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Bacteriology > Gram Positive Cocci > Flashcards

Gram Positive Cocci Flashcards

0
Q

Alcohols and other solvents cause the cell wall to _____________.

A

Crenate

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1
Q

Cell wall composition of gram-positive cocci

A

High concentration of peptidoglycan and a low level of lipid in the cell wall

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2
Q

True or False: Alcohols and other solvents do not penetrate the gram positive cell wall

A

True

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3
Q

Natural habitat of GP cocci

A

Skin and mucous membranes in humans; In dust and inanimate objects

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4
Q

Mode of transmission

A

Direct contact

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5
Q

Family Micrococcaceae: Four genera

A

Micrococcus, Staphylococcus, Planococcus, Stomatococcus

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6
Q

Organisms that may colonize human skin but are rarely infectious

A

Micrococcus

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7
Q

Organisms from the marine environment

A

Planococcus

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8
Q

Organisms emerging as rare opportunistic pathogens

A

Stomatococcus

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9
Q

Members of the Micrococcaceae are catalase (positive/negative)

A

Positive

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10
Q

Facultative anaerobes and ferment glucose anaerobically

A

Staphylococcus

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11
Q

Strict anaerobes; utilize glucose oxidatively/non-saccharolytic

A

Micrococci

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12
Q

Resistant to 200 ug/ml of lysostaphin and modified oxidase positive

A

Micrococci

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13
Q

Susceptible to lysostaphin and modified oxidase negative

A

Staphylococci

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14
Q

A peptidase that breaks the glycine peptide linkages in the CW of Staphylococci

A

Lysostaphin

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15
Q

Resistant to 0.04 units of bacitracin

A

Staphylococcus

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16
Q

Susceptible to 0.04 units of bacitracin

A

Micrococcus

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17
Q

Genus Staphylococcus: Catalase (positive/negative)

A

Positive

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18
Q

Genus Staphylococcus: Modified Oxidase (positive/negative)

A

Negative

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19
Q

Grows in 7.5-10% NaCl

A

Staphylococcus

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20
Q

Easily isolated on Blood Agar, Collistin-Nalidixic Acid (CNA), or Mannitol Salt Agar (MSA)

A

Staphylococcus

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21
Q

Typically arranged in pairs or chains and are pinpoint, flat, colorless colonies with wide zones of hemolysis

A

Streptococcus

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22
Q

Describe the colonies of Staphylococci on blood agar

A

Medium convex, creamy, and dome shaped. Pigment varies from white to golden yellow

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23
Q

Selective medium with a blood agar base that contains antibiotics collistin and nalidixic acid

A

Collistin-Nalidixic Acid (CNA)

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24
Q

Medium selective for gram-positive cocci; inhibits gram-negative bacilli

A

CNA

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25
Q

MSA contains ______________________.

A

7.5-10% NaCl, carbohydrate alcohol mannitol and phenol red indicator

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26
Q

Medium typically used to isolate Staphylococcus

A

MSA

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27
Q

Fermentation of alcohol is characterized by a _______________ as phenol red indicator takes up its acidic color.

A

Yellowing of the medium

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28
Q

Hemolytic pattern of most strains of S. aureus

A

Narrow zone of beta hemolysis

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29
Q

Medium to large colonies with a convex, creamy appearance

A

S. aureus

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30
Q

Test to differentiate S. aureus from other Staph species

A

Coagulase test (positive)

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31
Q

Measured in the coagulase slide test

A

Bound coagulase or Clumping factor

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32
Q

The appearance of white fibrin clots in the coagulase slide test (positive result) indicates the conversion of ___________.

A

Fibrinogen to fibrin

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33
Q

If the coagulase slide test is negativem what must be performed next?

A

Coagulase tube test

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34
Q

What does the coagulase tube test detect?

A

Free coagulase

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35
Q

An extracellular toxin which reacts in the presence of coagulase reacting factor (CRF)

A

Free coagulase

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36
Q

A compound normally found in plasma to form coagulase-CRF complex

A

CRF

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37
Q

The coagulase tube test is checked every 30 minutes since some strains of S. aureus produce this which may cause false negative results

A

Staphylokinase/Fibrinolysin

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38
Q

Most virulent species of staphylococci encountered

A

S. aureus

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39
Q

The S. aureus skin infection that involves the epidermis; Typified by the production of vesicles that rupture and
crust over

A

Impetigo

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40
Q

Normal flora of human anterior nares, nasopharynx, perineal area, and skin; can colonize various epithelial or mucosal surfaces

A

Staphylococcus aureus

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41
Q

Normal flora of human skin and mucous membranes; distributed widely, often in large numbers, over body surface

A

Staphylococcus epidermidis

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42
Q

Normal human flora similar to S. epidermidis but present in fewer numbers

A

S. haemolyticus and S. lugdunensis

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43
Q

Normal flora of human skin and mucosa of genitourinary tract

A

Staphylococcus saprophyticus

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44
Q

Normal flora of human skin, mucosa, and oropharynx

A

Micrococcus spp.

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45
Q

Produces and secretes toxins and enzymes that have a role in virulence

A

Staphylococcus aureus

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46
Q

Virulence factors that act on host cell membranes and mediate cell destruction (S. aureus)

A

Alpha, beta, gamma, and delta toxins

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47
Q

Virulence factor that mediates destruction of phagocytes (S. aureus)

A

Leucocidin (Panton Valentine Leucocidin)

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48
Q

Virulence factors that enhance invasion and survival in tissues (S. aureus)

A

Clumping factor, coagulase, and hyaluronidase

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49
Q

Production enhances organism adhesion and provides conditions refractory to antibiotic action and host defense mechanisms (S. epidermidis)

A

Exopolysaccharide “slime” or biofilm

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50
Q

Its propensity to acquire and disseminate antimicrobial resistance allows for survival in hospital setting.

A

Staphylococcus epidermidis

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51
Q

Mode of transmission: Spread of patient’s endogenous strain to normally sterile site by traumatic introduction (e.g., surgical wound or microabrasions)

A

Staphylococcus aureus

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52
Q

Also may be transmitted persounwashed hands of health care workers, especially in the nosocomial setting

A

Staphylococcus aureus

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53
Q

May be transmitted from infected skin lesion of health care worker to patient

A

Staphylococcus aureus

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54
Q

Spread of patient’s endogenous strain to normally sterile site, usually as a result of implantation of medical devices

A

Staphylococcus epidermidis

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55
Q

Person-to-person spread in hospitals can lead to patients becoming colonized and potentially infected with antibiotic-resistant strains

A

Staphylococcus epidermidis

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56
Q

MOT: Introduction of endogenous flora into sterile urinary tract notably in young, sexually active females

A

Staphylococcus saprophyticus

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57
Q

A community-acquired infection, not considered an agent of nosocomial infections

A

Staphylococcus saprophyticus

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58
Q

Infections generally involve intense suppuration and destruction (necrosis) of tissue.

A

Staphylococcus aureus

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59
Q

Ubiquitous member of normal flora makes this species the most commonly encountered in clinical specimens, usually as a contaminant

A

Staphylococcus epidermidis

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60
Q

The exfoliatin toxins cause extensive sloughing of epidermis to produce a burnlike effect on the patient; usually affects neonates

A

Scalded Skin Syndrome (SSS)

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61
Q

Toxin that has several systemic effects, including fever, desquamation, and hypotension potentially leading to shock and death.

A

Toxic shock syndrome toxin (TSST-1)

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62
Q

Most commonly encountered coagulase-negative staphylococci

A

S. epidermidis

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63
Q

Frequently found as contaminants in clinical specimens because they are ubiquitous colonizers

A

Coagulase-negative staphylococci

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64
Q

Medium to large; smooth, entire, slightly raised, translucent; most colonies pigmented creamy yellow; most colonies beta-hemolytic

A

S. aureus

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65
Q

Small to medium; translucent, gray-white colonies; most colonies nonhemolytic; slime-producing strains are
extremely sticky and adhere to the agar surface

A

S. epidermidis

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66
Q

Medium; smooth, butyrous and opaque; beta-hemolytic

A

S. haemolyticus

67
Q

Medium to large; smooth, glossy, entire edge with slightly domed center; unpigmented or cream to yellow-orange

A

S. lugdunensis

68
Q

Large; entire, very glossy, smooth, opaque, butyrous, convex; usually white but colonies can be yellow or orange

A

S. saprophyticus

69
Q

True or False: Micrococcaceae will grow on 5% sheep blood and chocolate agars but not MacConkey agar

A

True

70
Q

Species that may give a positive slide coagulase

test other than S. aureus

A

S. lugdunensis and S. schleiferi

71
Q

Coagulase tube test: Specimen of choice

A

Plasma containing EDTA; not citrate

72
Q

Positive for both the 2-hour PYR and ornithine decarboxylase tests

A

S. lugdunensis

73
Q

Can be found as part of the normal upper respiratory flora; Leading cause of bacterial pneumonia
and meningitis.

A

S. pneumoniae

74
Q

May be carried in the upper respiratory tract of human but it is rarely considered as normal flora

A

S. pyogenes

75
Q

Usually are only capable of causing infections in severely compromised patients

A

Leuconostoc spp. and Pediococcus spp

76
Q

MOT: Person to person by direct contact with mucosa or secretions, or by contaminated droplets produced by coughs or sneezes

A

S. pyogenes

77
Q

Normal flora of female genital tract and lower gastrointestinal tract; may occasionally colonize upper respiratory tract

A

S. agalactiae

78
Q

MOT: Infections in fetuses and infants are acquired by person-to-person transmission from mother in utero or during delivery

A

S. agalactiae

79
Q

MOT: Person-to-person spread by contact with contaminated respiratory secretions

A

S. pneumoniae

80
Q

Normal flora of human oral cavity, gastrointestinal tract, and female genital tract

A

Viridans streptococci

81
Q

MOT: Most notably results from dental manipulations with subsequent transient bacteremia

A

Viridans streptococci

82
Q

Found in soil, food, water, and as normal flora of animals, birds, and humans

A

Enterococcus spp.

83
Q

Species found in plants, vegetables, dairy products

A

Leuconostoc spp.

84
Q

Found in foods and vegetation

A

Lactococcus spp. and Pediococcus spp.

85
Q

Environmental; occasionally found on skin

A

Aerococcus spp.

86
Q

Not only contribute to virulence but are also responsible for the beta-hemolytic pattern of S. pyogenes on blood agar plates

A

Streptolysin O and Streptolysin S

87
Q

Virulence Factor (S. pyogenes): Mediates epithelial cell attachment

A

Protein F

89
Q

Virulence Factor (S. pyogenes): Antiphagocytic

A

M protein

90
Q

S. pyogenes produces enzymes and hemolysins that contribute to tissue invasion and destruction (Give the 5)

A

Streptolysin O/S, streptokinase, DNase, Hyaluronidase

91
Q

Mediate production of rash (i.e., scarlet fever)

A

Streptococcal pyrogenic exotoxins

92
Q

Cross-reactions of antibodies produced against streptococcal antigens and human heart tissue (disease)

A

Rheumatic fever

93
Q

Deposition of antibody-streptococcal antigen complexes in kidney results in damage to glomeruli (disease)

A

Acute, poststreptococcal glomerulonephritis

94
Q

Causes Rheumatic fever

A

S. pyogenes

95
Q

Causes acute, poststreptococcal glomerulonephritis

A

S. pyogenes

96
Q

Causes acute pharyngitis, impetigo, erysipelas, necrotizing fasciitis, myositis, and bacteremia

A

S. pyogenes

97
Q

Causes pneumonia and scarlet fever

A

S. pyogenes

98
Q

Its capsular material interferes with phagocytic activity and complement cascade activation

A

S. agalactiae

99
Q

Infections most commonly involve neonates and infants, often preceded by premature rupture of mother’s membranes

A

S. agalactiae

100
Q

Infections of this organism may be classified as early or late onset

A

S. agalactiae

101
Q

Infections caused by this Strep group occur in patients with underlying malignancies

A

Group G streptococci

102
Q

Occasionally have been associated with acute pharyngitis (Strep group)

A

Group C streptococci

103
Q

Inhibits phagocytosis; Primary virulence factor of S. pneumoniae

A

Polysaccharide capsule

104
Q

Leading cause of meningitis and pneumonia with or without meningitis; sinusitis, otitis media

A

S. pneumoniae

105
Q

Virulence factor of Viridans streptococci that enhances attachment to host cell surfaces

A

Production of extracellular complex polysaccharides

106
Q

Plays a key role in the development of dental caries

A

S. mutans (Viridans streptococci)

107
Q

Generally considered to be of low virulence (Strep)

A

Viridans streptococci

108
Q

Adhesion, cytolysins, and other metabolic capabilities may allow these organisms to proliferate as nosocomial pathogens

A

Enterococus spp.

109
Q

Most common cause of acute pharyngitis, impetigo and erysipelas

A

S. pyogenes

110
Q

“Flesh-eating bacteria”

A

S. pyogenes

111
Q

Causes scarlet fever (exotoxin and organism involved)

A

Streptococcal pyrogenic exotoxins (SPE); S. pyogenes

112
Q

Typified by multisystem involvement that includes renal

and respiratory failure, rash, and diarrhea (dse, org and toxin)

A

Streptococcal TSS caused by SPE (S. pyogenes)

113
Q

Manifested by fever, carditis (inflammation of

heart muscle), subcutaneous nodules, and polyarthritis

A

Rheumatic fever

114
Q

Characterized by edema, hypertension, hematuria, and proteinuria

A

Acute Glomerulonephritis

115
Q

Mediated by antigen-antibody complexes that deposit in glomeruli, where they (S. pyogenes) initiate damage.

A

Acute Glomerulonephritis

116
Q

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

A

S. agalactiae

117
Q

Greening streptococci

A

Viridans

118
Q

Formal name of Abiotrophia spp.

A

Nutritionally variant streptococci

119
Q

Grow on 5% sheep blood and chocolate agars but not MacConkey agar

A

Micrococcaceae

120
Q

Grow in the presence of salt and ferment mannitol produce colonies surrounded by a yellow halo

A

S. aureus

121
Q

Visible growth on 5% sheep blood and chocolate agars incubated at 35C in CO2 or ambient air occurs within _____ of inoculation (Micrococcaceae)

A

24 hours

122
Q

Incubation time required before growth is detected in MSA and other selective media

A

48-72 hours

123
Q

May also ferment mannitol resembling S. aureus in MSA

A

S. saprophyticus

124
Q

Not lysed with lysostaphin

A

Micrococcus spp and other related genera

125
Q

Resistant to furazolidone

A

Micrococcus spp and other related genera

126
Q

Susceptible to bacitracin

A

Micrococcus spp and other related genera

127
Q

Microdase positive

A

Micrococcus spp and other related genera

128
Q

Lysed with lysostaphin

A

Staphylococci

129
Q

Bacitracin resistant

A

Staphylococcu

130
Q

Furazolidone resistant

A

Staphylococci

131
Q

Microdase negative

A

Staphylococci

132
Q

Staphylococci are: (a) anaerobic (b) aerobic (c) facultatively anaerobic

A

(C) Facultatively anaerobic

133
Q

Important agent of dogbite wound infections and may be misidentified as S. aureus if only coagulase testing is performed

A

S. intermedius

134
Q

Positive for both the 2-hour PYR and ornithine decarboxylase tests

A

S. lugdunensis

135
Q

Intrinsically more resistant to the antimicrobial agents commonly used in hospitals and is especially resistant to all currently available cephalosporins and aminoglycosides (genus)

A

Enterococci

136
Q

Capable of acquiring and exchanging genes that encode resistance to antimicrobial agents (genus)

A

Enterococci

137
Q

First clinically relevant group of grampositive cocci to acquire and disseminate resistance to vancomycin

A

Enterococci

138
Q

The single cell–wall active agent available for use against gram-positive organisms resistant to betalactams

A

Vancomycin

139
Q

Typically lancet-shaped and occurs singly, in pairs, or in

short chains

A

S. pneumoniae

140
Q

May elongate to form coccobacilli, although cocci are the primary morphology.

A

Leuconostoc

141
Q

Organisms discussed in this chapter will grow on standard laboratory media such as 5% sheep blood and chocolate agars except ________.

A

Abiotrophia and Granulicatella

142
Q

Abiotrophia and Granulicatella will not grow on MacConkey agar but will grow on _______. (Give 2)

A

CNA (Columbia agar with colistin and nalidixic acid) and PEA (phenylethyl alcohol agar).

143
Q

Supplied on blood and chocolate agars for Abiotrophia and Granulicatella to grow on these media

A

Pyridoxal (Vitamin B6)

144
Q

Media used to detect genital carriage of group B streptococci during pregnancy

A

Todd-Hewitt broth with antimicrobials

145
Q

Use of Todd-Hewitt broth with antimicrobials

A

Suppresses the growth of vaginal flora and allow growth of S. agalactiae following subculture to blood agar

146
Q

Visualization of beta-hemolysis is enhanced by ___________.

A

Anaerobic conditions (Stab inoculating loop)

147
Q

Most organisms (Streptococcus) will grow on agar media within __________ of inoculation.

A

48 hours

148
Q

_________ streptococci may have a distinctive buttery odor.

A

Beta hemolytic

149
Q

Grayish white, transparent to translucent, matte or glossy; large zone of beta hemolysis

A

Group A beta hemolytic streptococci

150
Q

Larger than group A streptococci; translucent to opaque; flat, glossy; narrow zone of beta hemolysis; some strains
nonhemolytic

A

Group B beta hemolytic streptococci

151
Q

Grayish white, glistening; wide zone of beta hemolysis

A

Group C beta hemolytic streptococci

152
Q

Grayish white, small, matte; narrow to wide zone of beta hemolysis

A

Group F beta hemolytic streptococci

153
Q

Grayish white, matte; wide zone of beta hemolysis

A

Group G beta hemolytic streptococci

154
Q

Small, gray, glistening; colonies tend to dip down in the center and resemble a doughnut (umbilicated) as they age; if organism has a polysaccharide capsule, colony may be mucoid; alpha-hemolytic

A

S. pneumoniae

155
Q

Minute to small, gray, domed, smooth or matte; alpha-hemolytic or nonhemolytic

A

Viridans

156
Q

Small, cream or white, smooth, entire; alpha-, beta-, or non-hemolytic

A

Enterococcus spp.

157
Q

Can be used to identify Group A Streptococci

A

PYR test

158
Q

Can be used to identify Group B Streptococci

A

CAMP or Hippurate test

159
Q

Only species of beta-hemolytic streptococci that will give a positive PYR reaction.

A

S. pyogenes

160
Q

Able to hydrolyze hippurate and is positive in the CAMP test.

A

S. agalactiae

161
Q

Detects production of a diffusible, extracellular protein that enhances the hemolysis of sheep erythrocytes by Staphylococcus aureus

A

CAMP test

162
Q

Positive CAMP test

A

Appearance of an arrowhead shape at the juncture of the S. agalactiae and S. aureus streaks

163
Q

Confirmatory and is based on the ability of bile salts to lyse S. pneumoniae

A

Bile Solubility Test

164
Q

Presumptive test for S. pneumoniae

A

Optochin Test

165
Q

Produce a zone of inhibition (optochin)

A

S. pneumoniae

166
Q

Grow up to the disk (optochin-resistant)

A

Viridans

Bacteriology (1 decks)

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