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Microbiology > Unit 2: Gram Positive Cocci > Flashcards

Unit 2: Gram Positive Cocci Flashcards

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1
Q

FREQUENT GPC isolates

A

Staph
Strep
Enterococcus

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2
Q

Why do GPC stain the way they do?

A

Peptidoglycan layer in their cell wall

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3
Q

What is in the cell wall of GPC?

A

Thick peptidoglycan layer

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4
Q

Which part of the gram stain does GPC like?

A

Crystal violet
Iodine

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5
Q

List the steps of Gram Staining

A

Crystal Violet
Iodine
Decolorizer
Safranin

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6
Q

OCCASSIONAL GPC isolates

A

Micrococcus
Strep-look alikes
(Leukonostoc, Gemella, Aerococcus, Pediococcus)

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7
Q

What are the strep lookalikes?

A

Leukonostoc
Gemella
Aerococcus
Pediococcus

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8
Q

What are GPC theoretically susceptible to?

A

Penicillin

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9
Q

General Virulence factors of GPC

A

Toxins
Hemolysins
Capsules
Protein factors
Combination of factors (S. pneumo)

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10
Q

Pathology of GPC in body (what does it do to you?)

A

Pyrogenic (fever)
Swelling
Purulence
Lysins
Tissue invasion (Spreading)

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11
Q

What are diseases caused by GPC

A

Pharyngitis
Abscesses
Scaled Skin Syndrome
Toxic Shock Syndrom
Impetigo (skin infection)
Pneumonia
Bacteremia
Food poisoning
UTI

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12
Q

What genera are in the Micrococcaceae family?

A

Staphylococcus
Micrococcus

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13
Q

What family is Staphylococcus in?

A

Micrococcaceae

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14
Q

Common Strep-like genera

A

Enterococcus

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15
Q

Uncommon strep-like genera

A

Leukonostoc
Gemella
Aerococcus
Pediococcus

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16
Q

What enzyme is produced by Staph?

A

Catalase

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17
Q

What does catalase do?

A

Splits hydrogen peroxide into oxygen and water

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18
Q

What is a positive catalase test?

A

Copious bubbles

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19
Q

How does staphylococcus appear under the microscope?

A

Gram positive cocci in grape like clusters

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20
Q

What do the colonies of a staphylococcus look like?

A

Smooth, raised round
Creamy
White to dirty white
Dollops of cream cheese

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21
Q

What type of hemolysis is seen on the SBA with staphylococci?

A

Some are B hemolytic

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22
Q

Staphylococci are resistant to what test to differentiate it from Micrococcus?

A

Bacitracin

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23
Q

What test differentiates Staphylococcus from Micrococcus? How so?

A

Bacitracin
Staphylococcus RESISTANT to bacitracin
Micrococcus SUSCEPTIBLE to bacitracin

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24
Q

Staphylococcal diseases

A

TSS
Food poisoning
Skin infections
Abscesses
Blood infection
Pneumonia
UTI

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25
Q

What kind of agar is required for Staph ID?

A

Non-fastidious

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26
Q

What kind of non-fastidious agar is used to grow staph?

A

SBA (Trypticase soy agar w/ 5% sheep blood)
Nutrient agar

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27
Q

What plates will not produce staph growth? Why?

A

EMB
MAC
Because they have antibiotics to prevent gram positive growth

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28
Q

How do staph colonies appear?

A

Smooth
Creamy
White-yellow
Maybe B-hemolytic

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29
Q

What test is conducted after catalase?

A

Coagulase

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30
Q

What organisms are Slide positive? (Bound)

A

S. aureus
S. lugdunesnsis
S. schleiferi subs. schleiferi

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31
Q

What organisms are tube coagulase positive? (Free coagulase)

A

S. aureus
S. intermedius
S. pseudintermedius
S. scheliferi subs. coagulans

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32
Q

What is the coagulase test for?

A

Testing ability of organism to clot plasma

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33
Q

What does coagulase pos look like?

A

Clumps

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34
Q

Delayed slide coagulase is indicative of what?

A

S. lugdunensis

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35
Q

What is Novobiocin susceptibility done to accomplish?

A

Distinguishing between CoNS (S. epidermis mainly) and S. saprophyticus

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36
Q

What agars are used for novobiocin susceptibility testing?

A

Mueller Hinton
SBA

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37
Q

What is the method done to conduct Novobiocin testing?

A

0.5 McFarland standard prepared
Lawn plated
5ug disc placed
Incubate overnight

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38
Q

How long is Novobiocin incubated for?

A

Overnight, at least 8 hours

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39
Q

What is a susceptible/resistant Novobiocin result?

A

≤ 16mm = Resistant = S. saprophyticus
≥ 16mm = Susceptible = CoNS (S. epidermis)

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40
Q

What is the most virulent staphylococcal disease?

A

S. aureus

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41
Q

What staph is PYR neg?

A

S. aureus

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42
Q

Where can S. aureus be normal flora in?

A

Carriers in nose

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43
Q

A food worker sneezed onto food, contaminating it, and gave patrons food poisoning. What is the likely pathogen that caused this?

A

S. aureus
(bcz present in nasal passages as a carrier)

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44
Q

What diseases does S. aureus cause

A

TSS
Infected wounds
Food poisoning
Bacteremia

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45
Q

What Staph was formerly thought of as a non-virulent/contaminant

A

S. epidermidis

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46
Q

What staph is now associated with nosocomial infections? Which ones?

A

S. epidermidis
UTIs
Endocarditis

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47
Q

A young, sexually active female presents with a UTI. What is the bug most likely responsible?

A

S. saprophyticus

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48
Q

What bug is most associated with young females and causes UTIs?

A

S. saprophyticus

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49
Q

S. lugdunensis causes what types of issues?

A

Skin and soft tissue infections
Septicemia
Meningitis
Endocarditis

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50
Q

What bug is slide coagulase positive but tube coagulase negative?

A

S. lugdunensis
S. scheliferi

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51
Q

What staph is isolated from dog bites?

A

S. intermedius

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52
Q

What bug is coagulase positive and is isolated from a dog-bite wound

A

S. intermedius

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53
Q

When must you ID to species level?

A

If from a sterile site

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54
Q

If a site is not sterile, how would you report a staphylococcus infection?

A

CoNS

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55
Q

If a staph is resistant to methicillin what is the next step?

A

Test susceptibility to vancomycin

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56
Q

What staph aureus strains have to be AST?

A

All

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57
Q

What bug is normal skin flora and is yellow in color?

A

Micrococcus

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58
Q

Normal flora in micrococcaceae family

A

S. epidermis
Microccocus

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59
Q

How common is micrococcus in relation to staph?

A

Not common

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60
Q

How to distinguish micrococcus from staph?

A

Micrococcus
Bacitracin sus, Oxidase +

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61
Q

Oxidase results for micrococcus?

A

Positive

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62
Q

Furazolidone results Micrococcus vs Staph

A

Micrococcus Furazolidone R
Staph Furazolidone S

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63
Q

Lysostaphin results Micrococcus vs Staph

A

Micrococcus Lysostaphin R
Staphylococcus Lysostaphin S

64
Q

Bacitracin results Micrococcus vs Staph

A

Micrococcus Bacitracin S
Staphylococcus Bacitracin R

65
Q

What genera are GPC in pairs and chains?

A

Streptococci

66
Q

Catalse test results in Strep?

A

Negative

67
Q

How do strep colonies appear on a plate?

A

Convex to umbonate

68
Q

Strep diseases

A

Pharyngitis
Scarlet fever
Newborn sepsis
UTIs
Pneumonia
Bacteremia
Endocarditis

69
Q

Agar required for Strep ID

A

SBA

70
Q

What plates will not grow strep and why?

A

EMB
MAC
Antibiotics prevent GP growth

71
Q

what tests are done to ID strep

A

Catalase Negative
Hemolysis type
Bacitracin or PYR
CAMP or Hippurate Hydrolysis
Optochin or Bile solubility
Bile esculin hydrolysis
Growth in salt broth

72
Q

What is the test for a past GAS infection?

A

ASO

73
Q

What test is confirmation of Strep ID

A

Lancefield antibody kits with antisera to Lancefield groups (A,B,C,D,F,G)

74
Q

B hemolytic strep

A

Groups A, B, C, G
S. Pyogenes (GAS)
S. agalactiae (GBS)
S. dysgalactiae (GCGS)

75
Q

Clinical diseases caused by S. pyogenes

A

Strep throat
Impetigo
Scarlet fever
Sequelae (rheumatic fever, glomerulonephritis)
Invasive infections

76
Q

What Strep group other than A can cause throat infections?

A

GCGS, less common than GAS

77
Q

What causes scarlet fever?

A

GAS infection that causes a rash

78
Q

What sequelae can occur with GAS

A

Rheumatic fever (throat inf)
Glomerulonephritis (skin & throat infection)

79
Q

What invasive infections caused by GAS

A

Necrotizing fasciitis caused by Streptococcal pyogenic exotoxin (SPE)

80
Q

What Strep groups can be a carrier state in some people?

A

GAS - Strep Pyogenes
S. pneumo

81
Q

What antibiotics are used for Strep pyogenes?

A

Penicillin
Clindamyicn or erythromycin in Penicillin allergy

82
Q

Is AST required for strep?

A

No, universally susceptible to penicillin

83
Q

Lab features of GAS

A

ß hemolytic
Pinpoint, umbonate colonies
Large zone of hemolysis
Bacitracin suscpetibility
PYR positive

84
Q

What tests are done to ID GAS?

A

Bacitracin/A Disk (sus)
PYR (pos)

85
Q

Difference between GAS and GBS hemolysis?

A

GAS obvious
GBS not obvious

86
Q

What strep causes infection in pregnant females that can cause abortions?

A

S. agalactiae

87
Q

What populations are susceptible to GBS?

A

Newborns (septicemia, meningitis)
Elderly

88
Q

What strep is normal flora in the vaginal/GI tract in females?

A

S. agalactiae GBS

89
Q

All pregnant females are cultured/tested for this in their last trimester

A

S. agalactiae

90
Q

What bug has a major emphasis for all infectious disease personnel to prevent disease in newborns ?

A

S. agalactiae

91
Q

Where is specimen collected for S. agalactiae?

A

Vaginal and rectal swabs
BOTH!

92
Q

Where is S. agalactiae grown?

A

SBA
Selective media
Enrichment (LIM) broth

93
Q

Lab features of S. agalactiae

A

B hemolytic (10% nonhemolytic)
Flatter colony growth than GAS
Hemolysis zone smaller than GAS
CAMP positive
Hippurate hydrolysis positive

94
Q

What % of S. agalactiae is non B hemolytic?

A

10%

95
Q

IS AST necessary on S. agalactiae?

A

No, universally susceptible to penicillin

96
Q

What if patient is allergic to penicillin w/ S. agalactiae infection?

A

Must test AST non B-lactam antibiotics for susceptibility
Shown resistance to erythromycin

97
Q

S. dysgalactiae clinical disease

A

Strep throat in teens and young adults
not common
B hemolytic

98
Q

A 16 year old presents with strep throat. What could be the bug?

A

S. dysgalactiae

99
Q

difference in strep throat by age

A

GAS - children
GCGS - teens & young adults

100
Q

Alpha hemolytic streps

A

Viridans streptococci
S. pneumoniae
Some GDS
Some Enterococci

101
Q

Strep pneumo clinical disease

A

Pneumonia
middle ear infections
meningitis
septicemia

102
Q

What lance field group is S. pneumoniae in?

A

S. pneumo has no lancefield grouping

103
Q

What characteristic does Strep pneumo have?

A

Polysaccharide capsule that causes major virulence factor

104
Q

What helps to serotype strains of S. pneumo?

A

Its polysaccharide capsule

105
Q

Which strep has a polysaccharide capsule?

A

S. pneumo

106
Q

How does S. pneumo appear on a plate?

A

Alpha-hemolytic
Muscoid, shiny or INDENTED CENTER

107
Q

What form of flora can S. pneumo be inside of a person?

A

Carrier

108
Q

Lab features of S. pneumo

A

Optochin (p disc) susceptible
Bile soluble
GPC diplococci lancet shaped

109
Q

What is a positive P disk?

A

> 14mm pos = s. pneumo

110
Q

How does S. pneumo look under the microscope? Where is the swab collected from?

A

GPC
Diplococci
Lancet shaped
Collected from sputum

111
Q

Which is not an official taxonomic group of Strep?

A

Viridans strep

112
Q

A sputum sample is gram stained and gram positive diplococci are seen. what could this be

A

S. pneumoniae

113
Q

What is viridian strep?

A

Phrase for alpha hemolytic strep that is not sensitive to optochin

114
Q

Alpha hemolytic
Resistant to optochin

A

Viridians strep

115
Q

Species of viridians strep

A

mutans
salivarius
sanguis
mitis
anginosus

116
Q

What state is viridians strep found in?

A

Normal flora of the Upper Respiratory Tract

117
Q

What clinical infections are caused by viridian strep

A

Subacute bacterial endocarditis
Wound infections
Dental cavities

118
Q

When is Viridans strep identified to species level?

A

Only when serious infection from normally sterile site

119
Q

Lab features of Viridans strep

A

Alpha hemolytic, occasionally gamma
Colony raised and umbonate
Resistant to optochin
Bile insoluble

120
Q

GDS is normal flora of

A

The bowel

121
Q

Clinical diseases of the GDS

A

UTIs
Abscessess
Endocarditis

122
Q

Lab features of GDS

A

Y hemolytic, sometimes a or B
Grows in bile and hydrolyzes sculpin (BE pos)
No growth in 6.5% salt broth
PYR Negative

123
Q

Antibiotics for GDS

A

Penicillin
no AST required

124
Q

Enterococcus is normal flora of what

A

The bowel

125
Q

Clinical diseases of enterococcus

A

UTI
Wound infections
endocarditis

126
Q

Antibiotics for enterococcus

A

VERY resistant to antibiotics

127
Q

Lab features of enterococcus

A

Raised and umbonate colony, resembles hat
usually Y hemolytic, SOMETIMES a or B
Bile esculin positive
Growth in salt broth (cloudy &/or color change)
PYR positive (GAS also PYR pos!)
Often ID’d to species level

128
Q

Difference between GDS and Enterococcus?

A

Both BE pos
GDS no growth in salt broth
Enterococcus growth in salt broth

129
Q

What two streps are PYR positive?

A

GAS
Enterococcus

130
Q

Growth in salt broth.. what could this be?

A

Enterococcus

131
Q

black color in BE.. what could this be?

A

GDS or Enterococcus

132
Q

What form of flora is nutritionally variant strep found in?

A

Normal flora of the mouth

133
Q

What does nutritionally variant strep need to grow?

A

Cysteine and Vitamin B6

134
Q

Does nutritionally variant strep grow on SBA?

A

No, in blood culture tubes

135
Q

What diseases can nutritionally variant strep cause?

A

Endocarditis
Otitis media

136
Q

GPC growth from blood culture tube
No growth on SBA
What could this be?

A

Nutritionally variant strep

137
Q

What bug can satellite around S. aureus?

A

Nutritionally Variant Strep

138
Q

What plate will Nutritionally Variant Strep grow on?

A

Chocolate agar

139
Q

How can you get NVS to grow on SBA?

A

Streak S. aureus and it will satellite around it

140
Q

What is NVS now named?

A

Abiotrophia spp.
Granulicatella spp.

141
Q

What strep like organisms are all resistant to vancomycin

A

Leoconostoc and pediococcus

142
Q

What strep like organisms are all sus to vancomycin

A

Aerococcus and gamella

143
Q

How often are strep like organisms isolated

A

Less commonly

144
Q

What do strep like organisms cause

A

Endocarditis
Septicemia

145
Q

LAP testing for all strep

A

Pos

146
Q

LAP testing for Enterococci

A

Pos

147
Q

LAP testing for Pediococcus

A

Pos

148
Q

Lap testing for leuconostoc

A

Neg

149
Q

LAP testing for aerococcus

A

Neg

150
Q

What does it mean if you have a bug that is LAP neg

A

Is NOT strep or enterococcus

151
Q

Which bugs have PYR enzyme?

A

S. pyogenes
Enterococcus sp.
Other GPC

152
Q

What does PYR do?

A

Hydrolyzes a substrate to alpha naphthylamine

153
Q

What is added to PYR?

A

Cinnamaldehyde reagent

154
Q

Which test is most specific for Group A?

A

PYR

155
Q
A

Microbiology (5 decks)

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