Streptococcus pyogenes

Question 1

transmitted via

Answer 1

respiratory droplets or direct skin contact

Question 2

frequently infects

Answer 2

skin or nasopharynx

Question 3

reservoir

Answer 3

humans

Question 4

causes ___% of streptococcal disease

Answer 4

90

Question 5

causes diseases that are both ___ and ____

Answer 5

pyogenic, toxigenic

Question 6

gram + or -

Answer 6

+

Question 7

catalase + or -

Answer 7

-

Question 8

coagulase + or -

Answer 8

-

Question 9

penicillin resistant or sensitive

Answer 9

sensitive

Question 10

factors that inhibit host immunity

Answer 10

hyaluronic acid capsule
M protein

Question 11

adhesive/invasive factors

Answer 11

M protein
hyaluronidase

Question 12

exotoxins

Answer 12

cytolytic exotoxins : streptomycin O and S
pyrogenic exotoxins: SpeA and SpeB

Question 13

hyaluronic acid capsule

Answer 13

mimics the hyaluronic acid found in human connective tissue
hides the bacteria from phagocytes

Question 14

M protein

Answer 14

important adhesion
prevents opsonization by breaking down complement C3b

Question 15

Streptolycin O

Answer 15

lyses leukocytes and erythrocytes

Question 16

SpeA

Answer 16

super antigen that causes helper T cells to release a cytokine storm leading to toxic shock

Question 17

SpeB

Answer 17

protease that destroys tissue, leading to fluid accumulation in the areas of damage

Question 18

genes for Spe toxins are encoded by a

Answer 18

temperate bacteriophage and therefore only lysogenized S. pyogenes strains can synthesis these toxins

Question 19

lysogenic conversion

Answer 19

new host phenotype due to expressed genes from a phage

Question 20

Streptococcal pharyngitis

Answer 20

S. pyogenes is inhaled and bacteria replicate in mucosa of the pharynx
- patches of pus on tonsils, in back of throat
- tonsil may be swollen , red and tender
- fever
- absence of cough and nasal discharge
- most common in 5-10 year old children

Question 21

impetigo

Answer 21

enters through skin that is already irritated or raw
small, flattened, red patches that develop into pustules that eventually rupture and crust over with a honey colored crust
- highly contagious

Question 22

cellulitis

Answer 22

spreads to the deeper dermis and subcutaneous tissues
- red puffy patches with ill-defined edges
- fever, cells, leukocytosis
- occurs in middle aged and elderly

Question 23

necrotizing fasciitis

Answer 23

caused by highly virulent strains that produce SpeA and SpeB as well as other enzymes such as streptomycin O
- infects a wound
- the enzymes and toxins allow the bacteria to invade and destroy muscle, fat and organ fascia
- pain level inconsistent with the severity of the original injury

Question 24

streptococcal toxic-shock syndrome

Answer 24

caused by streptococcal pyrogenic exotoxin (SpeA and B) and additional virulence factors
less common but more deadly than staphylococcal TSS

Question 25

symptoms of streptococcal toxic-shock syndrome

Answer 25

high fever
diffuse sunburn-like rash
hypotension
shock
multi organ failure
BUT MAY INCLUDE NECROTIZING FASCIITIS