EX2 Streptococci - Bailey Flashcards
What type of gram stain is strep
gram +
what shape is strep, and what does it form
cocci
chains or diplococci
Is strep spore forming?
no, non-spore forming
What level of oxygen does strep need to survive
facultative anaerobe; can grow with our without
Is strep catalase negative or positive
catalase negative; does not break down H2O2
What is the lancefield group test
serological classification based on major cell-wall carbohydrate antigens; agglutination = positive
This type of hemolysis is partial hemolysis and green discoloration of hemoglobin
alpha
This type of hemolysis is complete hemolysis with a clear zone
beta
In this type of hemolysis there is no some of clearing
gamma
What is the most common disease of group A strep
acute pharyngitis; strep throat
These are all diseases of what class of strep; pyoderma, nectrotizing fasciitis, myositis, childbed fever, and foodborne outbreaks
group A strep
What is caused by strep throat and a red skin rash; caused by GAS
scarlet fever
What is the main bacteria of GAS
S. pyogenes
This can result in the inflammation of heart/joints, polyarthritis/caritis, severe vascular scarring
nonsuppurative sequelae; non-pus forming secondary results of ARF
This was fairly common until the mid-20th century
acute rheumatic fever
If there is an infection in this location, ARF may form, but if not, then no ARF
pharynx
True or False
An ARF infection must invoke an immune response
True; hypersensitivity reaction caused by cross-reacting antibodies
True or False
No more than 10% of people are susceptible to ARF
True
How can you completely prevent ARF
by treating strep throat with penicillin
This is active inflammation in the glomeruli of the kidneys; urine is smoky due to proteins, leukocytes, and erythrocytes, renal failure –> dialysis
acute post-streptococcal glomerulonephritis (APSGN)
APSGN different from ARF how
can follow skin infections
susceptibility common
recurrent attacks are rare
not reliably prevented by penicillin
True or False
Not all GAS cause APSGN
True
How can one encounter GAS infections
they live on skin and mucous membranes
person to person transmission
True or False
GAS can penetrate intact skin
False; it cannot penetrate intact skin
How do GAS bind to epithelial cells
via adhesions
What type of adhesions doe GAS use to bind to epithelial cells
Lipoteichoic acid (LTA)
Protein F
M protein
This is found in the cell envelope of many gram + bacteria, making them sticky, and it binds to fibronectin
lipoteichoic acid
This is a high affinity fibronectin binding protein
protein F
This is a keratinocyte (outer skin) adhesion
M protein
What determines how a GAS infection spreads
how the infection was acquired; skin/mucous membrane tend to stay localized but deep tissue tends to spread rapidly
This breaks down fibrin, disrupting clot formation
streptokinase
What do bacteria use to avoid phagocytosis
antiphagocytic factors
This is the most important antiphagocytic factor, it is central to pathogenesis and required for virulence
M protein
This is a mucoid capsule
hyaluronic acid capsule
This inactivated phagocyte chemotaxin
C5a peptidase
This blocks complement from binding to the cells, inhibits the formation of opsonizins, and forms a dense coating on bacterias surface
M protein
What makes M protein so hard to target
There are nearly 100 serotypes
True or False
The hyaluronic acid capsule on strep is that same as the polysaccharide capsule on staph
false; they are not the same
What does the hyaluronic acid capsule do
makes strep “slippery,” interfering with phagocytosis
ARF isolates are heavily encapsulated
This will destroy hyaluronic capsules
hyaluronidase
True or False
GAS invokes intense inflammatory response in tissues
True
These can mimic the effects of endotoxins, are responsible for the red rash of scarlet fever, and produce streptococcal toxic shock syndrome
superantigens
True or False
Group B strep is more common, though less notorious than group A
True
Where do GBS inhabit
lower GI and female genital tract
What does GBS cause
neonatal spesis and meningitis
cellulitis, arthritis
GBS has what type of capsule
polysaccharide (different from GAS)
Which groups are included in other β-hemolytic strep
groups C, G, and F
What do groups C, G, and F have in common with and B
M protein
bind fibrinogen
secrete extracellular enzymes
Which groups also has a hyaluronic acid capsule
C
Group D strep undergoes what type of hemolysis
α or γ
What describes group D strep and where is it found
enterococci and nonenterococci
normal flora of GI and genitourinary tract
What are considered “world’s toughest pathogenic bacteria”
enterococci
What is required for killing of enterococcil; which antibiotic are some resistant against
antibiotic synergism
vancomycin
What type of bacteria and conditions are a result of nonenterococci
S. bovis
subactue bacterial endocarditis
bacteremia
True or False
Nonenterococci can grow in high salt and are killed by penicillin
False; enterococci can grow in salt, but are not killed by penicillin
This is the most common cause of subacute bacterial endocarditis, and 30-60% of the oropharyngeal flora, is α-hemolytic
viridans strep
True or False
Enterococci have a low virulence, but are very resistant
True
Viridans strep consists of what strep family
S. mutans (causes caries)
S. mutans thrives on which substance
sucrose; fermenting it, causing acid
