chapter 4 streptococci Flashcards
Group A beta-hemolytic streptococci also called which means
what diseases do they cause
also called streptococcus pyogenes
pus producing
-diseases: strep throat scarlet fever rhematic fever post-strep glomerulnephritis
Strep cell wall: C carb
divides strep into lancefield groups
strep cell wall M protein
major virulence factor for group A
-inhibits complement and protects organism from phagocytosis
-weakest pt bc B cells generate Abs against it for opsonization
Beta-hemolytic group A strep have enzymes that contribute to their pathogenicity
streptolysin O (oxygen liable): destorys RBCs, antigenic, ASO Abs develop after exposure
streptolysin S (oxygen stabile): responsible for beta-hemolysis but not antigenic
pyrogenic exotoxin (erythrogenic toxin) -only a few strains this group but can cause scarlet fever
streptokinase: activates plasmin to break up firbrin clots
hyaluronidase, DNAases, anti-C5apeptidase
beta hemolytic gropu A streptococci cause 4 types of disease by local invasion and or exotoxin release
streptococcal pharyngitis
streptococcal skin infections
scarlet fever
streptococcal toxic shock syndrome
beta-hemolytic group A can also cause 2 delayed antibody mediated diseases
rheumatic fever
glomerulonephritis
rapid antigen detection test should be done when
exudative pharyngitis (pus on tonsils)
skin infections from strep can be similar to _____ so treatment of these infections should be ____which covers both gropus
staph aureus
dicloxacillin
erysipelas is a
strep infection of superficial skin, dermis only
-raised, bright red rash with sharp border that advances from initial site of infection
pyoderma
pustule, usually on extremeity or face that breaks down after 4-6 days to form a thick crust
necrotizing fasciitis organisms can cause it
group A beta-hemolytic streptococcal infection
stahylococcus
clostridium
necrotizing fasciitis clinically
mortality rate
travels along fascia
1 day: swelling, heat, redness
2 days: skin color from red to purple to blue and large blisters
later: skin dies and muslce may become infected
-50% mortality rate
fournier’s gangrene and orgnaism often involved
necrotizing faciitis involving male genital area and perineum
-strep pyogenes
scarlet fever
-organism
toxin
symptoms
certain beta-hemolytic group A strep
-pyrogenic toxin or erythrogenic toxin
produces fever and causes a scarlet red rash
-on trunk and neck then goes to extremities sparing the face
rheumatic fever usually strikes children how old
5-15
6 major manifestations of rheumatic fever
fever myocarditis joint swelling chorea (uncontrolled dance movements of extremities) subcutaneous nodules rash (erythema marginatum
acute post streptococcal glomerulonephritis clinically
Ab mediated inflammatory disease of glomeruli of kidney
occurs about 1 week after infection of pharynx or skin by nephritogenic strains beta hem group A
- child will have puffy face, urine darker than normal, possibly hypervolemia and high BP
- good prognosis espceially in pediatric population
group B streptococci also called
class
streptococcus agalactiae
beta hemolytic
group B strep clinically
25% of women carry these bugs vaginally and baby can acquire these bacteria during delivery
-cause neonatal meningitis, pneumonia, sepsis
neonates with meningitis from group B strep present
no stiff neck
fever, vomiting, poor feeding, irritability
3 most common pathogens associated with meningitis in infants younger than 3 months of age
E coli
listeria monocytogenes
group B strep
two bacteria that cause meningitis later in life after moms Abs are gone and before new Abs develop in baby
neisseria meningitides
haemophilus influenzae
viridans strep cause 3 main types of infection
dental infections
endocarditis
abscesses
dental infections, some of the viridans escpecially ____ can bind to teeth and ferment sugar which produces acid and dental cavities
S mutans
