Stahylcoccus Flashcards

1
Q

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

A

Staphylococcus

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2
Q

Staphylococcus Aureus

A

Gram-positive, non-fastidious, facultative coccus

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3
Q

What is the leading cause of nosocomial infections?

A

S. Aureus

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4
Q

Special epidemiology of S. aureus

A

Higher colonization in diabetics, HIV, and burn patients

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5
Q

Predominant site for S. aureus

A

Anterior nare

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6
Q

Unique characteristic of community MRSA

A

Produces PVL and sensitive to non-beta lactams

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7
Q

S. Aureus capsule function

A

Inhibits chemotaxis/phagocytosis, promotes adherence to foreign bodies

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8
Q

S. aureus peptidoglycan

A

Inhibits phagocytosis, low endotoxin-like activity

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9
Q

S. Aureus teichoic acid

A

Regulates cationic concentration at cell membrane. Binds to Fn

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10
Q

S. Aureus Protein A

A

Binds IgG. Inhibits opsonization, complement activation

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11
Q

Enzymes that S. Aureus produces

A

Coagulase, catalase, hyaluronidase, lipase, nucleases

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12
Q

Coagulase

A

Converts fibrinogen to fibrin

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13
Q

Catalase

A

Removes hydrogen peroxide

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14
Q

Hyaluronidase

A

Hydrolyzes hyaluronic acids. Aids in spreading the the infection

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15
Q

Lipases

A

Hydrolyzes lipids

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16
Q

Nucleases

A

Digest DNA/RNA. Aids in spreading infection

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17
Q

Cytolytic toxins of S. aureus

A

Alpha, beta, delta, gamma, PVL

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18
Q

Exfoliative toxins of S. aureus

A

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

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19
Q

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

A

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

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20
Q

S. Aureus action on Ig

A

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

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21
Q

Impetigo

A

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

22
Q

Most common cause of Folliculutis/Furuncle

A

S. aureas

23
Q

Carbyncle

A

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

24
Q

Mastitis

A

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

25
Q

Infective Endocarditis

A

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

26
Q

Pneumonia and S. aureus

A

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

27
Q

1 cause of osteomyelitis

A

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

28
Q

Top 2 causes of Septic arthritis

A
  1. N. gonorrhoeae in sexually active group. 2. S. aureus
29
Q

Scalded Skin Syndrome

A

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

30
Q

Bullous Impetigo

A

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

31
Q

Toxic Shock Syndrome

A

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

32
Q

TSST-1

A

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

33
Q

Enterotoxin B

A

Causes 50% of non-menstration TSS

34
Q

Cause of Staph related food poisoning

A

Has heat resistant toxins

35
Q

Tx for Staph food poisoning

A

Replacement fluid

36
Q

Antibiotic associated enterocolitis

A

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

37
Q

S. aureus in abcesses identification

A

Gram (+) coccus

38
Q

S. aureus in bacteremia ident

A

Culture in blood. Staining unrewarding

39
Q

S. aureus in SSSS ident

A

Check nasopharyngeal samples. Rarely in blister fluid

40
Q

S. aureus in TSS ident

A

Cocci in vaginal samples. Blood samples will be negative

41
Q

Blood agar and S. aureus

A

Golden yellow colonies

42
Q

Catalase Test

A

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

43
Q

Mannitol-salt agar and S. aureus

A

Will turn plate yellow due to the decreased pH by fermintation

44
Q

Tellurite-Glycine Agar

A

Tellurium from S. aureus will turn it black

45
Q

Coagulase test

A

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

46
Q

Staphylococcus epidermidis

A

CON (Coagulase negative staph).

47
Q

Virulence factors of S. epidermidis

A

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

48
Q

Slime’s function in S. epidermidis

A

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

49
Q

S. epidermidis and disease

A

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

50
Q

Blood agar and S. epidermidis

A

White, non-hemolytic colonies

51
Q

Mannitol and S. epidermidis

A

Does not reduce tellurite

52
Q

Staphylococcus Saprophyticus

A

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