Nelson - Ch. 183 Group A Streptococcus Flashcards

1
Q

The beta hemolytic strep can be divided into groups by this group-specific polysaccharide

A

Lancefield C carbohydrate

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2
Q

Group A strains can be distinguished from other groups by differences in sensitivity to

A

Bacitracin

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3
Q

GAS can be subdivided into more than 220 serotypes in the basis of

A

M protein

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4
Q

T/F M types commonly associated with pharyngitis rarely cause skin infections and M types associated with skin infections rarely cause pharyngitis

A

T

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5
Q

T/F A few skin strains are associated with GN but many more pharyngeal strains are considered nephritogenic

A

F, More skin strains are associated nephritogenic

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6
Q

T/F Humans are the natural reservoir for GAS

A

T

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7
Q

Thie incidence of pharyngeal infection with GAS is highest in what age group

A

5-15 yrs of age, especially in young school-age

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8
Q

Incubation period for strep pharyngitis

A

2-5 days

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9
Q

Food containing GAS occasionally cause explosive outbreaks of

A

Tonsillopharyngitis

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10
Q

Children with GAS URTI are usually no longer infectious ___ hrs after appropriate antibiotic therapy has been started

A

24

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11
Q

___ and ___ can harbor GAS and play a role in disseminating impetigo

A

Fingernails and perianal region

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12
Q

Risk factors for invasive GAS infection

A

1) DM 2) HIV 3) IV drug use 4) chronic pulmonary or cardiac disease

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13
Q

The portal of entry is unknown in almost ___% of cases of severe invasive GAS infection

A

50

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14
Q

Virulence of GAS depends primarily on

A

M protein

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15
Q

Strains rich in M protein are more virulent because

A

M protein resist phagocytosis in fresh human blood

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16
Q

Toxins responsible for the rash of scarlet fever

A

Streptococcal pyrogenic exotoxins A, B, and C / erythrogenic toxin

17
Q

T/F Strep exotoxins stimulate the formation of specific antitoxin antibodies that provide immunity against the scarlatiniform rash but not against other strep infections

A

T

18
Q

GAS can produce up to ___ different pyrogenic exotoxins, and repeat attacks of scarlet fever are possible

A

12

19
Q

Strep toxin associated with streptococcal TSS

A

Exotoxin A, B, and C

20
Q

MC infections caused by GAS involve what organ systems

A

1) Respiratory tract 2) Skin and soft tissues

21
Q

Rash of scarlet fever appears within ___ after onset of symptoms, although it may appear with the first signs of illness

A

24-48

22
Q

Rash of scarlet fever often begins where

A

Around the neck and spreads over the trunk and extremities

23
Q

T/F Rash of scarlet fever blanches on pressure

A

T

24
Q

After ___ days, the rash of scarlet fever begins to fade and is followed by desquamation

A

3-4

25
Q

Progression of desquamation of the rash of scarlet fever

A

Face progressing downward, resembling a mild sunburn