Unit 3: Cocci Flashcards Preview

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Flashcards in Unit 3: Cocci Deck (29)
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1

When bacteria are plated onto blood agar, how do alpha, beta, and gamma colonies appear?

alpha - dark green (incomplete blood lysis)beta - clear colony (complete lysis)gamma - no change (non-hemolytic)

2

How do you tell if a bacteria is catalase positive?

Drop hydrogen peroxide and fizzing will occur

3

Lancefield typing is based on what bacterial feature?

carbohydrate composition of bacterial cell walls

4

When bacterial growth is inhibited by bacitracin antibiotic (Bacitracin Testing), what does it indicate?

The culture is streptococcus pyogenes (Group A is bacitracin sensitive!)

5

Describe what a positive CAMP test indicates

Group B strep

6

What cocci are gram positive and which are gram negative?

Gram positive: staphylococcus and streptococcus
Grame negative: Neisseria

7

How do you differentiate staphylococcus from streptococcus if they're both gram positive?

Staphylococcus is catalase positive
Streptococcus is catalase negative

8

What are the 3 kinds of Staph? How do you differentiate the 3?

Staph aureus, staph epidermis, s. saprophyticus

S. aureus is coagulase positive, create gold colonies, beta hemolytic and susceptible to bacteriophages whereas the other 2 are coagulase negative and non hemolytic (gamma).

9

What are the two alpha hemolytic streptococcus

strep pneumoniae and strep viridans

10

What are the two beta hemolytic streptococcus

strep pyogenes (group A)
strep agalactiae (group B)

11

What differentiates Streptococcus group A from Group B?

Strep Group A (pyogenes) is bacitracin sensitive
Strep Group B (agalactiae) is bacitracin resistant

12

What are the gamma hemolytic streptococcus

Strep fecalis (enterococcus fecalis / Group D) Peptostreptococcus

13

What differentiates N. meningitides from N. gonorrhoeae?

N. meningitides has CAPSULE, ferments MALTOSE on chocolate agar

N. gonorrhoeae has NO CAPSULE, NO MALTOSE

They do share these characteristics: gram negative, diplococci, oxidase positive

14

What shape does streptococci take on under microscope?

Chain of circles

15

What shape does staphylococcus take on?

clusters of circles

16

How does neisseria appear under microscope?

diplococci

17

What bacteria has pili, releases several pyrogenic toxins, has streptolysin O (very antigenic), is penicillin and erythromycin sensitive. Located in pharynx and skin?

Group A Streptococci Strep pyogenes

18

This bacteria is bacitracin resistant, has a capsule, located in genital tract and transmitted at birth. What is it and what should be given to a pregnant woman during delivery to prevent infection?

Group B Strep (strep agalactiae)

Must give penicillin 18 hours after rupture of membranes if labor hasn't started to prevent ascending infection of uterus

19

This is a gram positive, alpha hemolytic diplococci that has a polysaccharide capsule, usually resides in the throat and is becoming more penicillin resistant

Strep pneumonia

20

This resides in the normal flora of the colon, causes abdominal abscesses, UTIs, endocarditis, and is sometimes penicillin resistant (use aminoglycosides)

Enterococcus fecalis
Streptococcus fecalis

21

This resides in the mouth and female genital tract, has extracellular polysaccharides, and alpha hemolytic and gram positive

Strep viridans

22

Found in mouth flora, respiratory tract, female genital tract and bowel. Found in abcesses with complex mix of organisms (not the primary pathogen). Non hemolytic

Peptostreptococcus

23

What do you use to treat MRSA?

Vancomycin

24

Found in the nose and skin. Transmitted by direct contact or indirect fomite contact. Has a Protein a, Capsule and several toxins. Resistant to penicillin and methicillin

Staph aureus

25

Normally found in skin and mucous membrane, but attaches to nylon and plastic, infecting IVs, and antibiotics don't eliminate the infection. Catalase positive and coagulase negative.

Staph epidermis

26

Usually causes UTIs, catalase positive, coagulase negative, nonhemolytic

Staph saprophyticus

27

There exists a vaccine and can be treated with penicillin. Carried in respiratory tract. Endotoxin in membrane and has capsule

Neisseria meningitides

28

Has no capsule, has a pili, found inside neutrophils , sexual or neonatal transmission. Treated with ceftriaxone and doxycycline (penicillin resistant)

N. gonorrhoeae

29

If someone has a lesion that is sterile when swabbed, has rheumatic fever, chorea, or nephritis, what type of bacterial infection might they have had and recovered from prior to these new conditions?

Streptococcal infection