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Liz's Microbiology Module 1 > Streptococcaceae and Other Related Genera > Flashcards

Streptococcaceae and Other Related Genera Flashcards

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1
Q

When comparing staph and strep colonies, what are the differences?

A
  • Staph is opaque

- Strep is “transparent” (or at least not as opaque)

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2
Q

Alpha (or gamma) hemolytic Streps

A
  • Group D
  • S. pneumoniae
  • Enterococcus sp.
  • Alpha Strep (not Group D)
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3
Q

Beta hemolytic Streps

A
  • Group A
  • Group B
  • Group D (rarely beta hemolytic)
  • Enterococcus spp. (rarely beta hemolytic)
  • Beta Strep (not Group A, B, or D)
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4
Q

S. pneumoniae characteristic features on a plate

A
  • Colonies are often depressed in center (autolysis) or mucoid (encapsulated)
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5
Q

Throat cultures (strep screens) must be incubated ____?

A

Anaerobically

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6
Q

Streptolysin O is ____ ____

A

Oxygen labile

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7
Q

Streptolysin S is ____ ____

A

Oxygen stable

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8
Q

Principle of the Lancefield grouping test

A

Grouped by “C substance” in cell wall

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9
Q

Streptococci

- Catalase (pos/neg)

A

Catalase negative

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10
Q

Bile Esculin hydrolysis

- Principle

A

To determin an organism’s ability to hydrolyze esculin to esculetin in presence of bile. Esculetin reacts w/ Fe citrate in medium to form black ppt

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11
Q

Bile Esculin agar

- What do pos/neg tests look like?

A

Pos: blackening of medium
Neg: no blackening

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12
Q

LAP

- Principle

A

To determine organism’s ability to produce the enzyme leucine aminopeptidase, which will hydrolyze leucine-a-naphthylamide disk

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13
Q

LAP

- What do pos/neg tests look like?

A

Pos: red
Weak pos: pink
Neg: yellow

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14
Q
  1. 5% NaCl

- Principle

A

To determine an organism’s ability to grow in a high salt environment (6.5%)

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15
Q
  1. 5% NaCl

- What do pos/neg tests look like?

A

Pos: turbid
Neg: clear, no change

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16
Q

PYR

- Principle

A

To determine an organism’s ability to produce the enzyme pyrrolidonyl peptidase

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17
Q

PYR

- What do pos/neg tests look like?

A

Pos: red
Neg: no color change

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18
Q

Optochin susceptibility test

- Principle

A

To determine an organism’s susceptibility to the chemical optochin (ethylhydrocupreine hydrochloride)

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19
Q

Optochin susceptibility test

- What do pos/neg tests look like?

A

Pos: zone of inhibition >= 14 mm
Neg: no zone of inhibition

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20
Q

Bile solubility

- Principle

A

To determine the ability of organisms to lyse in presence of bile salt (sodium desoxycholate)
- Plate and tube method

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21
Q

Bile solubility

- What do pos/neg tests look like?

A

Plate
- Pos: disintegration of colony under desoxycholate drop (flat hemolyzed area remains)
- Neg: no visible change under desoxycholate drop
Tube
- Pos: clearing of “test” but “control” remains turbid (cloudy)
- Neg: both tubes (“test” and “control”) remain turbid (cloudy)

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22
Q

Quellung test

- Principle

A

To determine the ability of the organism’s capusle Ags to bind to known Abs forming a precipitate. Visualized w/ the addition of methylene blue to the slide

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23
Q

Quellung test

- What do pos/neg tests look like?

A

Pos: capsule looks opaque and appears to enlarge around dark blue-stained cell
Neg: no appearance of a clear, enlarged halo surrounding stained cell

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24
Q

Bacitracin

- Principle

A

To detect an oganism’s susceptibility to the anitmicrobial agent bacitracin. Filter paper disks impregnated w/ bacitracin are sued to determine susceptibility or resistance

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25
Q

Bacitracin

- What do pos/neg tests look like?

A

Pos: zone of inhibition
Neg: no zone of inhibiton

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26
Q

CAMP test

- Principle

A

To detect presence of CAMP factor produced by certain organisms that will enhance the beta-hemolytic activity of S. aureus on SBA

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27
Q

Sodium Hippurate

- Principle

A

Hippuric acid is hydrolyzed to benzoic acid and glycine by hippuricase. Glycine end product is detected by addition of ninhydrin reagent

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28
Q

Sodium Hippurate

- What do pos/neg tests look like?

A

Pos: dark blue to purple color
Neg: no color change

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29
Q

Other grouping tools for determining Streptococcus and Enterococcus

A
  • Ag testing (in/direct)
  • Fluorescent Ab (esp. Group A)
  • Kit systems (API, Vitek, etc.)
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30
Q

Latex agglutination

- Principle

A

To dtect certain Ags or Abs in a variety of bodily fluids (blood, saliva, urine, CSF). Sample to be tested is sent to the lab where it’s mixed w/ latex beads coated w/ a specific Ag or Ab.

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31
Q

Coagglutination

- Principle

A

Method used for organism identification using specific, known commercial Abs taht have been attached to a dead bacterium, most often Staphylococcus. Dead Staphylococcus act similarly to a latex bead, allowing Ag-Ab reaction to be visible to the naked eye

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32
Q

Coagglutination

- What do pos/neg tests look like?

A

Pos: visible agglutination w/in 1-2 minutes
Neg: remain smooth

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33
Q

2 types of Ag testing for Streptococcus and Enterococcus sp.

A

Latex agglutination and coagglutination

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34
Q

Who is/are PYR positive?

A
  • Group A

- Enterococcus spp.

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35
Q

Who is/are NaHippurate positive?

A
  • Group B
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36
Q

Who is bacitracin susceptible?

A

Group A

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37
Q

What Strep are LAP positive?

A

All of them we work with in the lab

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38
Q

What test did we use coagglutination on in the lab?

A

Group B

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39
Q

Who is/are quellung test positive?

A

S. pneumoniae

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40
Q

Name all of the ALPHA and gamma hemolytic Strep

A
  • S. pneumoniae
  • Enterococcus sp.
  • Alpha Streptococci (Group D)
  • Alpha Streptococci (not Group D)
41
Q

Who is/are CAMP positive?

A

Group B

42
Q

Tests to run on when you have catalase negative GPCs that are alpha/gamma hemolytic

A
  • Esculin
  • NaCl
  • PYR
  • Bile solubility
  • Optochin
43
Q

Name all of the BETA hemolytic Strep

A
  • Enterococcus sp (rare)
  • Beta Streptococci (Group D) (rare)
  • Beta Streptococci (Group A)
  • Beta Streptococci (Group B)
  • Beta Streptococci (not Group A, B, D)
44
Q

Who is/are bile solubility positive?

A

S. pneumoniae

45
Q

Tests to run when you have catalase negative GPCs that are beta hemolytic?

A
  • PYR
  • Esculin
  • Bacitracin
  • CAMP
  • NaHippurate
  • Coagglutination (not specific for group B but that’s what we used it for)
46
Q

Who can be a pseudocatalase (weak catalase positive)?

A

Enterococcus sp.

47
Q

Who is/are positive for bile esculin?

A
  • Enterococcus sp

- Alpha Streptococci (Group D)

48
Q

Who is/are optochin susceptible?

A

S. pneumoniae

49
Q

Who is/are NaCl positive?

A
  • Group B

- Enterococcus sp

50
Q

Group A/S. pyogenes

  • Hemolysis
  • 2 positive/susceptible tests
A
  • Beta
  • Bacitracin susceptible
  • PYR positive
51
Q

Group B/S. agalactiae

  • Hemolysis
  • 3 positive tests
A
  • Beta
  • CAMP pos
  • NaCl pos
  • NaHippurate pos
52
Q

Not Group A, B, or D are otherwise known as…?

A

Group C, G

53
Q

Group D/S. bovis

  • Hemolysis
  • 1 positive test
A
  • Usually alpha or gamma (rarely beta)

- Esculin pos

54
Q

S. pneumoniae

  • Hemolysis
  • 3 positive tests
A
  • Alpha
  • Optochin susceptible
  • Bile solubility pos
  • Quellung pos
55
Q

Enterococcus sp

  • Hemolysis
  • 3 positive tests
A
  • Alpha (rarely beta)
  • Esculin pos
  • NaCl pos
  • PYR pos
56
Q

Virulence factors of Group A

A
  • M protein
  • Pyrogenic/erythrogenic toxin
  • Streptokinase/fibrinolysin
  • Hyaluronidase
57
Q

M protein

A

Major virulence factor in Group A Strep; resistant to phagocytosis

58
Q

Pyrogenic/erythrogenic toxin

A

Causes the rash of scarlet fever

59
Q

Streptokinase/fibrinolysin

A

Fibrinolysin is the breakdown of fibrin; allows infection to spread (cellulitis, erysipelas)

60
Q

Hyaluronidase

A

Break down of ground substance; allows infections to spread

61
Q

Pyogenic streptococci

A

“pus forming”

  • Group A
  • Group B
  • Groups C, G
62
Q

Common infections caused by Group A Strep

A

Throat and wound

  • “Strep throat”, tonsillitis
  • Scarlet fever
  • Impetigo
  • Erysipelas
  • Cellulitis
  • Necrotizing fasciitis
63
Q

What type of toxin is a pyrogenic toxin?

A

Exotoxin

64
Q

Group A Strep

  • Lacefield group
  • ____ colonies w/ ____ zone of beta hemolysis
A
  • Lancefield group A

- Large colonies; large zone

65
Q

Streptococcal Toxic Shock Syndrome

- Cause by which group of strep?

A

Group A

66
Q

Group A Post streptococcal diseases

A
  • Acute glomerulonephritis

- Rheumatic fever

67
Q

Acute Glomerulonephritis

  • Caused by…
  • Time of infection?
A
  • Ag-Ab complexes causes inflammation of glomeruli (NOT an infection of the kidneys)
  • Occurs 1-2 weeks following pharyngitis or skin infection w/ Group A
68
Q

Acute Rheumatic Fever

  • Cause
  • Location of disease
  • Patient population
  • Time of infection?
A
  • Cross-reaction b/w strep Ag and cardiac tissue
  • Results in damage to heart valves
  • Most frequent in 5-15 year olds
  • Occurs 2-4 weeks after pharyngitis
69
Q

Oxygen requirements for Streptococcus Genera

A

Aerobic or facultative anaerobic

70
Q

Throat cultures are usually ordered for what group of strep?

A

Group A; other beta strep aren’t often treated

71
Q

SXT plate

A

Inhibits normal flora allowing Group A to grow

72
Q

SBA is incubated ____ for Group A “strep screens”

A

Anaerobically

73
Q

Throat “rapid strep screens”

  • Direct Ag detection of Group A strep
  • ____ specificity, ____ sensitivity
A
  • Ag-Ab interaction b/w Ag in specimen and Ab in test kit
  • High; Low → conclusive for pos tests; if patient is symptomatic and direct Ag test is negative, culture should be performed
74
Q

Group A strep treatment

A

GROUP A STREP IS UNIVERSALLY SUSCEPTIBLE TO PENICILLIN

75
Q

Group B strep

  • Lancefield group
  • ____ colonies, ____ hemolytic zone compared to Group A
A
  • Lancefield Group B

- Large; smaller

76
Q

Group B strep may be part of normal ____ flora

A

Urogenital

77
Q

Infections caused by Group B

A
  • Meningitis/septicemia in newborns
  • Female genital and UTIs
  • Post-partum infections
78
Q

CDC guidelines for Group B strep culture during pregnancy

A
  • Should be done for all pregnant women at 35-37 weeks gestation
  • Culture/screen should include vaginal and rectal collection
  • LIM broth (has antibiotics) suppresses GN normal flora
  • If screen/culture is positive, moms need to be treated w/ penicillin
79
Q

Group B Strep

- Post partum infections

A
  • Early onset disease of Group B

- Late onset disease of Group B

80
Q

Early onset disease of Group B

A
  • Baby is < 7 days old
  • Results from vertical transmission (during delivery)
  • High mortality
81
Q

Late onset disease of Group B

A
  • Baby is 1 week to 3 months old

- More than often from parents, caretakers, nosocomial infections

82
Q

Group B

- Gram stain

A
  • GP

- Tiny, round diplococci

83
Q

Groups C, G strep

A

S. dysgalactiae

84
Q

Groups C, G

  • Infections
  • Differentiation
A

May cause pharyngitis (not usually treated)

  • Lower incidence of post streptococcal diseases
  • Not differentiated unless found in blood or CSF (reported as beta streptococci not Group A, B, or D)
85
Q

S. pneumoniae

- Clinical infections

A
  • Community acquired bacterial cause of pneumonia
  • Meningitis, otitis media (ear infection)
  • Carriers asymptomatic (esp in young children)
86
Q

S. pneumoniae

- Treatment and prevention

A
  • Becoming more resistant to antimicrobials

- Vaccinations available for young and older

87
Q

S. pneumoniae

  • Gram stain
  • Colonial morphology
  • Growth requirement
A
  • GP diplococci (football, lancet shaped) or chains
  • Mucoid (encapsulated) or dipped (autolysis) → virulence, typing
  • Capnophilic
88
Q

Viridans Streptococci

- 5 major groups (each w/ multiple species)

A
  • S. salivarius group
  • S. anginosus group
  • S. mitis group
  • S. mutans group
  • S. bovis group
89
Q

Viridans strep

- Causes…

A
  • Subacute endocarditis

- Oral infections (gingivitis and cavities)

90
Q

Which of the 5 major Viridans strep groups has the D Ag?

A

S. bovis

91
Q

Viridans strep

  • Hemolysis
  • LAP pos/neg
  • Bile esculin pos/neg
  • NaCl pos/neg
  • Optochin pos/neg
A
  • Alpha/gamma hemolytic (less commonly beta hemolytic)
  • Not usually further identified unless from blood or CSF cultures
  • All are LAP +
  • Bile esculin neg (except for S. bovis)
  • NaCl neg
  • Optochin neg
  • Reported as either: alpha Streptococci (Gp D) or (not Gp D)
92
Q

Group D Strep

  • Normal flora
  • Causes…
A
  • Gastrointestinal flora

- Septicemia (positive blood cultures)

93
Q

Viridans Strep

- Normal flora

A

Oral, GI, skin

94
Q

Enterococcus sp

  • Normal flora
  • Infections
  • Most common species
A
  • Gastrointestinal
  • Mainly UTI, septicemia, abdominal wounds
  • E. faecalis (more common), E. faecium (more resistant)
95
Q

Enterococcus sp

  • Gram stain
  • Drug resistance to…
A
  • GPC, often elongated

- Multiple drug resistance (VRE → vancomycin drug resistance)

96
Q

Abiotrophia

  • Found in ____ and ____
  • Culture ____ endocarditis
  • Media
A
  • Bacteremia; endocarditis
  • Negative
  • Chocolate agar or S. aureus satellitism
97
Q

Aerococcus sp

  • Gram stain
  • Culture morphology
  • Lap pos/neg
A
  • GPC tetrads or clusters (like Staph)
  • Alpha/gamma hemolysis (like Strep)
  • Lap neg
98
Q

Vancomycin Resistant “Lactic Acid Bacteria”

  • 2 species
  • produces which CHO?
  • Similar in appearance to ____
A
  • Leuconostoc species, Pediococcus species
  • Produces only lactic acid from glucose fermentation (as do Strep)
  • Similar in appearance to “viridans Streptococci”

Liz's Microbiology Module 1 (11 decks)

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