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General Microbiology Study > Gram Positive Bacteria > Flashcards

Gram Positive Bacteria Flashcards

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1
Q

Microscopically, the gram-positive cells within the genus Streptococcus are generally arranged in what form?

A

pairs or chains

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2
Q

Streptococcus can be differentiated based on traditional systems of classification. These systems of differentiation include

A

1) hemolysis
2) cell wall structure
3) Lancefield Classification
4) antibody reactions to specific bacterial antigen
5) biochemical identification

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3
Q

T/F Enterococci are commensal organisms of the human gastrointestinal (GI) tract causing variety of opportunistic infections.

A

TRUE

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4
Q

Name the two most common Enterococci causing infection in humans.

A

E. faecalis

E. faecium

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5
Q

Beta-hemolytic streptococci are characterized by ____________ __________, based on carbohydrates within their cell wall.

A

Lancefield groups

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6
Q

Beta-hemolytic streptococci include large colony-forming pyogenic strains representing what Lancefield groups?

A

group A antigen

group B antigen

group C antigen

group G antigen

group L antigen

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7
Q

The viridans group contains small colony-forming beta-hemolytic strains which may type with what Lancefield groups?

A

group A antigen

group C antigen

group F antigen

group G antigen

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8
Q

S. pyogenes, of Lancefield group A, produces two virulence factors contributing to its hemolysis profile. What are they?

A

streptolysin O

streptolysin S

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9
Q

S. pyogenes produces Streptolysin S.

Is Streptolysin S oxygen-stable or oxygen-labile?

A

Streptolysin S is an oxygen-stable.

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10
Q

Streptolysin S and Streptolysin O are capable of lysing what cell types?

A

erythrocytes

leukocytes

platelets

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11
Q

S. pyogenes produces Streptolysin O.

Is Streptolysin O oxygen-stable, or oxygen-labile?

A

Streptolysin O is an oxygen-labile.

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12
Q

S. pyogenes may release what elements producing scarlet fever?

A

streptococcal pyrogenic exotoxins (SPEs)

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13
Q

T/F

S. pyogenes SPE’s act as supertoxins.

A

TRUE

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14
Q

Immune system poststreptococcal diseases are mediated by the presence of what?

A

The M protein (found only in Lancefield Group A)

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15
Q

S. dysgalactiae subsp equisimilis (Lancefield groups A, C, G, and L) clinically produces a similar spectrum of disease as what other S. species?

A

S. pyogenes

(i.e., pharyngitis, skin and soft tissue infections, and bacteremia)

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16
Q

The viridans group of streptococci includes five groups, each containing several species. Name the viridans groups.

A

mitis group

mutans group

anginosus group (previously S. milleri group)

bovis group

salivarius group

MMA is BS

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17
Q

Veridans group S. anginosus group are normal microbiota of what sites?

A

oropharynx

GI tract

urogenital GI tract

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18
Q

Veridans S. anginosus group are normal microbiota of what sites?

A

oropharynx

GI tract

urogenital tract

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19
Q

A wide variety of enterococci species can be isolated from human infections.

What two species of enterococci are more pathologically involved?

A

E. faecalis

E. faecium

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20
Q

PYR stands for what?

A

pyrrolidonyl arylamidase

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21
Q

Streptococci and enterococci are observed primarily in pairs or chains due to what factor?

A

Cellular division for streptococci and enterococci occurs along a single axis.

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22
Q

The ixodes tick is a vector for what three diseases?

A

Borrelia burgdorferi

Ananplasma

Babesia

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23
Q

The differentiation of enterococci, group D streptococci, and lactococci from other Streptococci has been traditionally based on what?

A

The organisms ability to hydrolyze esculin in the presence of 40% bile.

Enterococci, group D streptococci, and lactococci can all hydrolyze esculin in the presence of bile.

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24
Q

What is a bile esculin test used for?

A

The bile esculin test is used to differentiate Enterococci and Group D Streptococci from other Gram+, CoN streptococci.

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25
Q

T/F

Bile esculin agar is both selective and differential.

A

TRUE

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26
Q

What makes bile esculin agar selective?

A

sodium azide and oxagall; which inhibit the growth of G- and most G+.

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27
Q

What makes bile esculin agar differential?

A

Esculin.

Very few organisms can hydrolyze in the presence of bile.

Enterococci and Group D Streptococci both hydrolyze esculin in the presence of bile.

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28
Q

Enterococci and Group D Streptococci both hydrolyze __________ in the presence of _________.

A

esculin (in the presence of ) bile

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29
Q

S. agalactiae types to what Lancefield Group(s)?

A

Lancefield Group B

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30
Q

S. dysgalactiae subsp. equisimilis may type to what Lancefield Group(s)?

A

Lancefield Groups A, C, G, & L

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31
Q

S. pyogenes may type to what Lancefield Group(s)?

A

Lancefield Group A

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32
Q

S. anginosus group may type to what Lancefield Group(s)?

A

Lancefield Group A, C, G, & F

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33
Q

The beta-hemolytic streptococci may have a distinctive odor resembling what?

A

butter

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34
Q

Viridans streptococci have what type of odor?

A

Butterscotch odor, especially on chocolate agar.

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35
Q

Grouping of organisms based on cell wall carbohydrate structure is known as what?

A

Lancefield classification

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36
Q

S. pyogenes is the only species of beta-hemolytic streptococci associated with human infections that will produce what?

A

A positive PYR reaction.

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37
Q

A brown halo around colonies on bile esculin agar and a positive PYR reaction is generally indicative of what genus?

A

Enterococcus

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38
Q

Colonies suspected as S. pneumoniae would be further verified by what additional tests?

A

optochin sensitivity (+)

bile solubility (+)

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39
Q

A positive PYR identifies what Lancefield Group?

A

Lancefield Group A (S. pyogenes)

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40
Q

A positive hippurate or CAMP test identifies what Lancefield Group?

A

Lancefield Group B (S. agalactiae)

41
Q

What does CAMP stand for?

A

Christie, Atkins, Munch-Petersen

42
Q

Describe gross morphology of S. pneumoniae on visual inspection.

A

small

gray

moist

center of colony may be depressed

alpha-hemolytic

43
Q

Name a singular key species that is optochin sensitive. (Producing zone of inhibition.)

A

S. pneumoniae

44
Q

Name an organism that is optochin resistant. (Growth up to the disk.)

A

S. viridans group

(with the exception of S. pneumoniae).

45
Q

Name four GPC’s that are optochin sensitive, producing zones of inhibition.

A

S. pneumoniae

S. pseudopneumoniae

S. mitis

S. oralis

46
Q

An organism reveals as a G+ alpha-hemolytic isolate.

Name a key species and two aditional groups or genus to be considered.

A

S. pneumoniae

viridans group

enterococci

47
Q

For antimicrobial susceptibility testing, what does MIC stand for?

A

minimum inhibitory concentration

48
Q

All gram-positive bacteria demonstrate intrinsic antibiotic resistance to what three agents?

A

colistin

nalidixic acid

aztreonam

49
Q

In association with S. pyogenes, streptococcal pyrogenic exotoxins (SPEs) may be released resulting in scarlet fever.

Scarlet fever occurs in association with, or subsequent to, what ailment?

A

streptococcal pharyngitis

50
Q

Beta-hemolytic streptococci are also referred to as __________ __________.

A

pyogenic streptococci

MCM, p 411

51
Q

Name three key species of beta-hemolytic streptococci.

A

S. pyogenes

S. agalactiae

S.dysgalactiae subsp. equisimilis

52
Q

Name three key species of the small-colony-forming S. anginosus group.

A

S. anginosus

S. constellatus

S. intermedius

53
Q

Transmission of streptococcal infections can occur by different routes. Pathogenic species like S. pyogenes and S. pneumoniae are primarily transmitted through __________ or __________.

A

droplets

direct contact

54
Q

All pathogenic streptococci are __________ __________ upon exposure to 3% hydrogen peroxide

A

catalase negative

55
Q

A false-positive catalase reaction may occur if bacteria are grown on or contaminated with what?

A

blood agar / blood media

56
Q

The cell wall composition of typical Gram-positive bacteria consists mainly of

A

peptidoglycan, with glucosamine and muramic acid as amino sugars and galactosamine as a variable component.

57
Q

T/F

Streptococci are facultative anaerobes.

A

TRUE

58
Q

The optimum temperature for growth of most streptococcal species lies between

A

35°C and 37°C

59
Q

Group B streptococcal (GBS) attack rates are highest in what patient populations?

A

< 1 yoa and > 65 yoa

60
Q

Asymptomatic pharyngeal colonization with S. pyogenes occurs in what % of the adult population?

A

less than 5% of the adult population

61
Q

S. agalactiae colonization rates of the urogenital and gastrointestinal tracts in women and men is demonstrated in what percent of the adult population?

A

10% - 30%

62
Q

Nonsuppurative S. pyogenes complications include __________ & __________.

A

acute rheumatic fever

glomerulonephritis

63
Q

poststreptococcal glomerulonephritis is linked with skin infections from what organism?

A

S. pyogenes

64
Q

STSS may be associated with S. pyogenes. What does STSS stand for?

A

streptococcal toxic shock syndrome

65
Q

The clinical spectrum of disease caused by S. dysgalactiae subsp. equisimilis resembles infections caused by what other bacterial species?

A

S. pyogenes

66
Q

The clinical spectrum of disease caused by S. pyogenes resembles infections caused by

A

S. dysgalactiae subsp. equisimilis

67
Q

S. pneumoniae belongs to what two more broad groups?

A

S. mitis group

S. viridans group

68
Q

Members of the S. mitis group are regular commensals of what regions of the body.

A

oral cavity

gastrointestinal tract

female genital tract

69
Q

Streptococcus anginosus Group are all small-colony-forming bacteria (colony size, ≤0.5 mm) that can display variable patterns of

A

hemolysis (alpha, beta, or gamma)

70
Q

S. bovis group blood infections particularly S. _______ are associated with gastrointestinal disorders, including colon cancer and chronic liver disease

A

S. gallolyticus subsp. gallolyticus

71
Q

S. bovis group blood infections particularly S. gallolyticus subsp. gallolyticus are associated with gastrointestinal disorders, including __________ & __________.

A

colon cancer

chronic liver disease

72
Q

Name three species of GPC from the Streptococcus anginosus group.

A

S. anginosus

S. constellatus

S. intermedius

73
Q

S. pyogenes is the most common cause of acute

A

pharyngitis

74
Q

This antigen is common to all S. pneumoniae serotypes

A

C-polysaccharide antigen

75
Q

T/F

Several nucleic acid-based methods for the detection of S. agalactiae colonization in pregnant women have been developed.

A

TRUE

76
Q

With respect to potential rapid methods for the detection, what does “NAAT” stands for?

A

nucleic acid amplification tests

77
Q

Name the beta-hemolytic streptococci of the pyogenic group.

A

S. pyogenes

S. agalactiae

S. dysgalactiae subsp. equisimilis

78
Q

Colony size of the beta-hemolytic streptococci pyogenic group are about what size after 24 hours of incubation?

A

>0.5 mm after 24 hours

79
Q

Within the viridans group, nonhemolytic gray colonies are typical for what two species?

A

S. bovis

S. salivarius

80
Q

Detection of the Lancefield group F antigen in small-colony- forming streptococci allows a fairly reliable identification of a strain as a member of what group.

A

S. anginosus group

81
Q

The presence of the enzyme __________ __________ is often tested to distinguish S. pyogenes from other beta- hemolytic streptococci.

A

pyrrolidonyl aminopeptidase

82
Q

Pyrrolidonyl aminopeptidase is produced by what species of beta-hemolytic streptococci?

A

S. pyogenes

83
Q

It is important to distinguish Streptococcus from Enterococcus prior to performing what test?

A

PRY testing.

Other genera including Abiotrophia, Aerococcus, Enterococcus, Gemella, and Lactococcus may also be PYR positive.

84
Q

Does S. pyogenes generally reveal to be bacitracin susceptible or resistant?

A

bacitracin susceptible

85
Q

The CAMP factor reaction was first described in 1944 by Christie, Atkins, and Munch-Petersen and refers to the __________ __________ of erythrocytes by the beta-hemolysin of staphylococcus aureus and the extracellular CAMP factor of streptococcus agalactiae.

A

synergistic lysis

86
Q

Peptidoglycan is a crystal lattice structure composed of two primary amino polysaccharides. Name them.

A

N-acetylglucosamine / NAG

N-acetylmuramic acid / NAM

87
Q

DD-transpeptidases bind the sublayers of peptidoglycan (NAG & NAM) and are better known as what?

A

penicillin binding proteins (or PBPs)

88
Q

Beta lactam antibiotics are similar in structure to transpeptidas. As such beta lactams bind penicillin binding proteins rending them unable to bind to the corresponding layer of peptidoglycan. In this way beta lactams interfere with what?

A

Bacterial cell wall synthesis.

89
Q

How do beta lactam antibiotics interfere with cell wall synthesis?

A

Beta lactam binds to penicillin binding protein;

rendering the PBP (DD-transpeptidase) unable to bind to the a corresponding NAG/NAM.

90
Q

Streptoccocus _________ is the species of viridans streptococci most commonly associated with dental caries.

A

mutans

91
Q

Streptococcus sanguinis, of the viridans group streptococci, make __________ , which bind to fibrin platelet aggregates on damaged heart valves.

A

dextrans

92
Q

The M protein represented within the cell wall of some streptococci are found within what Lancefield group?

A

Group A (only)

93
Q

A positive bile esculin test is generally indicative of what?

A

Species belonging to

S. bovis group

or

enterococci

94
Q

Arginine hydrolysis is a key reaction for the identification of what?

A

viridans group streptococci.

95
Q

A positive esculin agar slants reveals as what?

A

A blackening of the media indicates esculin hydrolysis.

No color change indicates a negative esculin hydrolysis test result.

96
Q
A
97
Q

Name this typical nonhemolytic “comet tail or Medusa head or groundglass” colonies observed on 5% sheep-blood agar.

A

B. Anthracis

Gram +ve, bacillus, endospore forming

98
Q

B. anthracis, along with the other species within the genus, are capable of forming spores within the mother cell called what?

A

endospores

99
Q

Streptococci and enterococci are catalase (+ tive or - tive )

A

Catalase negative

  • tive

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