MIDTERM 2 - Streptococcus

Question 1

= gram (+) cocci
= arranged in pairs or in chains
= catalase negative

Answer 1

Genus Streptococcus

Question 2

very small zone of NO HEMOLYSIS and then a wider zone of β-hemolysis; mistaken as β hemolysis at first glance

Answer 2

Hemolytic pattern on sheep’s blood agar

Question 2

= fastidious; grown in enriched media
= most are facultative anaerobes
= non-motile but would just grow along the stab line or
along the line of inoculation

Answer 2

Genus Streptococcus

Question 2

classic strep throat; red swollen tonsils and pharynx; a purulent exudate on tonsils, fever,
swollen lymph nodes that usually lasts 5 days

Answer 2

Streptococcal pharyngitis

Question 2

also known as Wide Zone

Answer 2

Alpha-Prime (α’)

Question 2

type of infection, site of origin

Answer 2

Physiologic characteristics

Question 2

enzyme destroys RBC & WBC and is the reason for beta-hemolytic ability

Answer 2

Streptolysin O

Question 3

Lancefield antigens are given letter names_____________
through S.

Answer 3

A, B, C, D, E,

Question 3

In Streptolysin S, S stands for _____

Answer 3

oxygen stabile

Question 3

C carbohydrate present or extracted from the cell wall

Answer 3

Lancefield classification

Question 3

antigen causing increased ASO titer

Answer 3

Streptolysin O

Question 3

also responsible for beta-hemolysis but is not antigenic

Answer 3

Streptolysin S

Question 3

more than 30 species of streptococci, only 5 are
significant human pathogens; Three of these pathogens have Lancefield antigens: Lancefeld group ___________

Answer 3

Lancefeld group A, B and D

Question 3

major virulence factor for group A streptococcus. It inhibits the activation of complement and protects from phagocytosis; However, it is also the weakest point in the organism’s defense

Answer 3

M protein

Question 3

pus-producing; strep throat, scarlet fever, rheumatic fever, & post-streptococcal
glomerulonephritis

Answer 3

Group A Beta-hemolytic Strep

Question 3

cause scarlet fever; causes streptococcal toxic shock syndrome

Answer 3

Pyrogenic exotoxin | erythrogenic toxin

Question 3

In Streptolysin O, O stands for _______ as it is inactivated by oxygen

Answer 3

oxygen labile

Question 3

flesh eating strep; break in skin caused by trauma then follow a
path along fascia; patient develops swelling, heat, & redness that moves rapidly from initial infection site; day later skin changes from red to purple to blue, & large blisters form; later skin dies & muscle become infected

Answer 3

Necrotizing Fasciitis

Question 3

produced pyrogenic toxin or erythrogenic toxin; fever, sorethroat & scarlet-red rash; rash begins on trunk and neck then spreads to extremities, sparing the face; strawberry tongue

Answer 3

Scarlet fever

Question 3

Streptolysin S, S stands for _____

Answer 3

oxygen stabile

Question 3

also responsible for beta-hemolysis but is not antigenic

Answer 3

Streptolysin S

Question 3

infection of the dermis; raised, bright red rash with sharp
border

Answer 3

Erysipelas

Question 3

similar to scarlet fever, also mediated by the release of pyrogenic toxin; signs and symptoms are similar with staph TSS

Answer 3

Streptococcal toxic shock syndrome

Question 3

affects children 5-15 years of age; follows untreated streptococcal pharyngitis
NOT after a skin infection

Answer 3

Rheumatic fever

Question 4

antibody-mediated inflammatory disease of glomeruli; occurs 1 week after infection of either pharynx OR skin by nephritogenic strains of S. pyogenes.

Answer 4

Acute post-streptococcal glomerulonephritis

Question 4

normal flora of lower GIT; beta-hemolytic; 25% of women carry it vaginally which a baby can acquire during delivery causes neonatal (< 3 months of age) meningitis, pneumonia, sepsis

Answer 4

Group B Strep

Question 4

occur first 3 days after birth (usually within 24 hours); commonly associated with obstetric complications and premature birth; causes neonatal pneumonia

Answer 4

Early – onset Infection

Question 4

occurs between 1 week and 3 months after birth; causes neonatal meningitis; uncommonly associated with obstetric complications; organism is rarely found in the mother’s vagina prior to birth

Answer 4

Late – onset Infection

Question 4

important virulence factor; prevents phagocytosis; ineffective after opsonization

Answer 4

Capsule

Question 4

the most significant component of the capsule

Answer 4

Sialic acid

Question 4

Loss of Sialic acid = ______

Answer 4

loss of virulence

Question 4

major cause of bacterial pneumonia & meningitis in
adults; otitis media in children

appear as lancet-shaped, gram-positive cocci arranged in pairs (diplococci)

major virulence factor is its capsule

Answer 4

Pneumococcus

Question 4

most of viridans streptococci are _______

Answer 4

alpha-hemolytic

Question 4

S. mutans bind to teeth & ferment sugar producing acid and dental caries

Answer 4

Dental infections

Question 4

Dental manipulations spreads organisms into the bloodstream then implants the heart, results in subacute bacterial endocarditis (SBE)

Answer 4

Endocarditis

Question 5

normal flora of intestines; alpha hemolytic; urinary tract infections, biliary tract infections; one of the most common cause of nosocomial
infections

Answer 5

Enterococcus (S. faecalis, S. faecium)

Question 5

association between S. bovis infection and colon cancer; 50% of people with S. bovis bacteremia have a colonic malignancy

Answer 5

Group D Strep (S. bovis, S. equinus)

Question 5

normal flora of G.I. tract, nasopharynx and
gingival crevices

Answer 5

Viridan Group Streptococci