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BACT211 (LECTURE) > WEEK 4: STAPHYLOCOCCI > Flashcards

WEEK 4: STAPHYLOCOCCI Flashcards

1
Q

Peptidoglycan Layer: Multilayered
Teichoic acids: Present in many
Periplasmic Space: Absent
Outer Membrane: Absent
LPS Content: Virtually none
Lipid & Lipoprotein: Low

A

Gram positive

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2
Q

Peptidoglycan Layer: Single layered
Teichoic acids: Absent
Periplasmic Space: Present
Outer Membrane: Present
LPS Content: High
Lipid & Lipoprotein: High

A

Gram negative

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3
Q

i. Gram (+) cocci arranged in tetrads
or clusters
i. Facultative anaerobes
ii. Catalase positive
iii. Oxidase Negative
iv. Non-motile, non-spore-forming glucose
fermenters
v. Grows in 7.5-10% NaCl
vi. Small-colony variants- rare strain,
fastidious, req. CO2, hemin for growth.

A

Staphylococci

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4
Q

What are the organisms that are positive in catalase test?

A

Staphylococcus & Micrococcus

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5
Q

What is the test that will differentiate micrococcus to staphylococcus?

  • Test for the position of Cytochrome to
    produce a dark-blue end product when
    reacted with the Reagent.
A

Microdase test or Modified Oxidase Test

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6
Q

▪ Most clinically significant specie of Staphylococci
▪ Present in various skin surfaces and nares
▪ It causes infection when it enters a normally sterile site
▪ Cause of nosocomial or hospital-acquired infections
▪ It is also one of the common causes of food poisoning
▪ It can be cultivated by adding 7.5% to 10% NaCl

A

Staphylococcus aureus

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7
Q

Heat stable exotoxins

A

A-E and G-J

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8
Q

These Enterotoxins are associated to food poisoning
(diarrhea, vomiting); reheating contaminated food
will not prevent disease

A

A, B and D

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9
Q

This enterotoxin is linked to pseudomembranous enterocolitis

A

Enterotoxin B (superantigen)

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10
Q
  • Formerly known as Enterotoxin F
    (superantigen-activate aggressive immune
    response)
  • Causes menstruating-associated TSS (Tampon
    use) absorbed through vaginal mucosa
A

Toxic Shock Syndrome Toxin (TSST-1)

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11
Q

▪ Also known as Exfoliatin serotypes A and B
▪ Causes SSS (Scalded Skin Syndrome or Ritter
disease) and bullous impetigo (large pustules with
erythema)

A

Epidermolytic toxins A and B

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12
Q

Destruction of neutrophils and macrophages

A

Panton-Valentine Leukocidin (γ-Hemolysin)

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13
Q

Lyse erythrocytes

A

Hemolysins (α, β, δ)

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14
Q

▪ Conversion of fibrinogen to fibrin
▪ Bound Coagulase & Free Coagulase

A

Coagulase (Staphylocoagulase)

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15
Q

Dissolve fibrin clots and may enable spread
of infection.

A

Fibrinolysin (Staphylokinase)

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16
Q

Cleaves protein

A

Deoxyribonuclease (DNAse)

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17
Q

Hydrolyzes hyaluronic acid in connective
tissues

A

Hyaluronidase

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18
Q

Hydrolyzes lipids in the skin

A

Lipase

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19
Q

Binds to the Fc portion of IgG, neutralizes it and block phagocytosis

A

Protein A

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20
Q

Breakdown of beta-lactam ring in
penicillin molecule

A

Beta lactamase (Penicillinase)

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21
Q

mild inflammation of hair follicle or sebaceous gland

A

Folliculitis

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22
Q

large, raised, superficial abscess

A

Furuncles (boils)

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23
Q

invasive lesions develop from multiple furuncles, may progress into deeper tissues

A

Carbuncles

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24
Q

pustules are larger and surrounded by a small zone of erythema

A

Bullous Impetigo

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25
Q

extensive exfoliative (profuse peeling) dermatitis caused by staphylococcal exfoliative or epidermolytic toxin.

A

Scalded Skin Syndrome (Ritter disease)

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26
Q

fatal disease characterized by sudden onset of fever, chills, vomiting, diarrhea, muscle aches, and rash, w/c could lead to hypotension and shock.

A

Toxic Shock Syndrome

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27
Q

clinical manifestation w/ multiple causes; it is most commonly drug induced, but some cases may have been linked to infections and vaccines.

A

Toxic Epidermal Necrolysis (TEN)

28
Q

Enhances organisms adhesion to implanted medical devices and provides refractoriness to host defense.

A

Exopolysaccharide “slime” or biofilm

29
Q

What is the organism that is associated with Hospital acquired UTI and prosthetic valve endocarditis?

A

Staphylococcus epidermidis

30
Q

This organism adheres to the epithelial cells lining the urogenital tract. It also causes UTI in sexually active, young females and in older women with indwelling catheters

A

Staphylococcus saprophyticus

31
Q
  • Coagulase negative (can give (+) slide method, but tube method negative)
  • Community associated and hospital acquired infections (endocarditis and UTI)
A

Staphylococcus lugdunensis

32
Q

encodes for oxacillin resistance

A

Gene mecA

33
Q
  • Vancomycin resistance
  • Community associated and hospital acquired infections (endocarditis and UTI)
A

Staphylococcus haemolyticus

34
Q

Enriched isolation of Staphylococci

A

Blood Agar

35
Q

Selective medium for Gram-positive cocci

A

Colistin-nalidixic acid or Phenylethyl Alcohol agar

36
Q

Selective and differential for Staphylococcus

A

Mannitol Salt Agar

37
Q

CULTURAL CHARACTERISTICS:

medium to large; round, smooth, entire, translucent, creamy; mostly pigmented yellow and is beta hemolytic

A

S. aureus

38
Q

CULTURAL CHARACTERISTICS:

small to medium; translucent, gray-white colonies, non hemolytic

A

S. epidermidis

39
Q

CULTURAL CHARACTERISTICS:

large; smooth, opaque, convex; usually white, yellow or orange

A

S. saprophyticus

40
Q

This organism is positive in Microdase

A

Micrococcus

41
Q

This organism is resistant to Bacitracin and Furazolidone, but susceptible to Lysostaphin.

A

Staphylococcus

42
Q

This organism is susceptible to bacitracin and furazolidone but resistant to lysostaphin.

A

Micrococcus

43
Q
  • Test for the ability of bacteria to convert fibrinogen into fibrin.
  • Differentiate Staphylococcus aureus from coagulase negative staphylococci
A

Coagulase Test

44
Q

Detects bound coagulase “clumping factor”

A

Coagulase Slide Test

45
Q

Detects free coagulase

A

Coagulase Tube Test

46
Q

Test the ability of the organism to hydrolyze DNA

A

DNase test

47
Q
  • Selective and differential Medium
  • Test for the ability to ferment mannitol.
  • Contains NaCl (7.5%), D-mannitol, phenol red
A

Mannitol Fermentation Test

48
Q

Test for the position of cytochrome to produce a dark-blue end product when reacted with the Reagent

A

Microdase Test (Modified oxidase)

49
Q

Latex Agglutination Test

A

Immunodiagnosis

50
Q

PCR amplification or Nucleic Acid Probes

A

Molecular Testing

51
Q

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry

A

MALDI-TOF MS

52
Q

isolates that are resistant to nafcillin or oxacillin

A

MRSA/MRSE (methicillin-resistant staphylococci)

53
Q

gold standard for MRSA detection (detection of mecA gene)

A

Nucleic acid probes/PCR amplification

54
Q

BORSA

A

borderline oxacillin-resistant S. aureus

55
Q

VISA

A

vancomycin-intermediate S. aureus

56
Q

VRSA

A

vancomycin-resistant S. aureus)

57
Q
  • useful in discrepant macrolide test results
  • Modified double-disk diffusion test
  • detects inducible (detectable in vitro when the bacteria are also exposed to erythromycin) clindamycin resistance
A

Macrolide Resistance

58
Q

These organisms are positive in PYR test.

*S. aureus is negative

A

S. lugdunensis & S. intermedius

59
Q

What organism is susceptible to NOVOBIOCIN and what is the organism that is resistant to it?

A

Susceptible: S. epidermidis
Resistant: S. saprophyticus

60
Q

This organism is positive in Coagulase, DNAse and MSA Fermentation test.

A

S. aureus

61
Q

what is the test that will show the hydrolysis of the surrounding medium if positive?

A

DNase test

62
Q

There would be a development of blue to purple-blue color in this test if positive.

A

Microdase Test (Modified oxidase)

63
Q

this test will differentiate Staphylococcus aureus from coagulase negative staphylococci

A

Coagulase Test

64
Q

Positive: Clot of any size
(S. aureus)

Negative: No clot
(S. epidermidis and others)

A

Coagulase Tube Test

65
Q

Positive:
Macroscopic clumping (white fibrin
clots) (S. aureus, S. lugdunensis, S.
schleiferi)

Negative:
No clumping (smooth milky suspension)
(S. epidermidis and others)

A

Coagulase Slide Test

66
Q

Growth with fermentation: Yellow
halos surrounding growth.
(S. aureus)

Growth without fermentation:
Plate remains pink to red
(S. epidermidis)

A

Mannitol Fermentation Test

67
Q

Susceptible: Zone diameter
greater than 16 mm
(S. epidermidis)

Resistant: Zone diameter less
than or equal to 16 mm
(S. saprophyticus)

A

Novobiocin Susceptability

BACT211 (LECTURE) (18 decks)

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