Stahylcoccus

Question 1

If gram positive and Cluster catalase positive, what bacteria genus is it?

Answer 1

Staphylococcus

Question 2

Staphylococcus Aureus

Answer 2

Gram-positive, non-fastidious, facultative coccus

Question 3

What is the leading cause of nosocomial infections?

Answer 3

S. Aureus

Question 4

Special epidemiology of S. aureus

Answer 4

Higher colonization in diabetics, HIV, and burn patients

Question 5

Predominant site for S. aureus

Answer 5

Anterior nare

Question 6

Unique characteristic of community MRSA

Answer 6

Produces PVL and sensitive to non-beta lactams

Question 7

S. Aureus capsule function

Answer 7

Inhibits chemotaxis/phagocytosis, promotes adherence to foreign bodies

Question 8

S. aureus peptidoglycan

Answer 8

Inhibits phagocytosis, low endotoxin-like activity

Question 9

S. Aureus teichoic acid

Answer 9

Regulates cationic concentration at cell membrane. Binds to Fn

Question 10

S. Aureus Protein A

Answer 10

Binds IgG. Inhibits opsonization, complement activation

Question 11

Enzymes that S. Aureus produces

Answer 11

Coagulase, catalase, hyaluronidase, lipase, nucleases

Question 12

Coagulase

Answer 12

Converts fibrinogen to fibrin

Question 13

Catalase

Answer 13

Removes hydrogen peroxide

Question 14

Hyaluronidase

Answer 14

Hydrolyzes hyaluronic acids. Aids in spreading the the infection

Question 15

Lipases

Answer 15

Hydrolyzes lipids

Question 16

Nucleases

Answer 16

Digest DNA/RNA. Aids in spreading infection

Question 17

Cytolytic toxins of S. aureus

Answer 17

Alpha, beta, delta, gamma, PVL

Question 18

Exfoliative toxins of S. aureus

Answer 18

A and B. Are sertine proteases that digests the anchors int eh stratum granulosum. Most prevelant in neonates. Made by 30-50% of strains

Question 19

Enteroteoxins (A-R) and TSST-1 in S. aureus

Answer 19

are superantigens that act systemically. Cause non-specific T cell response, so releases an excess of IL-1, TNF, IL-2

Question 20

S. Aureus action on Ig

Answer 20

Binds to the Fc portion, so improperly coats the bacteria, thus preventing proper opsonization and phagocytosis

Question 21

Impetigo

Answer 21

Typically sores with a honey brown crusting found on the face or limb. 80% cause by S. aureus. 20% caused by S. pyogenes

Question 22

Most common cause of Folliculutis/Furuncle

Answer 22

S. aureas

Question 23

Carbyncle

Answer 23

Furuncles deep into the subQ tissue. Pt may have chills and a fever. Usually on nape of neck, upper back, buttocks. Think S. aureus 1st

Question 24

Mastitis

Answer 24

Infection introduced into the ductal system via cracked nipples. Tender, fever, fatigue, may require drainage

Question 25

Infective Endocarditis

Answer 25

Destructive infection (typically S. aureus) that creates an abcess

Question 26

Pneumonia and S. aureus

Answer 26

2% of community and 20% of nosocomial cases. P-V leukocidins case destructive community pneumonia. PVL is in ALL community MRSAa. Causes tissue destruction, hemoptysis, and septic shock

Question 27

#1 cause of osteomyelitis

Answer 27

Typically spread via blood or extension from subQ infection. Children: usually long bones. Adults: usually vertebra.

Question 28

Top 2 causes of Septic arthritis

Answer 28

1. N. gonorrhoeae in sexually active group. 2. S. aureus

Question 29

Scalded Skin Syndrome

Answer 29

aka Ritter's Disease. ET-A/B break desmoglein-1 in desmosomes to cause skin separation. Abrupt perioral erythema. Can have large blisters with NO ORGANISM

Question 30

Bullous Impetigo

Answer 30

Localized form of SSSS. Erythema does not extend beyond the border of the blisters. Bacteria can be isolated from skin lesions

Question 31

Toxic Shock Syndrome

Answer 31

Entire skin including palm and soles desquamates. Marked red tongue. High fatality.

Question 32

TSST-1

Answer 32

90% of menstration cases of TSS and 50% of other TSS. Linked to tampon use. Optimum oxygen, pH, and nutrients

Question 33

Enterotoxin B

Answer 33

Causes 50% of non-menstration TSS

Question 34

Cause of Staph related food poisoning

Answer 34

Has heat resistant toxins

Question 35

Tx for Staph food poisoning

Answer 35

Replacement fluid

Question 36

Antibiotic associated enterocolitis

Answer 36

C. diff is common cause, S. aureus is also a common cause. Is after an overuse of braod spectrum antibiotic

Question 37

S. aureus in abcesses identification

Answer 37

Gram (+) coccus

Question 38

S. aureus in bacteremia ident

Answer 38

Culture in blood. Staining unrewarding

Question 39

S. aureus in SSSS ident

Answer 39

Check nasopharyngeal samples. Rarely in blister fluid

Question 40

S. aureus in TSS ident

Answer 40

Cocci in vaginal samples. Blood samples will be negative

Question 41

Blood agar and S. aureus

Answer 41

Golden yellow colonies

Question 42

Catalase Test

Answer 42

Staphylococcus series are catalase positive. Streph and Entero are catalase negative

Question 43

Mannitol-salt agar and S. aureus

Answer 43

Will turn plate yellow due to the decreased pH by fermintation

Question 44

Tellurite-Glycine Agar

Answer 44

Tellurium from S. aureus will turn it black

Question 45

Coagulase test

Answer 45

Positive test means S. aureus. All other staph are negative

Question 46

Staphylococcus epidermidis

Answer 46

CON (Coagulase negative staph).

Question 47

Virulence factors of S. epidermidis

Answer 47

Lacks protein A, alpha-toxin, coagulase. Often drug resistant. Teichoic acid. Slime.

Question 48

Slime's function in S. epidermidis

Answer 48

Facilitates adherence to catheters. Forms protective biofilm. Interferes with PMN phagocytosis

Question 49

S. epidermidis and disease

Answer 49

Major cause of IV device associated infections. Prostetics/ catheters/pt equipement and hospital surfaces.

Question 50

Blood agar and S. epidermidis

Answer 50

White, non-hemolytic colonies

Question 51

Mannitol and S. epidermidis

Answer 51

Does not reduce tellurite

Question 52

Staphylococcus Saprophyticus

Answer 52

Typical in UTIs in women (2nd fequent cause). Frequently drug resistant. Novobiocin-resistant**