streptococci

Question 1

alpha vs beta hemolysis

Answer 1

alpha –> partial (greening) of agar

beta –> complete clearing of agar

Question 2

streptolysin O vs streptolysin S

Answer 2

O: oxygen labile (sensitive), beta hemolytic

S: oxygen stable, beta hemolytic

Question 3

how are streptococci placed into lancefield groups

Answer 3

classification of all beta hemolytic streptococci by group polysaccharide antigens in cell wall

Question 4

sort streptococcaeae into lancefield groups

Answer 4

Group A: pyogenes
Group B: agalactiae
Group D: enterococcus faecalis + faecium
Group G: dysgalactiae
Group F: anginosus

Question 5

two groups of streptococci that are PYR positive

Answer 5

Group D (enterococcus) and Group A (s. pyogenes)

Question 6

antimicrobial susceptibility of enterococcus and streptococci

Answer 6

streptococci

Question 7

M protein

Answer 7

used for host cell attachment and protects bacteria from phagocytosis

Question 8

capsule

Answer 8

prevent opsonized phagocytosis

Question 9

pili

Answer 9

help bacteria stick to human cells and form biofilms

Question 10

streptokinase

Answer 10

lysis of fibrin clots which allows strep to evade clots and free themselves

Question 11

hyaluronidase

Answer 11

degrades hyaluronic acid in connective tissue

Question 12

vaccine used to prevent diphtheria

Answer 12

DTaP and Tdap

Question 13

importance of detecting corynebacterium jeikeium in clinical specimen

Answer 13

it is an oppurtunistic pathogen, common HAI, and resistant to multiple antibiotics (penicillins, cephalosporins, macrolides)

Question 14

colony morphology of the arcanobacterium

Question 15

principle of reverse CAMP test

Answer 15

the reverse camp test is a method to differentiate Group B strep from other streptococci species

Question 16

bacteria associated with erysipeloid skin infections

Answer 16

erysipelothrix rhusiopathiae

Question 17

appropriate specimen for recovery of erysipelothrix

Answer 17

skin lesions

Question 18

pathogenesis of nocardiosis

Answer 18

can either be inhaled and cause pulmonary nocardiosis
OR
can be inoculated through wounds in the skin and cause cutaneous infections (madura foot)

Question 19

normal habitats of actinomyces and nocardia

Answer 19

found in soil and plants

Question 20

differntiate biochemically actinomyces from nocardia

Answer 20

actinomyces: catalate negative, nitrate reduction negative

nocardia: catalase positive, nitrate reduction positive

Question 21

pathogenesis of bacillus anthracis

Answer 21

exotoxins enter skin through contact or inhalation

Question 22

assess the methods used to prevent and control B anthracis infections

Answer 22

anthrax vaccine only necessary for high-risk individuals (military, lab workers, etc.)

Question 23

describe the characteristic skin lesion of anthrax

Answer 23

papule which will turn black (eschar + localized necrosis)

Question 24

compare mechanisms of action B antracis exotoxins

Answer 24

EF (edema) –> adenylate cyclase activity

LF (lethal) –> protease

PA (protective) –> binds to cellular receptor

Question 25

discuss use of B antracis as a biological weapon

Answer 25

organism does not need to be alive, can be spread through spores which will continue to germinate and reproduce

Question 26

distinguish the roles of sentinel and reference laboratories in the identification of B antracis

Answer 26

sentinel laboratory performs lab test to idenfity B antracis (gram stain), reference labortories perform confirmatory tests (Ab staining)

Question 27

series of key tests to rule of b anthracis

Answer 27

non hemolytic (standing colonies), gram (+), non motile, penicillin sensitive, confirm with Ab staining

Question 28

key laboratories characteristics of B anthracis to B cereus

Answer 28

B cereus is beta hemolytic and motile while B anthracis is non hemolytic and non motile

Question 29

contrast route of infection and disease symptoms resulting from B cereus infection and similar S.aureus

Answer 29

B. cereus is typically ingested (toxins are emetic and diarrheal) and cause food poisoning, spores S aureus is also ingested but through enterotoxins no spore formation