streptococcus

Question 1

process of identify strep

Answer 1

1) hemolysis
2) if beta-hemolysis, test for carbohydrate A-O with exception of D
3) if A, check M protein 1-90

Question 2

strep group A known as:

Answer 2

S. pyogenes

Question 3

appearance of gamma hemolysis

Answer 3

nothing

Question 4

appearance of alpha hemolysis

Answer 4

• cloudy green due to remaining intact RBCs with altered green heme pigment

Question 5

appearance of beta hemolysis

Answer 5

• clear, fully lysis of RBCs

Question 6

S. pyogenes, where found?

Answer 6

skin, oropharynx

Question 7

S. pyogenes extracellular proteins for bacterial proliferation

Answer 7

• streptolysins - lyse red cells, cause beta-hemolysis, O is oxygen labile, antigenic, leads to ASO antibody titers important in lab diagnosis, S is poorly antigenic and oxygen stable
• streptokinase - proteolysis, destroys fibrin clots
• DNAase

Question 8

S. pyogenes antiphagocytic elements

Answer 8

• hyaluronic acid capsule

- M-proteins, strains with large amount of M-protein are more resistant to phagocytosis

Question 9

what does Spe stand for?

Answer 9

streptococcal pyrogenic extoxin

Question 10

what is caused by SpeA, B, and/or C?

Answer 10

• rash of scarlet fever

- strep toxic shock syndrome

Question 11

what are the S. pyogenes toxin-mediated diseases?

Answer 11

• scarlet fever

- strep toxic shock syndrome

Question 12

characteristics of strep toxic shock syndrome

Answer 12

• severe hypotension
• two or more of following: impaired renal function, DIC, impaired liver function, resp distress, rash, soft tissue necrosis

Question 13

S. pyogenes invasive syndromes

Answer 13

• puerperal fever - uncommon in developed countries, infection of uterus immediately after childbirth
• acute pharyngitis/tonsilitis (strep throat)
• impetigo - mild child superficial skin infection
• erysipelas - severe cellulitis of dermis and underlying tissue
• necrotizing fasciitis - flesh-eating bacteria disease

Question 14

what is a good test to narrow strep down to group A?

Answer 14

if it is sensitive to bacitracin, other groups are resistant

Question 15

2 sequelae of S. pyogenes

Answer 15

• rheumatic fever - 2-3 weeks after sore throat, antibodies react with antigens on heart etc.
• acute glomerulonephritis - immune complexes deposit that contain bacterial antigens

Question 16

test for recent S. pyogenes infection

Answer 16

• titer of 160 or greater for antibody to streptolysin O or four-fold increase in ASO titer

Question 17

S. pyogenes treatment

Answer 17

PENICILLIN - no resistance to penicillin recorded

Question 18

most important species of group B strep

Answer 18

S. agalactiae

Question 19

S. agalactiae, where found?

Answer 19

vagina, colon

Question 20

major disease from S. agalactiae

Answer 20

1/3 of neonatal infections - septicemia, meningitis, pneumonia, death

Question 21

two epidemiological patterns of S. agalactiae

Answer 21

• early onset - vaginal during birth, penicillin or ampicillin
• late onset - infant to infant spread within nursery

Question 22

group D strep are known as:

Answer 22

enterococci

Question 23

entercocci, where found?

Answer 23

common inhabitants of GI tract

Question 24

common diseases from enterococci

Answer 24

UTI, wound infections, sepsis

Question 25

enterococci treatment

Answer 25

- resistant to many antibiotics | - vancomycin is last resort

Question 26

most important enterococci species

Answer 26

- E. faecalis | - E. faecium

Question 27

viridans streptococci hemolysis?

Answer 27

alpha hemolysis

Question 28

most common viridans streptococci species:

Answer 28

- S. mutans | - S. sanguis

Question 29

viridans streptococci, where found?

Answer 29

mouth, nose, pharynx

Question 30

diseases caused by viridans streptococci

Answer 30

- frequent cause of INFECTIVE ENDOCARDITIS, often fatal when untreated

Question 31

streptococcus pneumoniae known as:

Answer 31

pneumococcus

Question 32

pneumococcus gram stain and shape

Answer 32

diplococci, lancet shaped, gram positive

Question 33

pneumococcus pathogenesis

Answer 33

- pneumococcal capsule hinders phagocytosis - IgA protease degrades surface IgA on respiratory epithelium - pneumolysin, lytic enzyme contributes to pathogenesis

Question 34

pneumococcus disease

Answer 34

- most frequent cause of bacterial pneumonia (cough, fever, chills, lung pain, rusty sputum, leukocytosis, - meningitis - otitis

Question 35

who are at high risk for pneumococcal pneumonia?

Answer 35

- immunocompromised - splenectomy - sickle cell anemia