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[6] LABORATORY DIAGNOSIS OF STAPHYLOCOCCUS AND MICROCOCCUS > Type of Media > Flashcards

Type of Media Flashcards

1
Q

differentiate Staphylococcus from Streptococcus

A

CATALASE TEST

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2
Q

differentiate Micrococcus from Streptococcus

A

OXIDASE TEST; BACITRACIN ST

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3
Q

differentiate S. aureus from CONS

A

COAGULASE TEST

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4
Q

identification test for S. aureus

A

DNAse TEST

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5
Q

differentiate the CONS

A

NOVOBIOCIN ST

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6
Q

Check the presence the bacteria in patient sample

A

PRIMARY OR DIRECT GRAMSTAIN

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7
Q

Lookout for inflammatory or pus cells

A

PRIMARY OR DIRECT GRAMSTAIN

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8
Q

Used as basis for the

secondary gram staining

A

PRIMARY OR DIRECT GRAMSTAIN

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9
Q

Presence of complete hemolysis ( β-hemolytic) on BAM

A

may suggest S. aureus or β-hemolytic streptococci

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10
Q

degrades the red cells in the agar; hence, the clearing on BAM

A

HEMOLYSIN

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11
Q

Absence of hemolysis on BAM

A

γ-hemolytic

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12
Q

makes MSA selective for HALOPHILES

A

High salt concentration (7.5%NaCl)

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13
Q

differentiates MF and MNF on MSA

A

Mannitol fermentation

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14
Q

Fermentation on MSA

A

produces acids = change in pH =

change in color

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15
Q

pH indicator of MSA

A

phenol red = turns red in alkaline pH

and turns yellow in acidic pH

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16
Q

MFs of MSA

A

S. aureus and S. saprophyticus

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17
Q

MNFs of MSA

A

S. epidermidis and S. lugdunensis

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18
Q

allows growth of gram positive cocci, while inhibiting most gram negative microbes on PEA

A

Selective agar

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19
Q

inhibits or markedly reduces the growth of Gram-negative organisms by interfering with DNA synthesis

A

phenylethyl alcohol

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20
Q

used for the selective growth of Staphylococcus and Streptococcus in mixed cultures

A

PHENYLETHYL ALCOHOL AGAR (PEA)

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21
Q

used to isolate most gram-positive and gram-negative anaerobes from enteric samples

A

PEA with sheep’s blood (ENRICHED-SELECTIVE)

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22
Q

inhibits facultative gram-negative rods

A

PEA with sheep’s blood (ENRICHED-SELECTIVE)

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23
Q

COLUMBIA (CNA) AGAR: type of media

A

Enriched/differential/selective medium

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24
Q

supports growth of fastidious organisms on CNA

A

Addition of 5% defibrinated sheep’s blood =

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25
Q

Hemolytic patterns

A

COLUMBIA (CNA) AGAR

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26
Q

binds to LPSs and phospholipidsin the outer cell membrane of Gram-negative bacteria

A

Colistin (10mg)

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27
Q

blocks DNA replication in susceptible bacteria (Gram neg) by inhibiting a subunit of DNA gyrase

A

Nalidixic acid (10mg)

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28
Q

Vogel-Johnson (VJ) Agar: type of media

A

Selective medium; Differential medium

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29
Q

toxic to gram negative bacteria

A

potassium tellurite

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30
Q

favors growth of Staphylococcus spp

A

Lithium chloride and Glycine

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31
Q

Blackish colonies

A

tellurite (colorless) reduction to metallic tellurium (black) = S. aureus

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32
Q

No blackening/ transparent colonies

A

other Staphylococcus

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33
Q

Color change from red to yellow

A

mannitol fermenter

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34
Q

Ph indicator

A

phenol red

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35
Q

color remains red

A

color remains red

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36
Q

Chapman Stone Agar: type of media

A

Selective medium (5.5% NaCl); Differential

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37
Q

Chapman Stone Agar: fermentation

A

mannitol fermentation

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38
Q

turns yellow in acidic pH on CSA

A

bromcresol purple

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39
Q

substrate in Gelatin hydrolysis

A

Gelatin

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40
Q

allows visualization of gelatin liquefaction in Gelatin hydrolysis

A

Ammonium sulfate

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41
Q

Yellow colonies surrounded by clear halo (gelatinase +), MF

A

S. aureus

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42
Q

White nonpigmented colonies with or without clear halo

A

S. epidermidis

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43
Q

Small yellow colonies, MF

A

Enterococcus, Group D strep

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44
Q

Baird-Parker Agar: type of media

A

Enriched medium
Selective medium
Differential medium

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45
Q

enhances growth of Staphylococcus on BPA

A

Sodium pyruvate and glycine

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46
Q

toxic to most microbes esp gram negative bacteria on BPA

A

Tellurite

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47
Q

used for observance of proteolysis (lecithinase-clearing around the colony) and lipolysis (lipase-opaque zone around the colony upon 24H incubation) on BPA

A

Egg yolk

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48
Q

Black, shiny, convex colonies 1-5 mm in diameter with a narrow, white edge, lecithinase and lipase +

A

S. aureus

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49
Q

Black, shiny, irregular shape, Lecithinase –, lipase +

A

S. epidermidis

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50
Q

“staphyle”

A

“staphyle”

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51
Q

Grapelike clustering of gram + cocci

A

STAPHYLOCOCCUS

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52
Q

are commonly seen from broth of STAPHYLOCOCCUS

A

Singles, pairs, tetrads and chains

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53
Q

Resembles Staphylococcus

A

MICROCOCCUS

54
Q

MICROCOCCUS Also produces [?] but shorter

A

clusters

55
Q

MICROCOCCUS are Usually in packets of

A

four or eight

56
Q

Test used to detect the presence of enzyme catalase

A

CATALASE TEST

57
Q

CATALASE TEST: reagent

A

Uses 3% H2O2

58
Q

an enzyme that degrades H2O2 into water and oxygen

A

CATALASE

59
Q

CATALASE Allows the bacteria to survive

A

peroxides

60
Q

CATALASE + result & control

A

effervescence or vigorous bubbling = MICROCOCCACEAE

61
Q

CATALASE - result & control

A

no effervescence or weak to few bubbles = STREPTOCOCCACEAE

62
Q

Determines the presence of cytochrome oxidase

A

OXIDASE TEST; MODIFIED OXIDASE TEST (MICRODASE)

63
Q

used in aerobic respiration -> transfer electron (H) to Oxygen to form water

A

Cytochromes

64
Q

OXIDASE TEST: reagent

A

p-phenylenediamine dihydrochloride

65
Q

Substitute to oxygen

A

p-phenylenediamine dihydrochloride

66
Q

OXIDASE TEST: Reduced state

A

colorless, oxidized = indophenol blue

67
Q

OXIDASE TEST: Positive result

A

formation of BLUE color = Micrococcus

68
Q

OXIDASE TEST: Negative result

A

no change in color = Staphylococcus

69
Q

MODIFIED OXIDASE TEST (MICRODASE)

Uses filter paper disks impregnated with

A

1% tetramethyl-p-phenylenediamine in dimethyl sulfoxide (DMSO)

70
Q

aids in the permeability of cells to the reagent (allows interaction of oxidase and cytochrome C) and stability against auto-oxidation (decreases false positive result)

A

DMSO

71
Q

MODIFIED OXIDASE TEST (MICRODASE): Positive result

A

blue-purple color within 30 seconds = Micrococcus

72
Q

Used to reduce false positive result from metal inoculating loop

A

wooden applicator stick

73
Q

MODIFIED OXIDASE TEST (MICRODASE): Negative result

A

no color change in 30seconds = Staphylococcus

74
Q

(+) atmospheric oxygen

oxidase enzyme + oxidase reagent & cytochrome C = indophenol

When exposed to atmospheric oxygen, the oxidase enzyme reacts with the oxidase reagent and cytochrome C to yield the colored compound, indophenol indicated as [?] on the disc after the bacterial colony is introduced on the disc.

A

blue or purplish blue coloration

75
Q

Medium used in O/F TEST

A

HUGH and LEIFSON’S MEDIUM

76
Q

the only carbohydrate included in the medium

A

GLUCOSE

77
Q

non-glucose utilizer

A

Asaccharolytic/nonsaccharolytic

78
Q

glucose utilizer

A

Saccharolytic

79
Q

turns yellow in acidic pH in O/F test

A

Bromothymol blue/green

80
Q

(pH indicator) for O/F TEST

A

Bromothymol blue/green

81
Q

O/F TEST detects ability of the bacteria to utilize glucose through oxidative process (?), both fermentative and oxidative () or not at all (?)

A

AEROBE
FACULTATIVE ANAEROBE
Asaccharolytic

82
Q

O/F TEST uses two tubes

with mineral oil = ?
without mineral oil = ?

A

(anerobic environment)

aerobic

83
Q

Both tubes turned yellow suggest use of glucose with and without oxygen

A

Facultative anaerobe = Staphylococcus

84
Q

Aerobic tube turns yellow, the anerobic tube remains blue/green suggest use of glucose in presence of oxygen only

A

Obligate aerobe = Micrococcus

85
Q

do not USE glucose, but may utilize other carbohydrate

A

Both remains green/blue

86
Q

One tube for unknown (with Lysostaphin), another tube for negative control (without Lysostaphin)

A

TUBE METHOD

87
Q

10ug of lysostaphin

A

AGAR DISK SENSITIVITY TEST

88
Q

TUBE METHOD: Positive result

A

bacteria is lysed by lysostaphin resulting to clearing (clearing means no growth or death of bacteria) of the sample tube = Staphylococcus

89
Q

TUBE METHOD: Negative result

A

bacteria resist lysis so sample remains turbid = Micrococcus

90
Q

AGAR DISK SENSITIVITY TEST: RESISTANT

A

SUSCEPTIBLE

91
Q

AGAR DISK SENSITIVITY TEST: SUSCEPTIBLE

A

10 to 16 mm = Staphylococcus

92
Q

is one of the synthetic antimicrobial nitrofurans with antiprotozoal and antibacterial activity.

A

Furoxone (furazolidone)

93
Q

Furazolidone binds bacterial DNA which leads to the gradual inhibition of

A

monoamine oxidase

94
Q

FURAZOLIDONE ST: Resistant

A

Zone of inhibition ≤ 9 mm = Micrococcus spp

95
Q

FURAZOLIDONE ST: Sensitive

A

Zone of inhibition > 15 mm = Staphylococcus spp

96
Q

Must be tested for catalase test first; To rule out Streptococcus species

A

BACITRACIN ST

97
Q

BACITRACIN ST is known as

A

TAXO A

98
Q

Due to sensitivity of [?] strep to this antibiotic

A

Group A

99
Q

Uses [?] of Bacitracin

A

0.04U

100
Q

BACITRACIN ST: RESISTANT

A

<10 mm ZOI = Staphylococcus

101
Q

BACITRACIN ST: SUSCEPTIBLE

A

10-20 mm ZOI = Micrococcus

102
Q

Test for bound catalase / “clumping factor”

A

SLIDE COAGULASE TEST

103
Q

clumping will occur because the clumping factor is an [?] which causes cells to bind fibrinogen in plasma

A

adhesin

104
Q

SLIDE COAGULASE TEST

is not a definitive test for

A

S. aureus

105
Q

Negative result still needs to undergo

A

tube coagulase test

106
Q

presence of [?] in negative control invalidates the test

A

autoagglutination

107
Q

possible due to dirty glass slides

A

autoagglutination

108
Q

SLIDE COAGULASE TEST: Positive result

A

clumping within 10s = S. aureus, S. lugdunensis, S. schleiferi

109
Q

SLIDE COAGULASE TEST: Negative result

A

homogenous/ no clumping

110
Q

Around [?] of S. aureus strains test negative

A

15%

111
Q

Test for free coagulase

A

TUBE COAGULASE TEST

112
Q

May act to coat the bacterial cells with fibrin making them resistant to

A

opsonisation and phagocytosis

113
Q

Uses lyophilized EDTA rabbit plasma

A

↑CRF = better clotting

114
Q

Breaks fibrin clot and allow the spread of infection to contiguous tissues

A

Staphylokinase

115
Q

TUBE COAGULASE TEST: Positive result

A

clot/gel formation = S. aureus

116
Q

False positive: TUBE COAGULASE TEST

A

citrate-using organisms such as Pseudomonas species, Serratia marcescens, Enterococcus faecalis, and some strains of Streptococcus will coagulate citrated plasma (EDTA plasma is preferred over citrated plasma)

117
Q

Negative result: TUBE COAGULASE TEST

A

no clot formation = Coagulase negative staphylococcus (CONS)

118
Q

a hydrolytic enzyme that depolymerizes and degrades DNA

A

Deoxyribonuclease

119
Q

Dyes used in DNAse test

A

Methyl green or

Toluidine blue O

120
Q

Positive result: DNAse test

A

clearing around colony = S. aureus

121
Q

Negative result: DNAse test

A

no clearing = CONS

122
Q

allows better visualization of the clearing if no dye is included in the agar

A

HCl

123
Q

inhibitor of DNA gyrase

A

Novobiocin disk (5ug)

124
Q

usually performed on urine isolates (isolated from women of reproductive age group) that are coagulase-negative

A

Novobiocin sensitivity test

125
Q

usually performed on urine isolates (isolated from women of reproductive age group) that are

A

coagulase-negative

126
Q

is second only to E. coli as the most frequent causative organism of uncomplicated urinary tract infections (UTIs)

A

S. saprophyticus

127
Q

RESISTANT: Novobiocin sensitivity test

A

<12mm ZOI = S. saprophyticus

128
Q

SUSCEPTIBLE: Novobiocin sensitivity test

A

> 16mm ZOI S. aureus, S. epidermidis

129
Q

diagnostic to S. saprophyticus with [?], coagulase negative result

A

γ-hemolytic

130
Q

Encapsulated (mucoid colonies)

A

Staphylococcus epidermidis

131
Q

may be positive in the tube test

A

S. Intermedius (dogs)andS. hyicus (pigs)

[6] LABORATORY DIAGNOSIS OF STAPHYLOCOCCUS AND MICROCOCCUS (3 decks)

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