Staphloccoci

Question 0

Staph. Aureus is coagulase _____

Answer 0

Positive.

Staph aureus is the only coagulase POSITIVE staph (that we have to know)

Coagulase positive = will clot plasma by activating fibrinogen

Question 1

All three important groups of staphloccoci are GM ____ with _____ morphology

Answer 1

GM + cocci in grape clusters

Question 2

Staph epidermidis is coagulase _____

Answer 2

Negative; it will not clot plasma

Question 3

Staph saprophyticus is coagulase _____

Answer 3

negative. it will not clot plasma

Question 4

All staphloccoci are Catalase ______, allowing us to differentiate them from ______ species

Answer 4

Staph are catalase POSITIVE; this allows us to distinguish them from catalase negative STREPTOCOCCI

Question 5

Staphlococci are _________ an/aerobes

Answer 5

FACULATIVE ANAEROBES

Question 6

Colony colors:

S. Aureus
S. Epidermidis
S. Saprophyticus

Answer 6

yellow
white
white

Question 7

Of the 3 major staph species, which is RESISTANT TO NOVOBIOCIN?

Answer 7

S. Saprophyticus

Question 8

Which staph species(s) is positive for PROTEIN A?

Answer 8

S. Aureus

Question 9

Which staph species(s) is positive for teichoic acid

Answer 9

ALL 3

Question 10

T/F: S. Aureus is a toxin producer, and an invasive opportunistic pathogen

Answer 10

TRUE

Question 11

Which staph species(s) is DNAse positive

Answer 11

Just S. Aureus

Question 12

Which staph species(s) is hemolytic on blood agar?

Answer 12

Just staph aureus

Question 13

T/F: S. Aureus is more likely to colonize the hospitalized and those with foreign bodies

Answer 13

True

Question 14

Name 3 toxin-mediated diseases by S. Aureus:

Answer 14

1. food borne diarrhea - enterotoxin contamination, bacteria not present
2. toxic shock syndrome - toxin production after bacterial colonization via fibrinogen receptor-ligand interacctions
3. Staphlococcal scalded skin syndrome - caused by exfolatins

Question 15

What toxins and enzymes are responsble for cell lysis by S. Aureus? (there are 7, but 2 important ones)

Answer 15

ALPHA TOXIN - lyse cell membrane
COAGULASE - forms clots in plasma
leukocidins
proteases
hyalaronidase 
lipase
staphlokinase

Question 16

What is the function of S. Aureus’ ‘Protein A’?

Answer 16

PROTEIN A is a cell wall protein that binds hist IgG via FcR, which results in less complement mediated killing. Also, it is a B cell superantigen leading to defective IgM production. OVERALL, IT AIDS IN IMMUNE EVASION

Question 17

What are the functions of S. Aureus enterotoxins A-E, G, H, and I?

Answer 17

These are T cell superantigens allowing S AUREUS TO BLUNT THE HOST T CELL IMMUNE RESPONSE

Question 18

Function of S. Aureus capsular polysaccharides?

Answer 18

Anti-phagocytic

Question 19

T/F: S. Aureus enterotoxin is HEAT STABLE

Answer 19

TRUE; boiling will not destroy this toxin. (thus you get food poinsining)

Question 20

T/F: S. Aureus enterotoxins can act as superantigens

Answer 20

True, types A and C are superantigens

Question 21

T//F: S. Aurues toxic shock syndrome does not require colonization

Answer 21

False - Colonization must occur for TSS

Question 22

TSST-1 is a _____________ associated with ______ syndrome which can result from _____ use or _______

Answer 22

TSST-1 is a superantigen
it is produced during toxic shock syndrome
TSS can occur from tampon use or wound infection

Question 23

SSSS is caused by:

Answer 23

Staphlococcal scalded skin syndrome is cause by toxins called EXFOLIATINS A and B

Question 24

T/F: the genes for exofolitins A and B are encoded on all S. Aureus DNA.

Answer 24

False, these toxins are encoded only in certain strains (PHAGE GROUP II) and are located on the ETA PLASMID

Question 25

T/F: exofolitins are superantigens

Answer 25

TRUE

Question 26

T/F: the sites of peeling in SSSS are indicative of local exofoliatin production

Answer 26

FALSE. the site of exfoliation may not be the site where the toxin is being produced

Question 27

Invasive diseases caused by Staph Aureus, unlike toxin mediated diseases, are characterized by :

Answer 27

Suppuration and ABSCESS formation

Question 28

What is the last resort drug for Staph Aureus strains that are resistant to _____ and _____

Answer 28

The last resort drug is VANCOMYCIN, used for strains that are resistant to synthetic penicillins like DICLOXACIN and OXACILLIN

Question 29

Staphlococcus epidermidis is a coagulase ____, GM ____ coccus.

Answer 29

Coagulase negative, GM +

Question 30

Staphylococcus epidermidis is catalase ______

Answer 30

Catalase positive, this enables it to be differentiated from Group A Streptococci.

Question 31

T/F: Staph Epidermidis is sensitive to Novobiocin

Answer 31

True

Question 32

Staph epidermidis is part of the normal skin flora yet is an opportunistic pathogen. What is its major mechanism of invasion, and who is most at risk?

Answer 32

Staph epidermidis infections are primarily transmitted by ahderence to FOREIGN BODIES such as catheters, lines, prostheses, etc; thus it is most common in neonates, renal failure pts, immunocompromised.

Question 33

T/F: Staph Epidermidis cannot form biofilms

Answer 33

False, S. Epidermidis CAN form biofilms, an does so on prosthetic surfaces efficiently.

Question 34

T/F: Staph Aureus bacteremia is more toxic than Staph Epidermidis bacteremia

Answer 34

TRUE

Question 35

Staphylococcus Saprophyticus is coagulase _____

Answer 35

Negative

Question 36

Staph Saprophyticus is ______ to Novobiocin

Answer 36

RESISTANT (unlike S. Epidermidis)

Question 37

T/F: Staph Saprophyticus is a skin commensal

Answer 37

TRUE

Question 38

A common clincal syndrome of staph saprophytics is:

Answer 38

Female UTI w/ polyuria + dysuria

Question 39

How do you treat a female with a S. Saprophyticus UTI?

Answer 39

``` Trimethoprim sulfamethoxazol (bactrim) norfloxacin (a quinolone) ``` These durgs have good bladder penetration