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Infectious Disease Final > Lecture 8 -- Streptococci > Flashcards

Lecture 8 -- Streptococci Flashcards

1
Q

what bacteria causes strep throat?

A

streptococci pyogenes

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2
Q

what disease(s) does streptococci agalactiae cause?

A

sepsis in newborns

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3
Q

what disease(s) does streptococci pneumoniae cause?

A

pneumonia and meningitis

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4
Q

name 3 streptococci species commonly associated with human disease

A

streptococci pyogenes
streptococci agalatiae
streptococci pneumoniae

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5
Q

are streptococci gram (+) or gram (-)

A

gram (+)

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6
Q

are streptococci catalase (+) or (-)

A

(-)

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7
Q

are streptococci aerobic or anaerobic

A

anaerobic

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8
Q

how do streptococci grow?

A

in pairs or chains

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9
Q

do streptococci have spores? do they have flagella?

A

neither

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10
Q

differentiate between the capsule of staphylococci and streptococci

A

capsule of staphylococci is made of polysaccharides

capsule of streptococci is made of hyaluronic acid that blends in with the hyaluronic acid of human connective tissue to evade the immune system

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11
Q

what is unique about the requirements for streptococci to grow

A

streptococci has complex nutritional requirements in order to grow

produce lactic acid by the fermentation of carbohydrates

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12
Q

name the 3 main GROUPS of streptococci and explain them

A
  1. streptococci (different variations of carbohydrate chains called LANCEFIELD CELL WALL ANTIGENS. different from strain to strain)
  2. pneumococcus – ONLY includes streptococci pneumoniae
  3. viridians – resident oral microbiota
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13
Q

state the important lancefield classifications relevant to human disease

A

group A strep – streptococci pyogenes
group B strep – streptococci agalctiae

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14
Q

streptococcal groups (streptococci, pneumococcus, viridians) are also classified based on ____ patterns

A

HEMOLYTIC (ability to lyse red blood cells)

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15
Q

explain the hemolytic pattern classification for streptococci

A

beta hemolytic – complete hemolysis (streptococci)

alpha hemolytic – incomplete hemolysis (pneumococcus and viridians)

gamma hemolytic = non hemolytic. dont produce porin toxins

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16
Q

which streptococci are beta hemolytic? what does this mean?

A

streptococci (classified by lancefield cell wall antigens.GAS and GBS)— they can completely lyse RBCs

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17
Q

which streptococci are alpha hemolytic? what does this mean?

A

incomplete hemolysis

pneumococcus and viridians

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18
Q

differentiate between the capsules of streptococcus pyogenes, streptococcus agalactiae, and streptococcus pneumoniae

A

pyogenes – hyaluronic acid
agalactiae – sialic acid
pneumoniae – polysaccharide

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19
Q

which streptococcus has M protein as a surface protein?
it is homologous to what other surface protein?

A

streptococcus pyogenes
it is homologous so Surface Protein A (SpA) of staphylococcus aureus – binds antibodies upside down

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20
Q

which group of streptococci has strepSAgs?

A

streptococcus pyogenes

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21
Q

what is the name of the porin protein for streptococcus pyogenes? what about streptococcus pneumoniae?

A

streptococcus pyogenes – streptolysin O
streptococcus pneumoniae – pnemolysin

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22
Q

which group of streptococcus can cause toxic shock syndrome with the production of superantigens?

A

strptococcus pyogenes

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23
Q

which group of streptococcus causes impetigo (school sores)

A

streptococcus pyogenes (group A strep GAS)

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24
Q

which bacteria avoids opsonization and phagocytosis due to its capsule?

A

GAS (streptococcus pyogenes) – due to hyaluronic capsule. poses as host

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25
Q

how does streptococcus pyogenes invade cells?

A

by binding to factor H – a complement control protein on the host cell surface

26
Q

besides staphylococcus aureus, what other bacteria binds fibronectin and through what?

A

through F protein AND lipoteichoic acid – GAS (streptococcus pyogenes)

27
Q

explain how streptococcus pyogenes can invade the host complement system

A

has an M protein that blocks C3b binding
has C5a peptidase to inactivate C5a

28
Q

what does streptococcus pyogens have that enables it to evade opsonization/neutralization

A

M-like surface proteins that bind the Fc regions of antibodies (upside down)

hyaluronic acid

29
Q

name the 5 toxins/enzymes that streptococcus pyogenes utilizes

A

superantigens
streptolysin S – a hemolysin
streptolysin O – a hemolysin
streptokinases – lyse clots
Dnases A-D – degrade host DNA

30
Q

Streptococcus pyogenes is Beta hemolytic.
name the porin protein(s)

A

streptolysin S and Streptolysin O

31
Q

GAS can cause ____ or ____ diseases

A

Suppurative or nonsuppurative (pus forming)

32
Q

name the 5 pus forming diseases caused by GAS

A

-pharyngitis
-impetigo
-erysipelas
-cellulitis
-necrotizing fasciitis

33
Q

name the non-supparative diseases caused by GAS

A

rheumatic fever
acute glomerulonephritis

34
Q

what is also known as scarlet fever? what causes it?

A

pharyngitis
GAS

35
Q

pharyngitis is ___ mediated

A

bacteriophage

36
Q

what is rheumatic fever?
what causes it?

A

complications of pharyngitis that involve the heart, blood vessels and joints

occurs when GAS gets into the bloodstream

37
Q

what is the only member of the GBS family

A

streptococcus agalactiae

38
Q

streptococcus agalactiae is ___ hemolytic

A

beta, but there are a few gamma

39
Q

of the 3 main species of streptococcus, which can colonize the GI tract? explain

A

streptococcus pyogenes and streptococcus agalactiae

this is because pyogenes has a hyaluronic acid capsule and agalactiae has sialic acid capsule. both are well protected to survive the conditions of the GI tract

40
Q

explain the significance of the fact that streptococcus agalactiae can colonize the genitourinary tract

A

this bacteria primarily infects newborns – can catch right after being born or even in utero

there is both early onset and late onset

41
Q

what is required to kill group B strep?

A

the activation of both the ALTERNATIVE and CLASSICAL complement pathways

42
Q

true or false

group B strep has only 1 virulence factor

A

TRUE – its the sialic acid capsule. avoids phagocytosis

43
Q

explain the entire capsule/ outer surface of group B strep

A

has sialic acid capsule to avoid phagocytosis.
also, has type-specific capsular carbohydrates (9 diff ones)

the sialic acid capsule can bind factor H and evade the complement system by breaking down C3b

also has PILLI that can bind to fibronectin on the host cell membrane

44
Q

explain the difference between early onset and late onset neonatal disease of GBS

A

early onset == acquired in utero or at birth
disease = bacteremia, pneumonia or meningitis. sepsis. signs start showing up during first 7 days of life

late onset == starts showing up 1 week - 3 months after birth. EXOGENOUS SOURCE – we’re not sure where it came from
bacteremia with meningitis

45
Q

name the symptoms that can be caused by a GBS infection

A

postpartum endometriosis
UTI
bacteremia
pneumonia
bone and joint infections
skin and soft tissue infections

46
Q

is streptococcus pneumoniae encapsulated?

A

yes, with a polysaccharide capsule there are 90 different serotypes of the capsule

47
Q

streptococcus pneumoniae are ____ hemolytic

A

alpha, but there are a few beta

48
Q

which streptococci is diplococci?

A

streptococcus pneumoniae

49
Q

which streptococcus PRODUCES lactic acid?

A

streptococcus pneumoniae

50
Q

where does streptococcus pneumoniae colonize?

A

the nasopharynx and oropharynx

51
Q

explain how streptococcus pneumoniae colonizes

A

initially colonizes through binding to PHOSPHO-CHOLINE on the host cell membrane.

streptococcus pneumoniae has choline binding proteins

52
Q

explain the structure of streptococcus pneumoniae

A

elongated, diplococci

53
Q

pnemococcus primarily enters through….

A

inhalation

54
Q

pneumococcus can cause….

A

pneumonia and meningitis once it gets into the bloodstream

55
Q

_____________ allows for the spread of streptococcus pneumoniae

A

the evasion of immune-cell mediated destruction

56
Q

explain how pneumococcus effectively infects the lung area

A

pneumococcus bacteria is inhaled in.
it contains a secretory IgA protease. Thus, it degrades the IgA antibodies on the mucosal surfaces of the resporatory tract to easily infect and get into the bloodstream

also has PNEUMOLYSIN to form pores in epithelial cell walls and SUPPRESS the oxidative burst of phagocytes that is meant to kill them
also, activates the complement pathway to promote inflammation

57
Q

name all of the virulence factors of pneumococcus

A

-secretory IgA protease
-Neuraminidase
-polysaccharide capsule
-pneumolysin
-surface choline binding protein

58
Q

in order to develop pneumonia, what must happen?

A

ANTIBODY MEDIATED KILLING – destruction of IgA by IgA protease on pneumococcus

59
Q

explain what pneumonia is

A

when pneumococcus colonizes in the alveoli of the lungs, pneumolysin destroys many epithelial cells, creating a lot of cell debris and fluid in the alveolar spaces

60
Q

besides pneumonia, what else can streptococcus pneumonia cause?

A

sinusitis
otitis media (middle ear infection)
meningitis (following a ear or sinus infection)
bacteremia — heart valve tissue destruction

61
Q
A

Infectious Disease Final (13 decks)

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