Unit 2: Gram Positive Cocci Flashcards
(155 cards)
1
Q
FREQUENT GPC isolates
A
Staph
Strep
Enterococcus
2
Q
Why do GPC stain the way they do?
A
Peptidoglycan layer in their cell wall
3
Q
What is in the cell wall of GPC?
A
Thick peptidoglycan layer
4
Q
Which part of the gram stain does GPC like?
A
Crystal violet
Iodine
5
Q
List the steps of Gram Staining
A
Crystal Violet
Iodine
Decolorizer
Safranin
6
Q
OCCASSIONAL GPC isolates
A
Micrococcus
Strep-look alikes
(Leukonostoc, Gemella, Aerococcus, Pediococcus)
7
Q
What are the strep lookalikes?
A
Leukonostoc
Gemella
Aerococcus
Pediococcus
8
Q
What are GPC theoretically susceptible to?
A
Penicillin
9
Q
General Virulence factors of GPC
A
Toxins
Hemolysins
Capsules
Protein factors
Combination of factors (S. pneumo)
10
Q
Pathology of GPC in body (what does it do to you?)
A
Pyrogenic (fever)
Swelling
Purulence
Lysins
Tissue invasion (Spreading)
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
12
Q
What genera are in the Micrococcaceae family?
A
Staphylococcus
Micrococcus
13
Q
What family is Staphylococcus in?
A
Micrococcaceae
14
Q
Common Strep-like genera
A
Enterococcus
15
Q
Uncommon strep-like genera
A
Leukonostoc
Gemella
Aerococcus
Pediococcus
16
Q
What enzyme is produced by Staph?
A
Catalase
17
Q
What does catalase do?
A
Splits hydrogen peroxide into oxygen and water
18
Q
What is a positive catalase test?
A
Copious bubbles
19
Q
How does staphylococcus appear under the microscope?
A
Gram positive cocci in grape like clusters
20
Q
What do the colonies of a staphylococcus look like?
A
Smooth, raised round
Creamy
White to dirty white
Dollops of cream cheese
21
Q
What type of hemolysis is seen on the SBA with staphylococci?
A
Some are B hemolytic
22
Q
Staphylococci are resistant to what test to differentiate it from Micrococcus?
A
Bacitracin
23
Q
What test differentiates Staphylococcus from Micrococcus? How so?
A
Bacitracin
Staphylococcus RESISTANT to bacitracin
Micrococcus SUSCEPTIBLE to bacitracin
24
Q
Staphylococcal diseases
A
TSS
Food poisoning
Skin infections
Abscesses
Blood infection
Pneumonia
UTI
25
What kind of agar is required for Staph ID?
Non-fastidious
26
What kind of non-fastidious agar is used to grow staph?
SBA (Trypticase soy agar w/ 5% sheep blood)
Nutrient agar
27
What plates will not produce staph growth? Why?
EMB
MAC
Because they have antibiotics to prevent gram positive growth
28
How do staph colonies appear?
Smooth
Creamy
White-yellow
Maybe B-hemolytic
29
What test is conducted after catalase?
Coagulase
30
What organisms are Slide positive? (Bound)
S. aureus
S. lugdunesnsis
S. schleiferi subs. schleiferi
31
What organisms are tube coagulase positive? (Free coagulase)
S. aureus
S. intermedius
S. pseudintermedius
S. scheliferi subs. coagulans
32
What is the coagulase test for?
Testing ability of organism to clot plasma
33
What does coagulase pos look like?
Clumps
34
Delayed slide coagulase is indicative of what?
S. lugdunensis
35
What is Novobiocin susceptibility done to accomplish?
Distinguishing between CoNS (S. epidermis mainly) and S. saprophyticus
36
What agars are used for novobiocin susceptibility testing?
Mueller Hinton
SBA
37
What is the method done to conduct Novobiocin testing?
0.5 McFarland standard prepared
Lawn plated
5ug disc placed
Incubate overnight
38
How long is Novobiocin incubated for?
Overnight, at least 8 hours
39
What is a susceptible/resistant Novobiocin result?
≤ 16mm = Resistant = S. saprophyticus
≥ 16mm = Susceptible = CoNS (S. epidermis)
40
What is the most virulent staphylococcal disease?
S. aureus
41
What staph is PYR neg?
S. aureus
42
Where can S. aureus be normal flora in?
Carriers in nose
43
A food worker sneezed onto food, contaminating it, and gave patrons food poisoning. What is the likely pathogen that caused this?
S. aureus
(bcz present in nasal passages as a carrier)
44
What diseases does S. aureus cause
TSS
Infected wounds
Food poisoning
Bacteremia
45
What Staph was formerly thought of as a non-virulent/contaminant
S. epidermidis
46
What staph is now associated with nosocomial infections? Which ones?
S. epidermidis
UTIs
Endocarditis
47
A young, sexually active female presents with a UTI. What is the bug most likely responsible?
S. saprophyticus
48
What bug is most associated with young females and causes UTIs?
S. saprophyticus
49
S. lugdunensis causes what types of issues?
Skin and soft tissue infections
Septicemia
Meningitis
Endocarditis
50
What bug is slide coagulase positive but tube coagulase negative?
S. lugdunensis
S. scheliferi
51
What staph is isolated from dog bites?
S. intermedius
52
What bug is coagulase positive and is isolated from a dog-bite wound
S. intermedius
53
When must you ID to species level?
If from a sterile site
54
If a site is not sterile, how would you report a staphylococcus infection?
CoNS
55
If a staph is resistant to methicillin what is the next step?
Test susceptibility to vancomycin
56
What staph aureus strains have to be AST?
All
57
What bug is normal skin flora and is yellow in color?
Micrococcus
58
Normal flora in micrococcaceae family
S. epidermis
Microccocus
59
How common is micrococcus in relation to staph?
Not common
60
How to distinguish micrococcus from staph?
Micrococcus
Bacitracin sus, Oxidase +
61
Oxidase results for micrococcus?
Positive
62
Furazolidone results Micrococcus vs Staph
Micrococcus Furazolidone R
Staph Furazolidone S
63
Lysostaphin results Micrococcus vs Staph
Micrococcus Lysostaphin R
Staphylococcus Lysostaphin S
64
Bacitracin results Micrococcus vs Staph
Micrococcus Bacitracin S
Staphylococcus Bacitracin R
65
What genera are GPC in pairs and chains?
Streptococci
66
Catalse test results in Strep?
Negative
67
How do strep colonies appear on a plate?
Convex to umbonate
68
Strep diseases
Pharyngitis
Scarlet fever
Newborn sepsis
UTIs
Pneumonia
Bacteremia
Endocarditis
69
Agar required for Strep ID
SBA
70
What plates will not grow strep and why?
EMB
MAC
Antibiotics prevent GP growth
71
what tests are done to ID strep
Catalase Negative
Hemolysis type
Bacitracin or PYR
CAMP or Hippurate Hydrolysis
Optochin or Bile solubility
Bile esculin hydrolysis
Growth in salt broth
72
What is the test for a past GAS infection?
ASO
73
What test is confirmation of Strep ID
Lancefield antibody kits with antisera to Lancefield groups (A,B,C,D,F,G)
74
B hemolytic strep
Groups A, B, C, G
S. Pyogenes (GAS)
S. agalactiae (GBS)
S. dysgalactiae (GCGS)
75
Clinical diseases caused by S. pyogenes
Strep throat
Impetigo
Scarlet fever
Sequelae (rheumatic fever, glomerulonephritis)
Invasive infections
76
What Strep group other than A can cause throat infections?
GCGS, less common than GAS
77
What causes scarlet fever?
GAS infection that causes a rash
78
What sequelae can occur with GAS
Rheumatic fever (throat inf)
Glomerulonephritis (skin & throat infection)
79
What invasive infections caused by GAS
Necrotizing fasciitis caused by Streptococcal pyogenic exotoxin (SPE)
80
What Strep groups can be a carrier state in some people?
GAS - Strep Pyogenes
S. pneumo
81
What antibiotics are used for Strep pyogenes?
Penicillin
Clindamyicn or erythromycin in Penicillin allergy
82
Is AST required for strep?
No, universally susceptible to penicillin
83
Lab features of GAS
ß hemolytic
Pinpoint, umbonate colonies
Large zone of hemolysis
Bacitracin suscpetibility
PYR positive
84
What tests are done to ID GAS?
Bacitracin/A Disk (sus)
PYR (pos)
85
Difference between GAS and GBS hemolysis?
GAS obvious
GBS not obvious
86
What strep causes infection in pregnant females that can cause abortions?
S. agalactiae
87
What populations are susceptible to GBS?
Newborns (septicemia, meningitis)
Elderly
88
What strep is normal flora in the vaginal/GI tract in females?
S. agalactiae GBS
89
All pregnant females are cultured/tested for this in their last trimester
S. agalactiae
90
What bug has a major emphasis for all infectious disease personnel to prevent disease in newborns ?
S. agalactiae
91
Where is specimen collected for S. agalactiae?
Vaginal and rectal swabs
BOTH!
92
Where is S. agalactiae grown?
SBA
Selective media
Enrichment (LIM) broth
93
Lab features of S. agalactiae
B hemolytic (10% nonhemolytic)
Flatter colony growth than GAS
Hemolysis zone smaller than GAS
CAMP positive
Hippurate hydrolysis positive
94
What % of S. agalactiae is non B hemolytic?
10%
95
IS AST necessary on S. agalactiae?
No, universally susceptible to penicillin
96
What if patient is allergic to penicillin w/ S. agalactiae infection?
Must test AST non B-lactam antibiotics for susceptibility
Shown resistance to erythromycin
97
S. dysgalactiae clinical disease
Strep throat in teens and young adults
not common
B hemolytic
98
A 16 year old presents with strep throat. What could be the bug?
S. dysgalactiae
99
difference in strep throat by age
GAS - children
GCGS - teens & young adults
100
Alpha hemolytic streps
Viridans streptococci
S. pneumoniae
Some GDS
Some Enterococci
101
Strep pneumo clinical disease
Pneumonia
middle ear infections
meningitis
septicemia
102
What lance field group is S. pneumoniae in?
S. pneumo has no lancefield grouping
103
What characteristic does Strep pneumo have?
Polysaccharide capsule that causes major virulence factor
104
What helps to serotype strains of S. pneumo?
Its polysaccharide capsule
105
Which strep has a polysaccharide capsule?
S. pneumo
106
How does S. pneumo appear on a plate?
Alpha-hemolytic
Muscoid, shiny or INDENTED CENTER
107
What form of flora can S. pneumo be inside of a person?
Carrier
108
Lab features of S. pneumo
Optochin (p disc) susceptible
Bile soluble
GPC diplococci lancet shaped
109
What is a positive P disk?
>14mm pos = s. pneumo
110
How does S. pneumo look under the microscope? Where is the swab collected from?
GPC
Diplococci
Lancet shaped
Collected from sputum
111
Which is not an official taxonomic group of Strep?
Viridans strep
112
A sputum sample is gram stained and gram positive diplococci are seen. what could this be
S. pneumoniae
113
What is viridian strep?
Phrase for alpha hemolytic strep that is not sensitive to optochin
114
Alpha hemolytic
Resistant to optochin
Viridians strep
115
Species of viridians strep
mutans
salivarius
sanguis
mitis
anginosus
116
What state is viridians strep found in?
Normal flora of the Upper Respiratory Tract
117
What clinical infections are caused by viridian strep
Subacute bacterial endocarditis
Wound infections
Dental cavities
118
When is Viridans strep identified to species level?
Only when serious infection from normally sterile site
119
Lab features of Viridans strep
Alpha hemolytic, occasionally gamma
Colony raised and umbonate
Resistant to optochin
Bile insoluble
120
GDS is normal flora of
The bowel
121
Clinical diseases of the GDS
UTIs
Abscessess
Endocarditis
122
Lab features of GDS
Y hemolytic, sometimes a or B
Grows in bile and hydrolyzes sculpin (BE pos)
No growth in 6.5% salt broth
PYR Negative
123
Antibiotics for GDS
Penicillin
no AST required
124
Enterococcus is normal flora of what
The bowel
125
Clinical diseases of enterococcus
UTI
Wound infections
endocarditis
126
Antibiotics for enterococcus
VERY resistant to antibiotics
127
Lab features of enterococcus
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
Difference between GDS and Enterococcus?
Both BE pos
GDS no growth in salt broth
Enterococcus growth in salt broth
129
What two streps are PYR positive?
GAS
Enterococcus
130
Growth in salt broth.. what could this be?
Enterococcus
131
black color in BE.. what could this be?
GDS or Enterococcus
132
What form of flora is nutritionally variant strep found in?
Normal flora of the mouth
133
What does nutritionally variant strep need to grow?
Cysteine and Vitamin B6
134
Does nutritionally variant strep grow on SBA?
No, in blood culture tubes
135
What diseases can nutritionally variant strep cause?
Endocarditis
Otitis media
136
GPC growth from blood culture tube
No growth on SBA
What could this be?
Nutritionally variant strep
137
What bug can satellite around S. aureus?
Nutritionally Variant Strep
138
What plate will Nutritionally Variant Strep grow on?
Chocolate agar
139
How can you get NVS to grow on SBA?
Streak S. aureus and it will satellite around it
140
What is NVS now named?
Abiotrophia spp.
Granulicatella spp.
141
What strep like organisms are all resistant to vancomycin
Leoconostoc and pediococcus
142
What strep like organisms are all sus to vancomycin
Aerococcus and gamella
143
How often are strep like organisms isolated
Less commonly
144
What do strep like organisms cause
Endocarditis
Septicemia
145
LAP testing for all strep
Pos
146
LAP testing for Enterococci
Pos
147
LAP testing for Pediococcus
Pos
148
Lap testing for leuconostoc
Neg
149
LAP testing for aerococcus
Neg
150
What does it mean if you have a bug that is LAP neg
Is NOT strep or enterococcus
151
Which bugs have PYR enzyme?
S. pyogenes
Enterococcus sp.
Other GPC
152
What does PYR do?
Hydrolyzes a substrate to alpha naphthylamine
153
What is added to PYR?
Cinnamaldehyde reagent
154
Which test is most specific for Group A?
PYR
155
