Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

LQB462 > Staphylococci and streptococci > Flashcards

Staphylococci and streptococci Flashcards

(92 cards)

Start Studying
1
Q

Staphylococcus spp. have what Gram reaction?

A

Positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most common arrangement of Staphylococcus spp.?

A

Grape-like clusters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a facultative anaerobe?

A

An organism that can grow in the presence or absence of oxygen; facultative anaerobes are capable of aerobic respiration or fermentation if oxygen is not present.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Are Staphylococcus spp. aerobes, anaerobes, or facultative?

A

Facultative anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List three regions where S. aureus is NRF.

A
  • Skin
  • Nasopharynx
  • Mucosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List two regions where S. epidermidis is NRF.

A
  • Skin

- Mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

List three regions where S. saprophyticus is NRF.

A
  • Skin
  • Genitourinary tract
  • Mucosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Staphylococcus aureus, epidermidis, and saprophyticus are examples of ____ pathogens.

A

Opportunistic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do Staphylococcus aureus, epidermidis, and saprophyticus cause infection?

A

Breaks in the skin/mucosal surface and/or change in the immune system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

List four conditions associated with Staphyloccus aureus, epidermidis, or saprophyticus infection.

A
  • Bacteraemia
  • Toxic shock
  • Wound infections
  • UTI
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Staphylococci are organisms from which phylum?

A

Firmicutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Staphylococci are organisms from which phylogenetic class?

A

Bacilli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Staphylococci are organisms from which phylogenetic order?

A

Bacillales

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Staphylococci are organisms from which phylogenetic family?

A

Staphylococcaceae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Staphylococci are organisms from which phylogenetic genus?

A

Staphylococcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is empirical treatment?

A

Treatment based on pt presentation and knowledge of infections common to that site.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does MCS stand for?

A

Microscopy, culture and sensitivity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the first step of specimen processing?

A

Microscopy - performing a Gram stain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

List three things you would expect to see in microscopy of a wound exudate specimen.

A
  • NRF
  • Potential pathogen
  • PMNs (neutrophils)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What non-selective media is always used to 16-streak a possible bacterial aetiological agent?

A

HBA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What selective media is used to 16-streak a possible bacterial aetiological agent from a skin swab?

A

MSA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What makes HBA a differential media?

A

Haemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is gamma haemolysis (gammaH)?

A

No haemolysis, only nutrient use.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is alpha haemolysis (alphaH)?

A

Incomplete haemolysis, showing a greenish tint.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why does alphaH have a greenish tint?
Green bacteria produce H2O2, reducing haemoglobin to green oxidised methemoglobin.
26
Production of H2O2 which reduces haemoglobin to green oxidised methemoglobin produces what kind of haemolysis reaction on HBA?
AlphaH
27
What is beta haemolysis (betaH)?
Complete haemolysis, showing a clear zone.
28
What makes MSA a selective media?
The high salt concentration (7.5% NaCl, 10X more than most media) which supports Staphylococci and inhibits most other bacteria.
29
What makes MSA a differential media?
The mannitol which differentiates between organisms that can and cannot ferment it.
30
What colour are mannitol fermenting (MF) organisms grown on MSA?
Yellow
31
What colour are non-mannitol fermenting (NMF) organisms grown on MSA?
Pink
32
What organisms grow well on MSA?
Staphylococcus and halotolerant species.
33
How does S. aureus appear on MSA?
Yellow colonies, yellow zone.
34
How does S. epidermidis appear on MSA?
Clear pink colonies, pink agar.
35
How does S. saprophyticus appear on MSA?
Usually pink colonies and agar but 10% of strains ferment mannitol (yellow).
36
S. aureus is ____ haemolytic.
BetaH
37
Is S. aureus MF or NMF?
MF
38
S. epidermidis is ____ haemolytic or ____ haemolytic depending on the strain.
betaH, gammaH.
39
Is S. epidermidis MF or NMF?
NMF
40
Is S. aureus catalase POS or NEG?
POS
41
Is S. epidermidis catalase POS or NEG?
POS
42
Is S. aureus motile or non-motile?
Non-motile
43
Is S. epidermidis motile or non-motile?
Non-motile
44
S. saprophyticus is ____ haemolytic.
GammaH
45
Is S. saprophyticus MF or NMF?
Generally NMF but 10% of strains are MF.
46
S. saprophyticus usually causes what kind of infections?
UTIs
47
Is S. saprophyticus catalase POS or NEG?
POS
48
Is S. saprophyticus motile or non-motile?
Non-motile
49
You have performed a Gram stain and noted GPC in grape-like clusters. What PID should you now perform?
Catalase test
50
A catalase test should only be performed on Gram ____ organisms.
POS
51
A catalase test is usually performed to differentiate between which two genera?
Staphylococcus and Streptococcus
52
What is catalase?
An enzyme produced by microbes living in oxygenated environments to neutralise toxic forms of oxygen metabolites (e.g. H2O2).
53
Why is catalase production a virulence factor?
The host response to various organisms is to produce H2O2 (hydrogen peroxide); neutralising this response helps the organism survive.
54
Blood agar gives what rapid catalase test result?
False POS
55
What catalase test should be performed if only blood agar is available?
Modified rapid catalase (M.R. catalase).
56
A GPC in grape-like clusters that is catalase POS is most likely what genus?
Staphylococcus spp.
57
A GPC in grape-like clusters that is catalase NEG is most likely what genus?
Streptococcus spp.
58
A GPC in grape-like clusters that is pseudo-catalase POS (actually NEG) is most likely what genus?
Enterococcus spp.
59
A catalase test that shows a delayed reaction (≥ 10 sec) with minor effervescence is what kind of reaction?
Pseudo-POS, recorded as NEG.
60
What genus of organisms produces a delayed reaction (≥ 10 sec) with minor effervescence to a catalase test?
Enterococcus spp.
61
What catalase reaction do Enterococcus spp. return?
Pseudo-catalase POS (delayed reaction [≥ 10 sec] with minor effervescence), actually catalase NEG.
62
What is coagulase?
An enzyme that coagulates (clots) blood plasma.
63
How does coagulase clot blood plasma?
Coagulase catalyses conversion of soluble fibrinogen to insoluble fibrin, resulting in a clot.
64
How does producing coagulase protect bacteria?
Coagulase causes clotting around the wound, preventing the immune system entering the region to clear the infection.
65
The tube coagulase test is performed on organisms that test catalase ____.
POS
66
The tube coagulase test is performed on organisms that test ____ POS.
Catalase
67
Is the tube coagualse test a PID or CID?
CID
68
What does the tube coagulase test differentiate between?
S. aureus and other Staphylococcus spp.
69
Is S. aureus coagulase POS or NEG?
POS
70
Is S. epidermidis coagulase POS or NEG?
NEG (CoNS)
71
Is S. saprophyticus coagulase POS or NEG?
NEG (CoNS)
72
What is meant by 'CoNS'?
Coagulase NEG Staphylococcus spp.
73
What is detected by a slide coagulase test?
Bound coagulase/clumping factor
74
A NEG slide coagulase test should be confirmed with what test?
Tube coagulase test
75
Is Staphylococcus latex agglutination a PID or CID test?
CID
76
What test should be performed if a GPC returns a catalase POS then a coagulase NEG result?
Novobiocin susceptibility
77
What two organisms would you suspect if a GPC returned a catalase POS then a coagulase NEG result?
S. epidermidis or S. saprophyticus
78
From what type of agar are colonies taken for a Novobiocin susceptibility test?
Blood agar
79
Is a Novobiocin test a PID or CID?
CID
80
What two Staphylococcus organisms are SENS to Novobiocin?
S. aureus and S. epidermidis
81
Which Staphylococcus organism is RES to Novobiocin?
S. saprophyticus
82
What organism would you ID if a GPC returned a catalase POS, coagulase NEG, then Novobiocin SENS?
S. epidermidis
83
What organism would you ID if a GPC returned a catalase POS, coagulase NEG, then Novobiocin RES?
S. saprophyticus
84
How wide does the zone of clearance have to be for an organism to be RES to Novobiocin?
≤12mm diameter
85
Is an organism with ≤12 mm diameter zone of clearance in a Novobiocin test SUSC or RES?
RES
86
Is an organism with >12 mm diameter zone of clearance in a Novobiocin test SUSC or RES?
SUSC
87
An organism that is coagulase NEG and has a >12 mm diameter zone of clearance in a Novobiocin test is likely to be what genus and species?
Staphylococcus epidermidis
88
An organism with a ≤12 mm diameter zone of clearance in a Novobiocin test is likely to be what genus and species?
Staphylococcus saprophyticus
89
What is used as a substitute for methicillin when testing S. aureus for SUSC or RES?
Cefoxitin
90
A GPC that returned a catalase POS, coagulase POS, and cefoxitin SUSC result would be reported as ____.
MSSA
91
A GPC that returned a catalase POS, coagulase POS, and cefoxitin RES result would be reported as ____.
MRSA
92
An organism RES to cefoxitin is assumed to be RES to ____.
Methicillin

LQB462 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions