Staphylococcus Flashcards
1
Q
Staphylococcus spp. belong to the family ___________.
A
Staphylococcaceae
2
Q
Staphylococcus spp. is combined with the _________, __________, and _________ into the order Bacillales.
A
Bacillaceae, Planococcaceae, and Listeriaceae
3
Q
Staphylococcus spp. has now been combined with the Bacillaceae, Planococcaceae, and Listeriaceae into the order _________.
A
Bacillales or Bacillacea
4
Q
In terms of biochemical examination, majority of the Staphylococcus spp. are __________.
A
Catalase Positive
5
Q
Staphylococcus spp. can also be ________, but some can be __________.
A
Coagulase Positive, some are Coagulase Negative
6
Q
What do we call the Staphylococcus spp. that are COAGULASE NEGATIVE?
A
CoNS - Coagulase Negative Staphylococcus
7
Q
Describe the appearance of Staphylococcus spp.
A
Gram Positive cocci in singly, in pairs, and in GRAPE-LIKE clusters
8
Q
Staphylococcus spp. are commonly known for their _________ appearance.
A
Grape-like
9
Q
Which bacteria are often mistaken for Staphylococcus?
A
MNEMONIC: ARA
- Aerococcus spp.
- Rothia mucillaginosa
- Alloiococcus otitidis
10
Q
Why is ARA mistaken for staphylococcus?
A
Because they are all Gram Positive cocci
11
Q
staphylococcus is a _______ of the human skin and mucous membrane.
A
Normal Flora
12
Q
staphylococcus is a normal flora of the ________.
A
Human Skin and Mucous Membrane
13
Q
Aside from staphylococcus, what are other GRAM POSITIVE normal flora?
A
- Micrococcus spp.
- Kytococcus spp.
- Kocuria spp.
14
Q
Staphylococcaceae resembles the family ___________.
A
Micrococcaceae
15
Q
Microccocaceae are _________ and __________.
A
Catalase Positive and Coagulase Negative
16
Q
Describe the appearance of Micrococcus spp.
A
Gram Positive cocci in pairs, TETRADS and in irregular clusters.
17
Q
Describe pigment of the colonies of Micrococcus spp.
A
Yellow Pigment
18
Q
Alloiococcus otitidis is recovered from _________.
A
Human middle ear fluid
19
Q
How many species are there within the genus Staphylococcus?
A
39
20
Q
How many subspecies are there within the genus Staphylococcus?
A
21
21
Q
What is the result of the Modified Oxidase (Microdase) Test in micrococci?
A
Positive (+)
22
Q
What is the result of the Modified Oxidase (Microdase) Test in staphylococci?
A
Negative (-)
23
Q
Anaerobic Acid Production is also called ________.
A
Fermentation
24
Q
What is the result of the Anaerobic Acid Production from glucose (fermentation) in staphylococci?
A
Positive (+)
25
___________ are fermenters.
staphylococci
26
What is the result of the **Anaerobic Acid Production from glucose** *(fermentation)* in micrococci?
Negative (-)
27
__________ are oxidizers.
micrococci
28
What is the aerotolerance of stapylococci?
Facultative Anaerobes
29
What is the aerotolerance of micrococci?
Obligate Aerobes
30
What is the result of the **Anaerobic Acid Production from glycerol** in the presence of erythromycin *(fermentation)* in staphylococci?
Positive (+)
31
What is the result of the **Anaerobic Acid Production from glycerol** in the presence of erythromycin *(fermentation)* in micrococci?
Negative (-)
32
Furoxone-Tween 80 oil-red O agar is an example of __________.
Selective Media
33
Which is the inhibitor in the Furoxone-Tween 80 oil-red O agar?
Furoxone
34
What is the result of the growth on **Furoxone-Tween 80 oil-red O agar** in staphylococci?
Negative (-) as it is inhibited by Furoxone
35
What is the result of the growth on **Furoxone-Tween 80 oil-red O agar** in micrococci?
Positive (+)
36
It means that the bacterium is not inhibited by the antibiotic.
Resistant
37
It means that the bacterium is inhibited by the antibiotic.
Susceptible/Sensitive
38
**Resistance to bacitracin** (0.04 U) of staphylococci
Resistant *(not inhibited by bacitracin)*
39
**Resistance to bacitracin** (0.04 U) of micrococci
Susceptible *(inhibited by bacitracin)*
40
**Resistance to lysosome** (50-mg disk) of staphylococci
Resistant *(not inhibited by lysosome)*
41
**Resistance to lysosome** (50-mg disk) of micrococci
Susceptible *(inhibited by lysosome)*
42
**Resistance to lysostaphin** (200 ug/mL) of staphylococci
Susceptible *(inhibited by lysostaphin)*
43
**Resistance to lysostaphin** (200 ug/mL) of micrococci
Resistant *(not inhibited by lysostaphin)*
44
All micrococci are OBLIGATE AEROBES except _________.
**MNEMONIC:** KRIVA
- *Micrococcus **kri**stinae*
- *Micrococcus **va**rians*
45
*Micrococcus kristinae* and *Micrococcus varians* are both _________.
Facultative Anaerobes (fermenters)
46
All staphylococci are NEGATIVE in the MICRODASE TEST except _________.
**MNEMONIC:** SCLEVI CASE
- *Staphylococcus **sc**iuri*
- *Staphylococcus **le**ntus*
- *Staphylococcus **vi**tulus*
- *Macrococcus **case**olyticus*
47
Enumerate examples of staphylococci that are positive in the Microdase Test.
**MNEMONIC:** SCLEVI CASE
- *Staphylococcus **sc**iuri*
- *Staphylococcus **le**ntus*
- *Staphylococcus **vi**tulus*
- *Macrococcus **case**olyticus*
48
rothia result in Catalase Test
+/-
49
aerococcus result in Catalase Test
-
50
enterococcus result in Catalase Test
-
51
rothia result in Microdase Test
-
52
aerococcus result in Microdase Test
-
53
enterococcus result in Microdase Test
-
54
Aerotolerance of rothia
Facultative Anaerobe
55
Aerotolerance of aerococcus
Facultative Anaerobe
56
Aerotolerance of enterococcus
Facultative Anaerobe
57
**Resistance to bacitracin** (0.04 U) of rothia
Resistant or Susceptible
58
**Resistance to bacitracin** (0.04 U) of aerococcus
Susceptible
59
**Resistance to bacitracin** (0.04 U) of enterococcus
Resistant
60
**Resistance to furazolidone** (100 ug) of staphylococci
Susceptible
61
**Resistance to furazolidone** (100 ug) of micrococci
Resistant
62
**Resistance to furazolidone** (100 ug) of rothia
Resistant or Susceptible
63
**Resistance to furazolidone** (100 ug) of aerococcus
Susceptible
64
**Resistance to furazolidone** (100 ug) of enterococcus
Susceptible
65
**Resistance to lysostaphin** (200 ug/mL) of rothia
Resistant
66
**Resistance to lysostaphin** (200 ug/mL) of aerococcus
Resistant
67
**Resistance to lysostaphin** (200 ug/mL) of enterococcus
Resistant
68
Staphylococcaceae came from the Greek word ______.
Staphle
69
Staphle means _________.
Bunches of Grapes
70
**TRUE OR FALSE.**
staphylococci are motile
False
71
**TRUE OR FALSE.**
staphylococci are non-spore forming
True
72
**TRUE OR FALSE.**
*Staphylococcus* spp. are aerobic
True (some)
73
Which strains of staphylococci are obligate anaerobes, and catalase negative?
- *Staphylococcus saccharolyticus*
- *Staphylococcus aureus* subsp. *anaerobius*
74
What is the standard size of staphylococci?
Medium (4 to 8 mm)
75
Describe the color of staphylococci colonies
Cream-colored (common), white or rarely light gold (golden yellow)
76
Describe the texture of staphylococci colonies
Buttery-looking
77
**TRUE OR FALSE.**
Generally, staphylococci are fastidious.
False
78
Fastidious staphylococci requirements:
CO2, hemin, menadione, with at least 48 hours of incubation
79
These are organisms which are capable of developing a polysaccharide that appears as a slime layer.
- *Staphylococcus aureus*
- *Staphylococcus epidermidis*
80
The polysaccharide layer of *S. aureus* and *S. epidermidis* allows them to form a _______.
Biofilm
81
What is the purpose of biofilm in *S. aureus* and *S. epidermidis*?
To allow them to attach to inorganic surfaces, and protect against or overcome antibiotic activities.
82
Enumerate the sites where *Staphylococcus aureus* is found.
- Anterior nares
- Nasopharynx
- Perineal area
- Skin
- Colonizer of mucosa
83
Boil or Pigsa is medically known as _________.
Furuncle
84
A cutaneous infection caused by *S. aureus* which has systemic manifestations.
Carbuncle
85
A cutaneous infection caused by *S. aureus* which is characterized by a large pustule with erythema.
Bullous Impetigo
86
Enumerate the infections caused by *Staphylococcus aureus*.
- Cutaneous infections (folliculitis, furuncles, carbuncles, bullous impetigo)
- Food Poisoning
- Scalded Skin Syndrome (SSS)
- Toxic Shock Syndrome (TSS)
- Toxic Epidermal Necrolysis (TEN)
87
Enumerate the infections caused by *Staphylococcus epidermidis*.
Nosocomial Infections
88
Enumerate the sites where *Staphylococcus haemolyticus* is found.
- Skin
- Mucous membranes
89
Enumerate the infections caused by *Staphylococcus haemolyticus*.
- Wound
- Septicemia
- UTIs
- Native Valve Infections
90
Enumerate the infections caused by *Staphylococcus lugdunensis*.
- Catheter-related bacteremia
- Endocarditis
91
Enumerate the infections caused by *Staphylococcus saprophyticus*.
UTI (in adolescent girls and young women)
92
Enumerate the sites where *Staphylococcus saprophyticus* is found.
- Skin
- Genitourinary tract
- Mucosa
93
Enumerate the sites where *Micrococcus* spp.,*Kytococcus* spp., and *Kocuria* spp. are found.
- Skin
- Mucosa
- Oropharynx
94
Enterotoxins are serologically grouped into groups _________.
A-E and G-J
95
What are the three infections associated with Enterotoxins?
- Food Poisoning
- Toxic Shock Syndrome
- Pseudomembranous Enterocolitis
96
# Enterotoxins
Food poisoning is caused by ________.
Enterotoxin Groups A-E
| Mahon: A, B, D
97
How can we determine if food poisoning is caused by the *Staphylococcus aureus* bacterium?
If the patient developed **gastrointestinal symptoms** such as:
- Vomiting
- Stomach ache
- Diarrhea
within **2 to 6 hours after eating contaminated food**
98
How can we determine if food poisoning is caused by a virus?
If the incubation period or manifestation of symptoms is longer.
99
# Enterotoxins
Toxic Shock Syndrome is caused by __________.
Enterotoxin Groups B, C, G, I
100
# Enterotoxins
Pseudomembranous enterocolitis is caused by _________.
Enterotoxin Group B
101
How can you acquire pseudomembranous enterocolitis?
By consuming contaminated milk products
102
Enterotoxins are stable at __________.
100 C for 30 minutes
103
How can you get rid of enterotoxins?
By heating them for more than 100 C for more than 30 minutes
104
A virulence factor of *Staphylococcus aureus* characterized by **desquamation of the skin**.
Toxic Shock Syndrome Toxin-1 (TSS)
105
Toxic Shock Syndrome Toxin-1 (TSS) is previously known as ___________.
Enterotoxin F
106
Toxic Shock Syndrome Toxin-1 (TSS) is also known as __________.
Pyrogenic Exotoxin C
107
What are the systemic effects of Toxic Shock Syndrome Toxin-1 (TSS)?
Manifestation of **fever** which can lead to **hypotension**, which can result to **shock** and/or **death**.
108
What happens to the plasma volume when one has hypotension?
Decreases
109
Who are the people commonly affected by Toxic Shock Syndrome Toxin-1 (TSS)?
Women wearing tampons during menstruation
110
Exfoliative Toxin is also known as ___________.
Epidermolytic Toxin A & B
111
Exfoliative toxin is a _________ which splits the intracellular bridges of the epidermis.
Serine protease
112
What does the exfoliative toxin (serine protease) do?
Split the intracellular bridges of the epidermis which causes the skin to slough off excessively and appear as burnt-like skin.
113
Exfoliative toxin causes __________.
Staphylococcal Scalded Skin Syndrome
114
Staphylococcal Scalded Skin Syndrome is also known as ________.
Ritter Disease
115
Exfoliative toxin is the causative agent or virulence factor associated with _________.
Bullous Impetigo
116
___________ is the causative agent or virulence factor associated with bullous impetigo.
Exfoliative Toxin
117
These are extracellular proteins that affect the RBCs and WBCs.
Cytolytic Toxin or Cytotoxin
118
_________ targets the red blood cells (RBCs).
Hemolysin
119
_________ targets the white blood cells (WBCS).
Leukocidins
120
Hemolysins for *Staphylococcus aureus*
Alpha, Beta, Gamma, and Delta
121
It is characterized by the disruption of smooth muscle in the blood vessels, and its toxicity to erythrocytes, leukocytes, hepatocytes, and platelets.
α-hemolysin
122
α-hemolysin is toxic to ________.
- Erythrocytes
- Leukocytes
- Hepatocytes
- Platelets
123
It acts on sphingomyelin in the plasma membrane of the RBCs.
β-hemolysin
124
β-hemolysin is also known as _______.
Sphingomyelinase C or "hot-cold lysin"
125
Why is β-hemolysin also called as **"hot-cold lysin"**?
Because its hemolytic activity is enhanced upon incubation at 37 C (hot) and subsequently at 4 C (cold)
126
It is utilized as a known factor in CAMP test.
β-hemolysin
127
β-hemolysin is utilized as a known factor in _________.
CAMP Test
128
CAMP test is used for _______.
Identification of *Streptococcus agalactiae*
129
CAMP stands for _______.
**C**hristie, **A**tkins, **M**unch-**P**etersen
130
__________ is less toxic than α-hemolysin or β-hemolysin.
δ-hemolysin
131
The following bacteria exhibits δ-hemolysin:
- *Staphylococcus aureus*
- *Staphylococcus epidermidis*
- *Staphylococcus haemolyticus*
132
__________ functions with Panton-Valentine Leucocidin (PVL).
γ-hemolysin
133
Panton-Valentine Leucocidin (PVL) targets the _________.
Polymorphonuclear Cells (PMN)
134
It is an exotoxin lethal to polymorphonuclear cells (PMS).
Panton-Valentine Leucocidin (PVL)
135
What does Panton-Valentine Leucocidin (PVL) do to phagocytes?
Suppress
136
Panton-Valentine Leucocidin (PVL) is associated with __________.
Severe cutaneous infections and necrotizing pneumonia
137
Panton-Valentine Leucocidin (PVL) is often associated with __________.
Community-acquired staphylococcal infections
138
What are the enzymes produced by staphylococci?
Coagulase, Protease, Hyaluronidase, and Lipase
139
Staphylocoagulase is also known as _________.
Free coagulase
140
An enzyme produced by staphylococci that is known to be a spreading factor.
Hyaluronidase
141
How does hyaluronidase act as a spreading factor?
It hydrolyzes the hyaluronic acid in the intracellular ground substance in the connective tissues, permitting the spread of bacteria during infection.
142
Lipase is produced by both ___________.
Coagulase Positive and CoNS
143
________ acts on lipids present on the surface of the skin.
Lipase
144
Protein A is found in the _________.
Cell wall
145
A virulence factor of staphylococci that is found in the cell wall.
Protein A
146
________ binds to the Fc portion of immunoglobulin G .
Protein A
147
Aside from binding to the Fc portion of IgG, what are the other activities that Protein A do?
Block phagocytosis and inhibit the action of IgG
148
A virulence factor of staphylococci that activates complement, IL-1, chemotactic to PMNs.
Peptidoglycan
149
A virulence factor of staphylococci that mediates binding to fibronectin.
Teichoic Acid
150
Enumerate the workflow in performing a laboratory test.
1. Specimen Collection
2. Direct Microscopic Examination
3. Culture
4. Macroscopic and Microscopic Examination
5. Biochemical Testing
151
In specimen collection, explain the **rule of thumb**.
The site of infection is the site of collection
152
_______ are ideal sample for cutaneous infections such as skin or wound infection.
Aspirates
153
If the wound or lesion of the patient did not have fluid/pus, how will you get the sample?
Through a swab
154
_________ are less satisfactory for both culture and smear results.
Swabs
155
In performing a swab collection, what is the important thing to do?
To get from the periphery area where metabolically active bacteria are found.
156
**TRUE or FALSE.**
In performing a swab, you should get from the middle portion of the wound/lesion.
False (periphery)
157
How many swabs should be obtained when collecting a sample?
2 (for culture and smear)
158
What can you expect to see when performing direct microscopic examination with a staphylococci?
Gram positive cocci with polymorphonuclear cells
159
**TRUE OR FALSE.**
If there is no bacteria seen under the microscope during direct microscopic examination, but there is a presence of PMNs, proceed to culture.
True
| Whether you see or did not see bacteria, ALWAYS proceed to culture.
160
What is the purpose of culture?
To propagate the growth of bacteria in order to easily observe its characteristics.
161
What are the typical media used for staphylococci?
- Blood Agar Plate (BAP)
- Chocolate Agar Plate (CAP)
- Mannitol Salt Agar (MSA)
- Columbia Colistin-Nalidixic Acid (CNA)
- Phenylethyl Alcohol Agar (PEA)
- CHROMagar
162
What is the standard incubation period and temperature?
35-37 C for 18-24 hours
163
Describe the colonies of *S. aureus* on BAP during macroscopic examination.
Round, smooth, white, creamy colonies, exhibiting a β-hemolytic pattern
164
Describe the colonies of *S. epidermidis* on BAP during macroscopic examination.
Small to medium-sized, non-hemolytic, gray-to-white colonies
165
Aside from *S. aureus*, which bacterium also exhibits a halophilic characteristic, and is a mannitol fermenter?
*Staphylococcus saprophyticus*
166
_________ uses chromogen to grow bacteria that exhibits a specific color.
Chromogenic Media or Agar
167
_________ exhibits a mauve color.
CHROMagar
168
_________ exhibits a blue-green color.
HiChrome agar
169
A bacteria, exhibiting a gram positive cocci morphology, is seen under the microscope. Which test should be conducted first?
Catalase Test
170
_________ mediates the breakdown of hydrogen peroxide (H2O2) into oxygen and water.
Catalase
171
What is the **positive result** for Catalase Test?
Bubble formation (effervescence)
172
Bubble formation is also known as _________.
Effervescence
173
What is the **negative result** for Catalase Test?
No bubble formation
174
Which bacteria tests negative for Catalase?
- *Streptococcus* spp.
- *Enterococcus* spp.
175
Explain the principle of Catalase Test
**Principle:** Catalase mediates the breakdown of 30% or 3% H2O2 into oxygen and water.
**Result:** (+) bubble formation
176
Which test should be done if we want to identify the presence of *Micrococcus* spp.?
Microdase Test (Modified Oxidase)
177
What is the **positive result** for Microdase Test?
Development of blue to purple-blue color
178
Explain the principle of Microdase Test.
**Principle:** Oxidase enzyme reacts with oxidase reagent and cytochrome C to form a purple-blue indophenol ring after 2 minutes.
**Result:** (+) blue to purple-blue color
179
# Microdase Test
Oxidase enzyme reacts with _________ and ___________.
oxidase reagent and cytochrome C
180
# Microdase Test
The reaction of oxidase enzyme with oxidase reagent and cytochrome C produces ___________.
A blue to purple-blue colored indophenol compound
181
# Microdase Test
When does the Microdase Test exhbit color change?
After 2 minutes
182
___________ is used to determine the effect of bacitracin on an organism.
Bacitracin Test
183
Explain the principle of Bacitracin Test
**Principle:** To determine the effect of 0.04 U of bacitracin on a bacterium.
**Method:** disk diffusion
**Result:** >10 mm zone of inhibition
184
How many bacitracin is utilized for bacitracin test?
0.04 U
185
Which method is used for bacitracin test?
Disk Diffusion
186
What is the **positive result** for Bacitracin Test?
Presence of >10 mm zone of inhibition around the disk
187
What is the **negative result** for Bacitracin Test?
Presence of <10 mm zone of inhibition around the disk or NO ZONE OF INHIBITION at all
188
# **Bacitracin Test**
You noticed a presence of a zone of inhibition around the bacterial disk, with a diameter of 8 mm. What should be the concluded result?
**Negative**
**Reason:** For it to be considered positive, it should have a diameter of 10 mm or more than 10 mm.
189
____________ is used to determine whether an organism uses carbohydrates to produce acid byproducts.
Oxidation-Fermentation (O/F) Reactions
190
Which medium is used in O/F reactions?
Oxidation-Fermentation Basal Medium (OFBM)
191
Which carbohydrates can be used in O/F reactions?
Glucose, xylose, mannitol, lactose, sucrose, and maltose
192
What is the pH indicator in O/F reactions?
Bromothymol blue
193
# Oxidation-Fermentation Reactions (O/F)
What color is the pH indicator if it produces acid?
Yellow
194
# Oxidation-Fermentation Reactions (O/F)
What color is the pH indicator if it did not produce acid?
Green
195
# Oxidation-Fermentation Reactions (O/F)
What color is the pH indicator if it produces an alkaline product?
Blue
196
How do we interpret the result in O/F reactions?
By writing the result of Oxidation first before Fermentation
197
# **Oxidation-Fermentation Reactions (O/F)**
A bacteria exhibited a **+/+** reaction. Which organism is it, and what is its aerotolerance?
**Organism:** *Staphylococcus* spp.
**Aerotolerance:** Facultative Anaerobe
198
# **Oxidation-Fermentation Reactions (O/F)**
A bacteria exhibited a **+/-** reaction. Which organism is it, and what is its aerotolerance?
**Organism:** *Micrococcus* spp.
**Aerotolerance:** Obligate Aerobe
199
# **Oxidation-Fermentation Reactions (O/F)**
A bacteria exhibited a **-/-** reaction. Which organism is it?
**Organism:** Asaccharolytic bacteria such as *Moraxella* spp. and *Alcaligenes* spp.
200
# **Oxidation-Fermentation Reactions (O/F)**
A bacteria exhibited a **-/+** reaction. What is its aerotolerance?
**Aerotolerance:** Obligate Anaerobe
201
Explain the process of O/F reactions
1. We have a culture, and we will transfer the same colonies in two different OFBM medium.
2. **First Tube:** A and **Second Tube:** B.
3. The **first tube** contains **sterile mineral oil** or **melted petrolatum** or **sterile paraffin oil**. This is to promote the anaerobic environment.
4. The **second tube** does **not contain sterile mineral oil** to promote an aerobic environment.
5. Incubate for 18-24 hours at 37°C.
202
_________ is used to differentiate *Staphylococcus aureus* from CoNS by detecting enzyme coagulase.
Coagulase Test
203
What are the two coagulase enzymes?
- Free Coagulase (staphylocoagulase)
- Bound Coagulase (clumping factor)
204
What is the **positive result** for Coagulase Test?
Formation of Clot
205
Which bacteria tests positive for **Slide Coagulase Test**?
- *Staphylococcus aureus*
- *Staphylococcus schleiferi*
- *Staphylococcus lugdunensis*
206
Which bacteria tests negative for Coagulase Test?
5-15% of CoNS
207
___________ are bound to the cell wall and reacts directly with fibrinogen in plasma.
Bound Coagulase or Clumping Factor
208
Bound Coagulase is also known as _________.
Clumping Factor
209
Bound coagulase are bound to the _______ and reacts directly with _______ in plasma.
- cell wall
- fibrinogen
210
The alteration of fibrinogen results to __________.
Precipitation of the staphylococcal cell wall
211
The alteration of _________ results to the precipitation of the staphylococcal cell wall.
Fibrinogen
212
If the cell wall precipitates, what will happen next?
Clumping of cells
213
What is the **positive result** in bound coagulase test?
Clot with clump cells
214
Bound Coagulase Test is performed via _________.
Slide Coagulase Test
215
Slide Coagulase Test is a __________.
Screening Test
216
What reagent is used in performing bound coagulase test?
Human, **Rabbit**, and Pig plasma in EDTA
217
Which reagent is ideal in performing the bound coagulase test?
Rabbit plasma in EDTA
218
If the result turns out to be negative for Bound Coagulase Test, which test should be conducted next?
Free Coagulase Test
219
Explain the principle of Bound Coagulase Test
**Principle:** Bound to the bacterial cell wall and reacts directly with fibrinogen in plasma.
* Alteration of fibrinogen → precipitates on the staphylococcal cell wall (magdidikit yung cells)
**Result:** Clot (clumping of cells)
**Performed in:** Slide Coagulase Test (screening test)
**Reagent:** human, rabbit (ideal) or pig plasma in EDTA
If negative, proceed to free coagulase test.
220
When the extracellular protein enzyme called ________ interacts with _______, it forms a ___________.
Free Coagulase + Coagulase Reacting Factor (CRF) = Coagulase-CRF Complex
221
Coagulase-CRF Complex + __________ = fibrin
Fibrinogen
222
Coagulase-CRF Complex + Fibrinogen = __________
Fibrin
223
What is the **positive result** in free coagulase test?
Fibrin Clot
224
Free Coagulase Test is performed via _________.
Tube Coagulase Test
225
What reagent is used in performing free coagulase test?
Human, **Rabbit** (0.5 mL), and Pig plasma in EDTA incubate at 37 C for 4 hours with monitoring every 30 minutes
226
Why should we monitor the specimen every 30 minutes in free coagulase test?
Because it is capable of autolysis due to the autolytic enzyme Fibrinolysin
227
Which autolytic enzyme is present in free coagulase test?
Fibrinolysin
228
After incubating the specimen processed via free coagulase test for 4 hours with monitoring every 30 minutes, you noticed the absence of clot formation. What should you do next?
Extend incubation at 21-25 C (room temperature) overnight
229
# **Free Coagulase Test**
Why do we extend incubation at 21-25 C and not 37 C when clot formation is absent?
Because the temperature 37 C enhances the autolytic activity of the specimen
230
What enzyme converts fibrinogen to fibrin in humans?
Thrombin
231
Explain the principle of Free Coagulase Test
**Principle:** Extracellular protein enzyme (free coagulase) + CRF (coagulase-reacting factor)
* Coagulase-CRF complex + fibrinogen = fibrin
**Result:** Fibrin clot (possibility of autolysis
due to fibrinolysin)
**Performed in:** Tube Coagulase Test
**Reagent:** human, rabbit (ideal) or pig plasma in EDTA (0.5 mL) incubate at 37°C for 4 hours with monitoring of clot
formation every 30 minutes.
* If there is no clot within 4 hours, extend incubation at 21-25°C overnight.
232
It is done to differentiate *Staphylococcus aureus* from other CoNS by the presence of the enzyme L-pyrroglutamylaminopeptidase.
Pyrrolidonyl Arylamidase (PYR) Test
233
Pyrrolidonyl Arylamidase (PYR) Test is done to differentiate *Staphylococcus aureus* from other CoNS by the presence of the enzyme ______________.
L-pyrroglutamylaminopeptidase
234
L-pyrroglutamylaminopeptidase __________ L-pyrrolidonyl-β-naphthylamide to produce β-naphthylamine
hydrolyzes
235
Which substrate is hyrolyzed by L-pyrroglutamylaminopeptidase to produce β-naphthylamine?
L-pyrrolidonyl- β-naphthylamide
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β-naphthylamine reacts with ____________ to produce a color change (reagent).
N,N-methylaminocinnamaldehyde or P-dimethylaminocinnamaldehyde
237
What is the **positive result** in pyrrolidonyl arylamidase test?
Bright red color
238
Which bacteria exhibit a **positive reaction** with the pyrrolidonyl arylamidase test?
- *S. schleiferi*
- *S. intermedius*
- *S. lugdunensis*
239
What is the **negative result** in pyrrolidonyl arylamidase test?
No color change or orange color
240
Which bacteria exhibit a **negative reaction** with the pyrrolidonyl arylamidase test?
*S. aureus*
241
Explain the principle of Pyrrolidonyl Arylamidase Test
**Principle:** to differentiate *S. aureus* from other CoNS by the presence of the enzyme L-pyrroglutamylaminopeptidase.
* Lpyrroglutamylaminopeptidase (hydrolyzes) → L-pyrrolidonyl-β-naphthylamide/PYR (substrate) = β-naphthylamine
* β-naphthylamine + N, N-methylaminocinnamaldehyde/p-dimethylaminocinnamaldehyde (reagent)
**Result:**
* (+) Bright red color *S. lugdunensis, S. intermedius, S. schleiferi*
* (-) No color change or an orange color *S. aureus*
242
It is used to determine the ability of some organisms to produce neutral end products from glucose fermentation.
Vogue-Proskauer (VP) Test
243
What are examples of neutral end products?
Acetyl-methylcarbinol and acetoin
244
What is the **positive result** in vogue-proskauer test?
Red Color
245
Which bacteria exhibit a **positive reaction** with the vogue-proskauer test?
*S. aureus*
246
What is the **negative result** in vogue-proskauer test?
Yellow Color
247
Which bacteria exhibit a **negative reaction** with the vogue-proskauer test?
- *S. schleiferi*
- *S. intermedius*
- *S. lugdunensis*
- *S. haemolyticus*
248
Explain the principle of Vogue-Proskauer Test
**Principle:** to determine the ability of some organisms to produce neutral end products (acetyl-methylcarbinol or acetoin) from glucose fermentation.
**Result:**
* (+) Red color
* (-) Yellow color
249
It is used to determine the ability of an organism to hydrolyze DNA based on the production of deoxyribonuclease.
DNA Hydrolysis Test
250
Why is the medium in DNA hydrolysis pale green?
Because of the DNA-methyl green complex
251
The ______ will hydrolyze the DNA which causes the pH to drop and for the methyl green to become colorless.
DNAse
252
The DNAse will hydrolyze the DNA which causes the ____ to drop and for the methyl green to become colorless.
pH
253
The DNAse will hydrolyze the DNA which causes the pH to drop and for the methyl green to become _______.
colorless
254
What is the **positive result** in DNA hydrolysis test?
Colorless/Clear
255
Which bacteria exhibit a **positive reaction** with the DNA hydrolysis test?
**MNEMONIC:** SSS Mo
- ***S**taphylococcus aureus*
- ***S**treptococcus pyogenes*
- ***S**erratia* spp.
- ***Mo**raxella* spp.
256
What is the **negative result** in DNA hydrolysis test?
Green Color
257
Explain the principle of DNA Hydrolysis Test
**Principle:** to determine the ability of an organism to hydrolyze DNA based on the production of deoxyribonuclease.
* Medium is pale green because of the DNA-methyl green complex.
* The DNAse will hydrolyze the DNA which causes the pH to drop and for methyl green to be colorless.
**Result:**
* +) Clear
* (-) Green
**Organisms with DNAse:** SSS Mo
* ***S**taphylococcus aureus*
* ***S**treptococcus pyogenes*
* ***S**erratia* spp.
* ***Mo**raxella* spp.
258
It is used to determine the effect of a 5-ug novobiocin disk on an organism (to differentiate CoNS)
Novobiocin Susceptibility Test
259
What is the **positive result** in novobiocin susceptibility test?
Presence of zone of inhibition around the disk with a diameter of 16 mm or >16 mm (susceptible)
260
Which bacteria exhibit a **positive reaction** *(susceptible)* with the novobiocin susceptibility test?
- ***S. epidermidis***
- *S. capitis*
- *S. haemolyticus*
- *S. hominis* subsp. *hominis*
- *S. lugdunensis*
- *S. saccharolyticus*
- *S. warneri*
261
What is the **negative result** in novobiocin susceptibility test?
No presence of zone of inhibition around the disk or presence of <16 mm zone of inhibition
262
Which bacteria exhibit a **negative reaction** *(resistant)* with the novobiocin susceptibility test?
- *S. cohnii*
- *S. kloosii*
- ***S. saprophyticus***
- *S. xylosus*
263
Which group of antibiotics does Penicillin belongs?
Methicillin
264
Penicillin belongs to the group of antibiotics called _______.
Methicillin
265
MRSA stands for _________.
Methicillin-Resistant *Staphylococcus aureus*
266
Penicillinase resistant penicillin
- Nafcillin
- Oxacillin
- Cefoxitin
267
Inducers of mecA resistance
Oxacillin and Cefoxitin (better)
268
MRSE stands for _________.
Methicillin-Resistant *Staphylococcus epidermidis*
269
What is the treatment for MRSE?
Vancomycin
270
VISA
Vancomycin-intermediate *Staphylococcus aureus*
271
VRSA
Vancomycin-resistant *Staphylococcus aureus*
272
It dictates the bacteria to develop resistance against methicillin.
mecA gene
273
Clindamycin belongs to the group of antibiotics called ________.
Macrolide
274
______ belongs to the group of antibiotics called Macrolide.
Clindamycin
275
It dictates the bacteria to develop resistance against macrolide.
erm gene
276
*Alloiococcus otitidis* belongs to the family _________.
Carnobacteriaceae
277
*Staphylococcus capitis* location
Head
278
*Staphylococcus auricularis* location
Ear
279
Low concentration of TSST-1 can lead to ___________.
leakage of endothelial cells
280
High concentration of TSST-1 can lead to __________.
cytotoxicity to the endothelial cells
281
TSST-1 is absorbed through the __________.
vaginal mucosa
282
It is a superantigen which stimulates T-cell proliferation and production of cytokines that leads to the manifestation of symptoms.
Toxic Shock Syndrome Toxin-1 (TSST-1)
283
TSST-1 is a superantigen which stimulates ________ and production of ________ that leads to the manifestation of symptoms.
T-cell proliferation, cytokines
284
A chromosomal mediated toxin
Toxic Shock Syndrome Toxin-1 (TSST-1)
285
It is a bullous exfoliative dermatitis affecting newborns, and previously healthy young children.
Scalded Skin Syndrome
286
A heat-labile sphingomyelinase which catalyzes the hydrolysis of membrane phospholipid resulting in cell lysis.
β-hemolysin
287
It lyses RBCs, and cause severe tissue damage.
α-hemolysin
288
It decreases the ability for clearance of the organism from the site of infection.
Protein A
289
Mannitol Salt Agar (MSA) is selective because of _______.
Its NaCl content (7.5% or 10%)
290
What is the differentiating agent for MSA?
Mannitol + pH indicator
291
pH indicator for MSA
Phenol red
292
The color ______ indicates that an acid is formed in MSA.
Yellow
293
The color ______ indicates that there is no acid formed in MSA.
Red/Pink
294
Phenylethyl Alcohol Agar (PEA) is a ________ medium.
selective
295
What is the inhibitor in PEA?
Phenylethyl alcohol
| Inhibits Gram (-) species
296
Staphylocoagulase producing staphylococci
- *S. aureus*
- *S. intermedius*
- *S. delphini*
- *S. lutrae*
- *S. hyicus* (some)
297
It is known to be an animal pathogen.
*S. intermedius*
298
Which organism is **positive or susceptible** for Bacitracin Test?
*Micrococcus* spp.
299
Which organism is **negative or resistant** for Bacitracin Test?
*S. aureus*
