Staphylococci Flashcards

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1
Q

Staphylococci is derived from the Greek word staphle, meaning

A

Bunch of grapes

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2
Q

Appearance of staph on BAP

A

Creamy, white or gold, “buttery looking”, some are B hemolytic

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3
Q

How many units of Bacitracin is used in Taxo A disk test?

A

0.02-0.04 units

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4
Q

Bacitracin susceptible

A

Micrococci

> or = 10mm zone of inhibition

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5
Q

Furazolidone susceptible

A

Staphylococci (> or = 15mm zone of inhibition)

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6
Q

How many grams of furazolidone is used in the susceptibility test?

A

100ug

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7
Q

Furazolidone Resistant

A

Micrococcus (6-9mm)

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8
Q

Lysostaphin Sensitive

A

Staphylococci (10-16mm zone of inhibition)

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9
Q

Reagent in Modified Oxidase Test/Microdase Test

A

Tetramethnyl-p-phenylenediamine in dimethylsulfoxide

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10
Q

Positive result in Modified Oxidase Test

A

Blue color within 2 minutes

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11
Q

Organism positive with Modified Oxidase Test

A

Micrococci

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12
Q

Organism that grows on Furoxone-Tween 80-oil red O agar

A

Micrococci

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13
Q

Acid production from glycerol (+)

A

Staphylococci

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14
Q

Aureus means

A

Gold

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15
Q

Resposible for the golden yellow pigment of S. aureus

A

Lipochrome

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16
Q

Salt requirement of Staph

A

7.5 - 10% NaCl

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17
Q

Extensive exfoliative dermatitis that occurs primarily in newborns

A

SSS - Skin Scalded Syndrome

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18
Q

Multisystem disease characterized by a sudden onset of fever, chills, vomiting, diarrhea, muscle aches and rash, which can quickly progress to hypotension and shock

A

Toxic Shock Syndrome (TSS)

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19
Q

Promotes the formation of fibrin layer around staphylococcal abscess

A

Coagulase

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20
Q

Spreading factor enzyme

A

Hyaluronidase/Duran-Reynal Factor

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21
Q

Has fibrinolytic activity

A

Staphylokinase/Fibrinolysin

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22
Q

Fat-splitting enzyme

A

Lipase

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23
Q

Lowers the viscosity of exudates, giving pathogen more mobility

A

DNAse and Phosphatase

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24
Q

Breaks down penicillin and other beta-lacta, drugs

A

Beta-lactamase

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25
Q

Enterotoxins are heat- (stable or labile)???

A

Stable

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26
Q

Enterotoxin often found in milk products

A

Enterotoxin B

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27
Q

Enterotoxin associated with pseudomembranous enterocolitis

A

Enterotoxin B

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28
Q

Enterotoxins responsible for food poisoning

A

Enterotoxins A, B, and D

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29
Q

Pore-forming exotoxin that attacks and kills WBC

A

Leukocidin/Panton-Valentine Leukocidin (Cytolytic Toxin)

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30
Q

Destroys sphingomyelin and RBC around nerves

A

Beta hemolysin (hot-cold lysin/sphingomyelinase C)

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31
Q

Hemolysin that is associated with Leukocidin

A

Delta hemolysin

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32
Q

Serine protease that destroys the stratum granulosum

A

Exfoliatin A and B (superantigens)

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33
Q

Toxin that causes SSS or Ritter’s disease

A

Exfoliatin A and B

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34
Q

Enterotoxin that causes TSS

A

Enterotoxin F/Pyogenic Exotoxin

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35
Q

Immunologically active substance found in the cell wall of S. aureus

A

Protein A

36
Q

Best single criterion of pathogenicity of S. aureus

A

Coagulase Test

37
Q

Reagent in coagulase Test

A

Rabbit plasma or human plasma

38
Q

Detects cell bound coagulase

A

Slide method

39
Q

Detects free coagulase (definitive test)

A

Tube method

40
Q

Positive result in slide method

A

Clot within 30 seconds

41
Q

Positive result in Coagulase Tube Method

A

Clot after 1-4 hrs of incubation

42
Q

MSA content

A

1% Mannitol and 7.5% NaCl

43
Q

pH indicator of MSA

A

Phenol Red

44
Q

Positive result in Mannitol Fermentation Test

A

Yellow color

45
Q

Test to differentiate S. aureus (+) from S. intermedius (-)

A

VP Test

46
Q

+ result in VP test

A

Pink color due to acetoin/acethylmethyl carbinol production

47
Q

Medium and reagent in DNAse test

A

DNA medium and methyl green dye

48
Q

+ result in DNAse test

A

Clearing of the dye (clear zone)

49
Q

Normal flora of the skin

A

S. epidermidis

50
Q

Most common contaminant of prostatic heart valves

A

S. epidermidis

51
Q

CoNS, Novobiocin Susceptible (16-27mm)

A

S. epidermidis

52
Q

CoNS, Novobiocin resistant (6-12mm)

A

S. saprophyticus

53
Q

Associated with catheter-related bacteremia and endocarditis

A

S. lugdunensis

54
Q

Catalase Test Reagent

A

3% H202

55
Q

Aerobic Catalase Test Reagent

A

3% H202

56
Q

Anaerobic Catalase Test Reagent

A

15% H202

57
Q

Catalase Test (+) result

A

Bubble formation/effervescence

58
Q

Organisms that exhibit pseudocatalase reaction

A

Aerococcus
Rothia
Enterococcus

59
Q

Weak production of bubbles should be interpreted as

A

Negative

60
Q

Positive result in PYR test

A

Red color

61
Q

Reagents in VP Test

A

Aplha naphthol and KOH

62
Q

Most useful and widely used Beta-Lactamase Test

A

Cephalosporinase Test

63
Q

Positive result in ceohalosporinase Test

A

Deep pink/red color within 10 minutes

64
Q

Cefoxitin Disk Diffusion Test Result if Sensitive

A

> or = 22mm

65
Q

Cefoxitin Disk Diffusion Test Result if resistant

A

< or = 21 mm

66
Q

Test for the detection of heteroresistant Vancomycin-intermediate S. aureus (VISA)

A

Macro E test

67
Q

Double-Disk Diffusion Test (D Test) positive result

A

Flattening of the one side of the clindamycin zone - “D zone” due to erm gene

68
Q

Used to detect inducible cindamycin resistance in staphylococci

A

D test

69
Q

Procedure for D test (2 steps)

A
  1. Place 15ug erythromycin disk (inducing agent) and 2 ug clindamycin disk 15mm-26mm apart on BAP with the isolate to be tested.
  2. Incubate overnight at 35 C.
70
Q

Confirmatory Tests for Oxacillin Resistance in Staphylococci

A

Broth dilution and E-test

71
Q

Gold standard for MRSA detection

A

PCR

72
Q

Using citrated tubes instead of EDTA in coagulase tests can cause false

A

+

73
Q

In coagulase tube method, >4 hours or delay in interpretation causes false

A

Negative (due to staphylokinase)

74
Q

Negative result in Mannitol fermentation test

A

Red

75
Q

Positive result in HCl precipitation test

A

No precipitation

76
Q

True or False

Catalase is not a pathogenic or virulence factor

A

True

77
Q

S. aureus like that is lactose (+)

A

S. schleiferi

78
Q

S. aureus like

Slide coag (+)
VP (-)
A

S. intermedius

79
Q

S. aureus like

Slide coag (+)
PYR (+)
A

S. lugdunensis

80
Q

S. aureus like

Beta hemolytic
Coag (-)

A

S. haemolyticus

81
Q

Screening test for staphylococci

A

Catalase test

82
Q

1 ocular pathogen

A

S. aureus

83
Q

Causative agent of IV drug user associated endocarditis

A

S. aureus

84
Q

1 cause of Osteomyelitis

A

S. aureus

85
Q

1 cause of skin infections

A

S. aureus

86
Q

BAP: white, non-hemolytic colony

A

S. epidermidis

87
Q

Best sample for staphylococci

A

Aspirated Sample