Necrotizing Fasciitis
produced pyrogenic toxin or erythrogenic toxin; fever, sorethroat & scarlet-red rash; rash begins on trunk and neck then spreads to extremities, sparing the face; strawberry tongue
Scarlet fever
Streptolysin S, S stands for _____
oxygen stabile
also responsible for beta-hemolysis but is not antigenic
Streptolysin S
infection of the dermis; raised, bright red rash with sharp
border
Erysipelas
similar to scarlet fever, also mediated by the release of pyrogenic toxin; signs and symptoms are similar with staph TSS
Streptococcal toxic shock syndrome
affects children 5-15 years of age; follows untreated streptococcal pharyngitis
NOT after a skin infection
Rheumatic fever
