Catalase Positive GPCs Flashcards

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1
Q

Three genera of catalase positive GPCs

A

Staphylococcus, Micrococcus, Rothia

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2
Q

Purpose of CNA (or PEA) and SBA

A

For specimen w/ normal flora

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3
Q

Purpose of Mannitol Salt Agar

A

For outbreaks

- Staphylococcus aureus is mannitol positive

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4
Q

Two types of catalase test

A

Slide catalase and plate catalase

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5
Q

What happens during a catalase test?

A

H2O2 dissociates to H2 + O2

- Positives will bubble

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6
Q

Coagulase test purpose

A

Major test to separate Staphylococci into 2 categories

  • Coagulase positive Staph
  • Coagulase negative Staph (CoNS/CNS)
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7
Q

What is coagulase?

A

Enzyme that creates a thrombin-like substance, clots human or rabbit PLASMA

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8
Q

Oxidation-Fermentation (OF) Test Principle

A

One oiled tube and one not
Fermenter: yellow in oiled and unoiled tube
Oxidizer: yellow in ONLY unoiled tube
Non-oxidizer/asaccharolytic: no acid in either tube

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9
Q

Novobiocin/Furazolidone susceptibility test

A

Determines susceptibility/resistance to antibiotic

- Zone of inhibition is measured after 18-24 hours

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10
Q

Lysostaphin test

A

Lysis Staphylococcus

  • positive = clear (lysis)
  • negative = turbid (no lysis); Micrococcus
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11
Q

Catalase results for

  1. S. aureus
  2. S. epidermidis
  3. S. saprophyticus
  4. Micrococcus
A
  1. positive
  2. positive
  3. positive
  4. positive
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12
Q

Fermenter or oxidizer?

  1. S. aureus
  2. S. epidermidis
  3. S. saprophyticus
  4. Micrococcus
A
  1. Fermenter
  2. Fermenter
  3. Fermenter
  4. Oxidizer
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13
Q

Susceptibility or resistance to Furazolidone

  1. S. aureus
  2. S. epidermidis
  3. S. saprophyticus
  4. Micrococcus
A
  1. susceptible
  2. susceptible
  3. susceptible
  4. resistant
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14
Q

Susceptibility or resistance to novobiocin

  1. S. aureus
  2. S. epidermidis
  3. S. saprophyticus
  4. Micrococcus
A
  1. susceptible
  2. susceptible
  3. resistant
  4. susceptible
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15
Q

Coagulase (slide/tube)

  1. S. aureus
  2. S. epidermidis
  3. S. saprophyticus
  4. Micrococcus
A
  1. positive
  2. negative
  3. negative
  4. negative
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16
Q

Slide coagulase

- Other names?

A

Clumping factor or bound coagulase

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17
Q

Tube coagulase

- Other names?

A

Staphycoagulase or free coagulase

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18
Q

Micrococcus

- Common colonial characteristics

A

Yellow/orange or “sticky”

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19
Q

Staphylococcus aureus

- common colonial characteristics

A

Large, opaque, may be “golden”, usually beta hemolytic

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20
Q

Coagulase negative Staph

- Common colonial characteristics

A

Large, opaque, usually white, usually alpha or gamma hemolytic

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21
Q

Name the main S. aureus infections

A
Skin infection
Wound infection
Food poisoning
Scalded Skin Syndrome
Toxic Shock Syndrome
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22
Q

Name the Coag Neg Staph infections

A

Subacute endocarditis

Catheter/Shunt infections

23
Q

Name the S. saprophyticus infection

A

Primarily urinary tract infections

24
Q

Food poisoning

  • Infections and intoxications
  • Timing of symptoms
  • Stool sample needed?
A

Infections: 2-3 days for symptoms to show and yes stool sample is needed
Intoxications: 2-8 hours for symptoms to show and stool would not be helpful

25
Q

Why would stool not be helpful in food poisoning caused by S. aureus?

A

Toxin is present instead of bacteria

26
Q

List important patient symptoms/conditions that define Toxic Shock Syndrome

A

Fever
Rash
Desquamation
Shock (hypotension)

27
Q

List virulence factors for S. aureus

A
  • Protein A
  • Catalase
  • Coagulase
  • Hyaluronidase
  • DNase
  • Other: capsules, enterotoxins, exotoxins, beta-lactamses
28
Q

Protein A

A

1 cause of S. aureus virulence

  • Binds to Fc portion of IgG
  • Interferes w/ phagocytosis
29
Q

S. aureus food poisoning toxin is what type of toxin?

A

Enterotoxin which is an exotoxin

30
Q

S. aureus’s Scalded Syndrome toxin is what type of toxin?

A

Exotoxin (exofoliatin)

31
Q

S. aureus Toxic Shock Syndrome is produced by what?

A

TSST-1

- Toxic Shock Syndrome Toxin

32
Q

Define MSSA

A

Methicillin Susceptible S. aureus

33
Q

Define MRSA

A

Methicillin Resistant S. aureus

34
Q

Define VISA or GISA

A

Vancomycin Intermediate S. aureus

35
Q

Define VRSA

A

Vancomycin Resistant S. aureus

36
Q

Hospital acquired MRSA vs. Community acquired MRSA

A

HA-MRSA: highly resistant, requires isolation of patients

CA-MRSA: not as highly resistant, usually skin infections in otherwise healthy people

37
Q

Screening patients for MRSA

A
  • Oxacillin (or vancomycin) screening plates

- PCR test for mecA gene (nasal swab)

38
Q

Screening colonies for MRSA

A
  • FDA approved automated methods (VITEK-II)

- Cefoxitin disk test → predicts oxacillin resistance

39
Q

How do they detect staph carriers in hospital setting? How do we protect from it?

A
  • B/c it colonizes on hospital staff → perform nasal screens

- HANDWASHING

40
Q

Staphylococcus lugdunensis

  • How is it confused w/ S. aureus
  • How can they be differentiated?
A
  • May have a positive slide coagulase test, may be beta-hemolytic
  • It will be positive on the slide coagulase test so run the tube coagulase and it will be negative
41
Q

Where is S. saprophyticus most often found?

A

Mostly urinary tract infections in sexually active, young females

42
Q

Rothia mucilaginosa

  • Made of?
  • Infection?
  • What does it look like?
A
  • Normal oral flora
  • Endocarditis and septicemia (esp. drug users and patients w/ malignancies)
  • colonies often “sticky”
43
Q

Urinary Tract Infections

A

S. saprophyticus

44
Q

Dog Bites

A

S. intermedius

45
Q

Septicemia in drug users

A

Rothia mucilaginosa

46
Q

Subacute endocarditis

A

CoNS

47
Q

Acute endocarditis

A

S. aureus

48
Q

Toxic Shock Syndrome

A

S. aureus

49
Q

Scalded skin syndrome

A

S. aureus

50
Q

Food poisoning

A

S. aureus

51
Q

Impetigo

A

S. aureus

52
Q

Cellulitis

A

S. aureus

53
Q

Carbuncles/Furuncle

A

S. aureus

54
Q

Endocarditis

A

Rothia mucilaginosa