Bacteriology Primer - IDBR

Question 1

What are the gram positive catalase positive organisms? [3]

Answer 1

Coag + and negative staph
Micrococcus
Kocuria

Question 2

What are the gram positive catalase negative organisms? [2]

Answer 2

Enterococcus and strep

Question 3

Which gram positive organisms are beta hemolytic on blood agar? [3]

Answer 3

Staphylococcus aureus
Streptococcus pyogenes
Groups B, C, F, G Streptococci

Question 4

What gram positive organisms are PYR positive? [2]

Answer 4

Enterococcus species

Streptococcus pyogenes

Question 5

Is staph aureus hemolytic?

Answer 5

Yes - Beta hemolytic

Question 6

What gram positive organisms are alpha/gamma hemolytic? [3]

Answer 6

Enterococcus species
Viridans Streptococcus species
Streptococcus pneumoniae [alpha alone]

Question 7

What gram positive organisms are beta hemolytic? [3]

Answer 7

Staphylococcus aureus
Streptococcus pyogenes
Groups B, C, F, G Streptococci

Question 8

Gram stain shows gram positive cocci in clusters which is coagulase positive and beta hemolytic. Diagnosis

Answer 8

Staph aureus

Question 9

Gram stain shows gram positive cocci in clusters which is coagulase negative. Diagnosis? [3]

Answer 9

Coag negative staph
Micrococcus species
Kocuria species

Question 10

Gram stain shows gram + cocci in pairs and short chains. Ddx? [3]

Answer 10

Enterococcus species
Streptococcus pyogenes
Strep pneumo

Question 11

Gram stain shows gram + cocci in pairs and long chains. Ddx? [2]

Answer 11

Groups B, C, F, G Streptococci

Viridans Streptococcus species

Question 12

What is lancefield group A strep?

Answer 12

S. pyogenes

Question 13

What is lancefield group B strep?

Answer 13

S. agalactiae

Question 14

What is lancefield group C strep?

Answer 14

S. dysgalactiae subsp. dysgalactiae

Question 15

What is lancfield group C, G, (A, L) strep?

Answer 15

S. dysgalactiae subsp. equisimilis

Question 16

What is lance field group A, C, G, F strep?

Answer 16

S. anginosus group

Question 17

What is lance field group E, P, U, V strep?

Answer 17

S. porcinus

Question 18

Gram stain shows gram + cocci in pairs and short chains. PYR +, α‐ or ɣhemolytic. Dx?

Answer 18

Enterococcus

Question 19

Gram stain shows gram + cocci in pairs and short chains. PYR +, Beta hemolytic. Dx?

Answer 19

Streptococcus pyogenes

Question 20

Gram stain shows gram + cocci in pairs and short chains. PYR -, alpha hemolytic. Dx?

Answer 20

Streptococcus pneumoniae

Question 21

Gram stain shows gram + cocci in long chains, Catalase (‐), α‐ or ɣ‐ hemolytic. Dx?

Answer 21

Viridans Streptococcus

Question 22

Gram stain shows gram + cocci in long chains, Catalase (‐), beta hemolytic. Dx?

Answer 22

Groups B, C, F, G Streptococci

Question 23

What determines lance field groups?

Answer 23

Teichoic acid antigen.

Question 24

What do gram positive cocci in tetrads indicate on gram stain?

Answer 24

coagulase negative staphylococci or Micrococcus species

Question 25

What is the only PYR positive strep species?

Answer 25

Strep pyogenes

Question 26

Abiotrophia/Granulicatella require what to grow?

Answer 26

pyridoxal or cysteine

Question 27

What agar do Abiotrophia/Granulicatella grow on?

Answer 27

Chocolate agar

Question 28

What group is strep pneumonia a member of?

Answer 28

Streptococcus mitis

Question 29

What type of colonies do strep pneumonia form?

Answer 29

Donut shaped, raised edges, indented center

Question 30

What is the difference between Beta, alpha, and gamma hemolysis?

Answer 30

Beta - completely lyse RBCs leaving a clear zone of hemolysis around the colony Alpha - incompletely lyse RBCs leaving greenish discoloration of the culture medium surrounding the colony Gamma hemolytic - Do NOT hemolyze, AKA non-hemolytic

Question 31

What is the significance of optochin sensitivity?

Answer 31

Both Strep pneumonia and Strep viridian's is alpha hemolytic. To differentiate this a disc inoculated with optochin is placed on the plate. Strep pneumonia is inhibited Strep viridans will grow

Question 32

What 5 groups of strep make up the virdans group?

Answer 32

mutans, anginosus (milleri), mitis, salivarius, bovis --> Each group has multiple species in it.