Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

CLS 753 > Micro - Gram Positive Cocci > Flashcards

Micro - Gram Positive Cocci Flashcards

1
Q

We see gram positive cocci. If the catalase test is positive, the genus is likely… If the catalase test is negative, the two genera are likely…

A

Staphylococcus

Streptococcus or Enterococcus

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

The most virulent species of Staphylococcus is

A

Staph aureus

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

Staph aureus can cause these diseases (4)

A

Food poisoning (toxins)

Toxic shock syndrome

Pyogenic diseases (bullous impetigo, boils, abscesses, folliculitis)

Systemic disease (pneumonia, septicemia)

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

Staph aureus has this in its cell wall that makes it virulent… What does it do?

A

Protein A (antigenic)

Prevents phagocytosis

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

Can Staph aureus be cultured in high salt conditions?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Staph aureus - screening media (2)

A

MSA
-high salt

CHROMagar Staph

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

How does S. aureus compare with S. epidermidis on an MSA plate?

A

S. aureus = ferment mannitol, turns plate yellow

S. epidermidis = does not ferment mannitol, plate stays same color

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do S. aureus colonies look like on a blood agar plate and describe their color? Are they hemolytic and if so, what type of hemolysis?

A

Creamy, buttery
Pale to yellow colonies

Yes, beta-hemolytic
-most are hemolytic, but some are not

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

What do S. aureus look like under the microscope

A

Gram positive cocci, grape-like clusters

-due to multiple planes of division

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

Staph aureus is coagulase…

A

Positive

-slide, tube, or latex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

A common drug resistant stain of Staph aureus is called… How is the resistance gene induced in the lab?

A

MRSA
-certain strains now also vancomycin resistant

Methicillin resistance gene (mecA) induced in a high salt environment

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

MRSA strains are detected with this plate…

A

MSA with oxacillin salt

  • high salt induces methicillin resistance gene
  • oxacillin inhibits normal Staph aureus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Besides culturing, rapid results for MRSA include (2)

A

PCR - mecA gene

Latex agglutination to detect penicillin binding protein 2a

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

Catalase positive, coagulase negative organisms (3). What type of hemolysis?

A

Staph epidermidis
Staph saprophyticus
Staph lugdeninsis

None/gamma

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

S. epidermidis is a normal flora commonly found on ___. S. saprophyticus is a pathogen commonly found in this type of infection…

A

Skin

UTI
-sexual active young females

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

S. epidermidis and S. lugdeninsis can form ___ on artificial heart valves, leading to…

A

Biofilm

Endocarditis

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

Coagulase negative Staph colonies have this color on a blood agar plate… Are they hemolytic?

A

White colonies

No

-appear microscopically similar to S. aureus

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

S. saprophyticus is resistant to this antibiotic. What should the zone size be?

A

Novobiocin

<= 16mm

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

This genus looks like Staph on a gram stain and is catalase positive and coagulase negative. They have this unique morphology on a gram stain

A

Micrococcus

Tetrad

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Streptococcus pyogenes is a part of what Lancefield group? Members of that group are associated with this level of hemolysis

A

Group A

Beta-hemolysis

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

S. pyogenes infection causes acute ___, which can lead to these 2 other conditions

A

Pharyngitis

Rheumatic fever
Glomerolonephritis

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

S. pyogenes causes these 2 skin conditions

A

Impetigo
-usually in children

Necrotizing fasciitis

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

Bullous impetigo and non-bullous impetigo are caused by what organisms (genus/species)?

A

Bullous impetigo = Staph aureus
-flat, crusted with redness

Non-bullous impetigo = Staph aureus or Strep pyogenes
-raised, swollen

24
Q

Is S. pyogenes an aerobic or anaerobic organism? What special culturing condition does it need? How would we mimic this condition on the media?

A

Anaerobe

Increased CO2

Stab the agar

25
A skin specimen contains suspected S. pyogenes. Why must we use culture media that selects for the organism? What culture plate should we use to isolate the organism??
Sample may contain many other organisms and normal flora Blood agar with sulfa (trimethoprim) disc
26
S. pyogenes - what is the definitive confirmation test and the test result?
PYR = positive
27
Name an important Group B Streptococcus species. What type of hemolysis does it have?
Streptococcus agalactiae Weakly beta-hemolytic
28
Does Group B Streptococcus have increased or decreased hemolysis when cultured with Staph aureus. Why?
Increased Releases CAMP, which interacts with beta-lysin from S. aureus to enhance hemolysis -CAMP is definitive test for Group B Strep
29
Group B Strep clinical diseases (3)
Neonatal meningitis Neonatal pneumoniae Post-partum endometritis -mnemonic = Group B is Bad for Babies
30
Group B Strep can be confused with this species due to the types of people it targets and the diseases it causes
Listeria monocytogenes - affects neonates and pregnant women as well - small, narrow zones of beta-hemolysis
31
Group B - pregnant woman's vaginal and rectal swabs should be cultured in this media overnight
LIM broth | -culture on sheep blood agar after growth
32
Strep dysgalactiae is considered to be a part of both Lancefield groups... What type of hemolysis?
C and G Beta-hemolysis
33
Strep dysgalactiae show clinical findings and infections similar to this other Strep species
Strep pyogenes
34
Strep pneumoniae has what type of hemolysis?
Alpha hemolysis | -no Lancefield grouping
35
Strep pneumoniae can show two types of colony morphology
Flat, dull/matte Mucoid, shiny, glistening
36
Strep pneumoniae has these unique microscopic morphologies (2)
Diplococcus Lancet - flat where the 2 cells touch, pointed on adjacent ends
37
Strep pneumoniae clinical findings (4)
Pneumoniae Meningitis Sinusitis Otitis media
38
Strep pneumoniae optochin test result
Sensitive
39
What will happen if Strep pneumoniae is tested in a bile salt solution? What does the test result indicate?
Cells will lyse Strep pneumoniae is bile soluble
40
The group of Streptococcus that are normal flora in the oral cavity are collectively called...
Viridans Streptococci | -biofilm formation = dental caries
41
Streptococcus viridans can cause these clinical findings (3)
Dental caries Bacteremia (after dental work) Subacute endocarditis
42
What 2 tests do we use to differentiate S. pneumoniae from S. viridans? What are the results?
S. pneumoniae = optochin sensitive, bile soluble S. viridans = optochin resistant, bile insoluble -opposite results
43
Streptococcus bovis belongs to this group of Streptococcus. It does not generally cause infections except for...
viridans -also Lancefield group D Endocarditis
44
Can nutritionally variant streptococci (NVS) grow on blood agar? How can we see its growth?
No Co-culture with Staph aureus to see growth as satellite colonies
45
What type of hemolysis do Enterococcus have?
Gamma-hemolysis (none)
46
The two important species of Enterococcus are. They are both resistant to this drug...
E. faecalis E. faecium Vancomycin -VRE = vanco resistant Entero
47
On the gram stain, Enterococcus can be confused with... Enterococci look like...
Streptococcus pneumoniae Pairs or short chains -larger, more plump than Strep
48
Enterococcus clinical findings (3)
Bacteremia Urinary tract infections Subacute endocarditis -hospital acquired infections
49
What 3 tests should we do for non-hemolytic (gamma) cocci? What genus are we trying to rule in or out?
PYR High salt broth (6.5%) Bile esculin -do PYR first; rapid test Enterococcus
50
Enterococcus - catalase test result
Negative, but with weak bubbles
51
Name the 2 important beta-hemolytic Strep species. What two tests should we do to differentiate them and what are the test results?
Strep pyogenes = PYR positive, CAMP negative Strep agalactiae = PYR negative, CAMP positive -opposite results
52
Name the 2 important alpha-hemolytic Strep species. What two tests should we do to differentiate them and what are the test results?
Strep pneumoniae = optochin sensitive, bile soluble Strep viridans = optochin resistant, bile insoluble - opposite results - don't do PYR and CAMP
53
Which Lancefield serotypes are most commonly seen in the lab?
A-H -also K-T, but not common in the lab
54
Streptococcus colony size on an agar plate are usually... Are they bigger or smaller than Staphylococcus?
<= 0.5mm Smaller
55
What two test results should we expect to rule out Enterococcus from Streptococcus?
Enterococcus PYR = positive Bile esculin = positive

CLS 753 (12 decks)

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