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Bacteriology Lecture (Midterm- Finals) > MIDTERM: Streptococcus & Enterococcus > Flashcards

MIDTERM: Streptococcus & Enterococcus Flashcards

1
Q

Upper respiratory tract and skin lesions

A

S. pyogenes

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2
Q

Upper respiratory microbiota

A

S. pneumoniae

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3
Q

Streptococcus is differentiated from micrococcaeceae through?

A

Catalase Test

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4
Q

The most clinically important Lancefield group A

A

Group A S. pyogenes

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5
Q

One of the most aggressive pathogens encountered in clinical microbiology laboratories

A

Group A S. pyogenes

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6
Q

An oxygen-stable, nonimmunogenic hemolysin capable of lysing erythrocytes, leukocytes, and platelets in the
presence of room air. (20-22C)

A

Streptolysin S

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7
Q

Permits the bacterial adherence to the respiratory epithelium

A

Lipotechoic acid

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8
Q

Immunogenic, capable of lysing the same cells and cultured cells, is broken down by oxygen, and will produce hemolysis only in the absence of room air.

A

Streptolysin O

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9
Q

This is inhibited by the cholesterol in skin lipids, resulting in the absence of the development of protective antibodies associated with skin infection

A

Streptolysin O

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10
Q

Prone to progression with involvement of deeper tissues and organs, a characteristic that has earned the designation in general publications as the “flesh-eating bacteria.”

A

S. pyogenes

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11
Q

These are erythrogenic toxins produced by lysogenic strains. They are heat labile and rarely found in group C and
G streptococci.

A

Streptococcal Pyrogenic Exotoxins (SPEs)

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12
Q

When these organisms gain access to normally sterile sites they can cause life-threatening infections.

A

S. pyogenes and S. pneumoniae

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13
Q

Lancefield group:
Group B

A

S. agalactiae

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14
Q

Lancefield group:
Group C

A

S. dysgalactiae

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14
Q

Lancefield group:
Group D

A

Enterococcus spp. & Streptococcus bovis complex

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15
Q

These are responsible for the beta hemolytic pattern on blood agar plates which is used as a guide to identify this species

A

Streptolysin O and S

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16
Q

This is may be released and produce scarlet fever, which occurs in association with streptococcal pharyngitis and is manifested by a rash of the face and upper trunk.

A

Streptococcal Pyrogenic Exotoxins (SPEs)

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17
Q

Act as superantigens activating macrophages and T-helper cells and inducing the release of powerful immune
mediators

A

Streptococcal Pyrogenic Exotoxins (SPEs)

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18
Q

What are the powerful immune
mediators induced by SPEs

A
  • interleukin (IL)-1, IL-2, IL-6
  • tumor necrosis factor (TNF)-alpha
  • TNF-beta
  • interferons
  • Cytokine
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19
Q

Similar to Staphylococcus toxic shock syndrome except that it’s not from tampons but rather it’s from streptococcal infection, usually through the mouth

A

Streptococcal toxic shock syndrome

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20
Q

This is typified by multi system involvement including renal and respiratory failure, rash, and diarrhea, is a serious disease mediated by production of potent SPE

A

Streptococcal toxic shock syndrome

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21
Q

The most important virulence factor of Streptococcus pyogenes

A

anti-phagocytic cell wall- M protein antibodies

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22
Q

_______ protein is associated with rheumatic fever, and ________ is typically associated with glomerulonephritis

A

Class 1M and class I or II, respectively

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23
Q

Manifested by fever, endocarditis (inflammation of heart muscle), subcutaneous nodules, and polyarthritis

A

Rheumatic fever

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24
Q

Characterized by edema, hypertension, hematuria, and proteinuria

A

Acute Glomerulonephritis

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25
Q

This usually follows respiratory tract infections and is believed to be mediated by antibodies produced against S. pyogenes M protein that cross-react with human heart tissue.

A

Rheumatic fever

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26
Q

Follow respiratory or cutaneous infections and is mediated by antigen-antibody complexes that deposit in glomeruli, where they initiate damage.

A

Acute Glomerulonephritis

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27
Q

Promotes fibrinolytic activity by converting plasminogen to plasmin

A

Streptokinase

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28
Q

This elaborates about 20 extracellular products, including enzymes (streptolysins, hyaluronidase, streptokinase, deoxyribonucleases {DNases}, and nicotamide adenine dinucleotidase {NADase} and pyrogenic (erythrogenic toxins)

A

S. pyogenes

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29
Q

Enhance the spread of the organism through connective
tissues which breakdowns the connective tissue in order to penetrate the deeper tissues

A

Hyaluronidase

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30
Q

Their pathogenic significance is unknown

A

DNase and NADase

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31
Q

These are produced by isolates of Streptococcus pyogenes that was infected with a specific temperate bacteriophage

A

pyrogenic and erythrogenic toxins (has serotypes A, B, and C)

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32
Q

In order to produce pyrogenic toxin they must be infected first by?

A

temperate bacteriophage (similar to cranial
bacterium)

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32
Q

Infections usually are associated with neonates and are acquired before or during the birthing process

A

Group B S. agalactiae

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33
Q

Group B S. agalactiae is known to cause what diseases in newborns?

A
  • septicemia
  • pneumonia
  • meningitis
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34
Q

As per CDC, all pregnant women at ________ of
gestation should have vaginal or rectal specimens collected
and processed for detection of GBS

A

36 to 37 weeks

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35
Q

In this patient population, GBS infection manifests itself as skin and softmtissue infections, intraabdominal abscess, bacteremia, or pneumonia

A

elderly person with a serious underlying disease or immunodeficiency

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36
Q

What are the two pneumococcal vaccines currently available?

A
  • 13-valent Conjugated pneumococcal vaccine (PCV13)
  • 23-valent pneumococcal polysaccharide vaccine (PPSV23)
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36
Q

Streptococcus pneumoniae is seen in the normal flora of the upper respiratory tract about:

A
  • 25% to 50% of preschool children
  • 36% of primary school age children and
  • nearly 20% of adults (carriers of streptococcus pneumonia)
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37
Q

Pneumococcal vaccine used for infants (2 months of age) and children

A

13-valent
Conjugated vaccine or PCV13

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37
Q

Pneumococcal vaccine used for adults especially 65 years older

A

23-valent pneumococcal polysaccharide vaccine or PPSV23

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38
Q

Pneumococcal vaccine used for immunosuppressed
individuals

A

Both PCV13 and PPSV23

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39
Q

A viridans streptococci, bacteremia has been associated with malignancies of the gastrointestinal tract

A

S. bovis

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40
Q

The main virulence factor of Streptococcus pneumoniae

A

Streptococcus anti-phagocytic polysaccharide capsule

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41
Q

It evades phagocytosis and is capable of mobilizing inflammatory cells mediated by its cell wall structure, including peptidoglycan, teichoic acids, and a pneumolysin

A

S. pneumoniae

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42
Q

Activates the classic complement pathway. The
pneumolysin mediates suppression of the oxidative
burst in phagocytes, providing for effective
evasion of immune clearance.

A

Pneumolysin

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42
Q

A viridans streptococci isolated from the oral cavity and blood

A

S. salivarius

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43
Q

A viridans streptococci. Etiologic agent of dental carries

A

S. mutans

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43
Q

Found within the cell wall, which binds receptors
for platelet-activating factor in endothelial cells,
leukocytes, platelets, and tissue cells of the lungs
and meninges providing for entry and spread of
the organism.

A

Phosphorylcholine

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43
Q

Formerly milleri group. Most common viridans streptococci responsible for liver, spleen, and brain abscesses.

A

S. anginosus

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44
Q

One of the subtypes of S. bovis and is isolated from blood cultures of patients with colonic cancer

A

Streptococcus
gallolyticus subsp. gallolyticus

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44
Q

A viridans streptococci that is commonly associated with endocarditis

A

S. mitis

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45
Q

These are not highly invasive; however, they enter tissue during dental or surgical procedures, which could lead to tooth abscesses, abdominal infections, bacteremia, or valve endocarditis and late-onset prosthetic
valve endocarditis

A

Viridan streptococci

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45
Q

Organisms in the _________ typically demonstrate no hemolysis or alpha-hemolysis (greening) on sheep blood agar and smell like butterscotch, especially from _______.

A

streptococcus viridan group and S. anginosus, respectively

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46
Q

This includes a large and complex group of human streptococci that are not groupable by Lancefield serology

A

viridans group

47
Q

Presents as small colony-forming beta-hemolytic strains
with groups A, C, F, and G antigens.

A

S. anginosus group

47
Q

The viridian streptococci that can produce beta hemolysis

A

S. anginosus group

48
Q

Common cause of urinary tract infection in
hospitalized persons

A

Enterococcus

49
Q

This genus is the first clinically relevant group of gram-positive cocci to acquire and disseminate resistance to vancomycin, thus the name vancomycin-resistant Enterococcus (VRE)

A

Enterococcus

50
Q

They are not known to secrete toxins; however, they’re resistant to multiple antibiotics. Causing them to survive and proliferate, especially in patients receiving multiple antimicrobials, causing superinfection.

A

Enterococcus

51
Q

Enterococcus are especially resistant to all currently available?

A

cephalosporins and aminoglycosides

52
Q

Unidentified Enterococci

A
  • Vagococcus fluvialis
  • Lactococcus garvieae
  • Lactococcus lactis
53
Q

These are susceptible to vancomycin and fail to form gas in Mann, Rogoša, and Sharpe (MRS) broth

A

lactococci and vagococci

54
Q

Are sometimes misidentified as enterococci, often called unidentified enterococci.

A
  • Vagococcus fluvialis
  • Lactococcus garvieae
  • Lactococcus lactis
55
Q

To differentiate the two Vagococcus is ______ but Lactococcus is ______

A

motile and nonmotile, respectively

56
Q

These commercial kits have been reported to be very specific, but false negative results may occur if specimens contain low numbers of S. pyogenes

A

Antigen Detection

57
Q

In two throat swabs, If the first swab yields a positive result by a direct antigen method, the second swab can be?

A

discarded

58
Q

In two throat swabs, if those specimens in which the rapid antigen test yielded a negative result, what is the next step?

A

You inoculate the second swab on a blood agar plate or selective streptococcal blood agar plate

59
Q

This is used to increase recovery for diagnosing streptococcal pharyngitis

A

two-plate culture method

60
Q

What culture medias are recommended to be used for two-plate culture method

A

sheep blood agar and trimethoprim-sulfamethoxazole (SXT) blood agar

61
Q

Serologic tests to detect a Streptolysin O and DNase B antibodies in acute and convalescent serum samples are used primarily to diagnose?

A

Acute rheumatic fever and Acute glomerulonephritis following infection with GAS

62
Q

In terms of cultivation, Streptococci grow well in?

A

blood or chocolate agar

63
Q

This agar is preferred because it is a differential media that can present the hemolytic properties of the organism unlike chocolate agar

A

Blood agar plate

64
Q

These will not grow on blood or chocolate agars unless pyridoxal (vitamin B6 ) is supplied either by placement of a pyridoxal disk, by cross streaking with Staphylococcus, or by inoculation of vitamin B6 – supplemented culture media.

A

Abiotrophia and Granulicatella

65
Q

These are nutrient variable pyridoxal- dependent streptococcus

A
  • Streptococcus mitior
  • Abiotrophia or
  • Granulicatella bacteremia
66
Q

For isolating group A streptococci from throat swabs, what is the most common medium used? and what is it supplemented with to suppress the growth of normal microbiota?

A

5% sheep blood agar supplemented with trimethoprimsulfamethoxazole
(SXT)

67
Q

To detect genital carriage of group B streptococci during pregnancy, a vaginal or rectal swab is inoculated into?

A

ToddHewitt broth, such as LIM

68
Q

Contain antimicrobials (gentamicin, nalidixic acid, or colistin and nalidixic acid), which suppresses the growth of normal vaginal microbiota and allows growth of group B S. agalactiae (GBS).

A

Todd-Hewitt broths

68
Q

When LIM broth is subculture to this medium Strep B would produce a mauve color

A

CHROMagar

68
Q

Urine can also be used for Group B Strep infection but it must have _______in a pregnant female to be use as a marker for the possibility of GBS by vaginal carriage

A

> 10^4 CFU/ml

69
Q

A selective differential medium based on the esculin hydrolysis and is also selective by incorporation of inhibitory oxgall (bile salts) to inhibit the growth of other gram-positive organisms

A

Enterococcosel agar

70
Q

These are used for a primary screening to detect vancomycin-resistant enterococci

A

Bile esculin agar and enterococcosel agar with vancomycin

71
Q

Used to detect GBS directly in vaginal rectal specimen or can be used to detect GBS in LIM or Carrot broth culture

A

Nucleic Acid Amplification test

72
Q

In this chromogenic broth media, colonies of beta hemolytic Group B Strep will convert the color of the tube from clear to yellow or orange

A

Carrot broth media

72
Q

These Lancefield group would not change the tube color of Carrot broth media and when used a negative broth, they would still need to be planted into a solid media for the recovery of their strains.

A

nonhemolytic GBS

73
Q

A selective nonchromogenic enrichment broth
can be subcultured unto the ________ in which colonies
of GBS appear yellow to orange for detection.

A

Granada agar

74
Q

Laboratories typically incubate blood or chocolate agar plates in

A

5% to 10% carbon dioxide

74
Q

A disk (Taxo A) is impregnated with a small amount of bacitracin (0.04 units) is placed on an agar plate.

A

Bacitracin Test

75
Q

What are the positive and negative result for Bacitracin Test

A

Positive: Any zone of inhibition greater than10mm; susceptible

Negative: No zone of inhibition; resistant

75
Q

What is the enzyme that hydrolyzes the l-pyrrolidonyl-b-naphthylamide substrate to produce a b-naphthylamine?

A

l-pyrrolidonyl arylamidase

76
Q

Positive and negative results in L-Pyrrolidonyl arylamidase (PYR) test

A

Positive: Bright red (PINK) color within 5 minutes

Negative: No color change or an orange color

76
Q

The reagent in L-Pyrrolidonyl arylamidase (PYR) test

A

N,N-methylamino-cinnamaldehyde

77
Q

Beta hemolysis is enhanced by anaerobic conditions and because of ______________

A

Streptolysin O

78
Q

This agar should be inoculated by stabbing the inoculating loop into the agar several times so that you would be able to observe sub surface hemolysis.

A

Blood agar plates (BAP)

79
Q

Identify the test: Certain organisms (including group B streptococci)produce a diffusible extracellular hemolytic protein (CAMP factor) that acts synergistically with the beta-lysin of Staphylococcus aureus to cause enhanced lysis of red blood cells

A

Christie, Atkins, and Munch-Peterson(CAMP) test

80
Q

In CAMP test, the ____________ are streaked perpendicular to a streak of __________on sheep blood agar

A

group B streptococci and S. aureus , respectively

81
Q

Positive and negative results in CAMP test

A

Positive: Enhanced hemolysis is indicated by an arrowhead shaped zone of beta-hemolysis at the
juncture of the two organisms

Negative: No enhancement of hemolysis

81
Q

These also produces a positive CAMP reaction.

A

Listeria monocytogenes

82
Q

Positive and negative results in Hippurate Hydrolysis Test

A

Positive: deep blue/violet color in 30 minutes

Negative: Colorless or slightly yellow pink color

82
Q

This is a glycine conjugate of benzoic acid and when hydrolysed by an organism
glycine and benzoic acid are formed

A

Hippurate

83
Q

Limitations of Hippurate Hydrolysis Test

A

A false-positive result may occur if incubation with ninhydrin exceeds 30 minutes

83
Q

Positive and negative results in Optochin test

A

Positive: Zone of inhibition at least 14 mm in diameter, with 6-mm disk

Negative: No zone of inhibition

84
Q

Used to differentiate group B streptococci (Streptococcus agalactiae– positive) from other
streptococcal species

A

Christie, Atkins, and Munch-Peterson(CAMP) test

85
Q

Other term for Optochin

A

ethylhydroxycupreine hydrochloride or P disk

85
Q

An antibiotic that interferes with the ATPase and production of adenosine triphosphate(ATP) in microorganisms

A

Optochin

86
Q

This lower the surface tension between the bacterial cell membrane and the medium, thus accelerating the organism’s natural autolytic process.

A

Bile salts

86
Q

This rapidly lyses pneumococcal colonies. Lysis depends on the presence of an intracellular autolytic enzyme, amidase.

A

Bile or bile salt solution (sodium deoxycholate)

87
Q

Positive and negative results in Bile solubility test

A

Positive: Suspension clears

Negative: Suspension remains turbid

88
Q

Considered the gold standard technique for serotyping Streptococcus pneumoniae

A

Quellung test or Newfeld Reaction

88
Q

A microscopic precipitin test that is used to identify pneumococci or to determine the capsular serotype of individual pneumococcal isolates

A

Quellung test or Newfeld Reaction

89
Q

Counterstain used in Quellung test that stain the pneumococcal cells dark blue

A

Methylene Blue

90
Q

If the organism is susceptible to optochin it is presumed that this organism is?

A

Streptococcus pneumoniae

90
Q

This test differentiates Streptococcus pneumoniae (positive; soluble) from alpha-hemolytic streptococci (negative; insoluble

A

Bile solubility test

91
Q

This test is used to detect the capsule of pneumococcus

A

Quellung reaction

92
Q

Positive Quellung reaction

A

Single cells, pair, chains, and clumps of cells

93
Q

This test is used to determine the ability of an organism to grow in high concentrations of salt. It is used to differentiate enterococci (positive) from nonenterococci (negative).

A

Salt tolerance test

94
Q

What is the test medium used in Salt tolerance test?

A

heart infusion broth containing 6.5% NaCl

95
Q

Indicator for acid production in Salt tolerance test

A

small amount of glucose and bromocresol purple

96
Q

This test is used for the presumptive identification of enterococci and organisms in the Streptococcus bovis group. The test differentiates enterococci and group D streptococci from non–group D viridans streptococci

A

Bile Esculin Test

97
Q

Positive and negative results in Bile Esculin Test

A

Positive: Growth and blackening of the agar slant

Negative: Growth and no blackening of medium

98
Q

Identify:
- Susceptible to bacithracin
- Beta-hemolytic
- PYR positive

A

Group A (S. pyogenes)

98
Q

Identify:
- Susceptibility to optochin
- Positive for bile solubility
- Alpha hemolytic
- Colonies are mucoid of flattened with a depressed center
- Quellung test

A

S.pneumoniae

98
Q

Identify:
- Alpha hemolytic streptococci that are optochin resistant and PYRase negative
- Gamma hemolytic streptococci that are PYRase negative and do not grow in 6.5% NaCl

A

Viridans

99
Q

Identify:
- PYRase positive
- Grow in the presence of 6.5% NaCl
- Bile esculin hydrolysis positive

A

Enterococcus

100
Q

Identify:
- Beta-hemolytic
- Hippurate hydrolysis positive
- Positive CAMP test

A

Group B (S. agalactiae)

101
Q

These resemble viridans streptococci on culture but are microscopically similar to staphylococci in that they occur as tetrads or clusters.

A

Aerococci

101
Q

These organisms sometimes show a weak catalase or pseudo catalase reaction. They grow in the presence of 6.5% NaCl and can easily be confused with enterococci

A

Aerococci

102
Q

Their susceptibility pattern can also resemble that of the enterococci. Some strains of these organisms are bile esculin positive and PYR positive.

A

Aerococci

102
Q

Enumerate the streptococcus groups that are susceptible to penicillin

A

Groups A, B, C, and G streptococcus

103
Q

In cases of penicillin allergy, what other tests must be performed?

A

macrolides, clindamycin, and the tetracyclines

103
Q

Test performed if erythromycin resistant

A

a D zone test

104
Q

Clindamycin and erythromycin disks be separated by _________ instead of the 15 to 16mm recommended for testing S. aureus

A

12 mm

105
Q

These are Plasmid-borne

A

van genes

106
Q

Confers high level resistance and predominance to E. faecium and less frequently to E.faecalis

A

vanA, vanB

107
Q

Intrinsic and lower-level in resistance in yellow, motile Enterococcus

A

vanC

Bacteriology Lecture (Midterm- Finals) (9 decks)

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