Staphylococcus Flashcards
Staphylococcus spp. belong to the family ___________.
Staphylococcaceae
Staphylococcus spp. is combined with the _________, __________, and _________ into the order Bacillales.
Bacillaceae, Planococcaceae, and Listeriaceae
Staphylococcus spp. has now been combined with the Bacillaceae, Planococcaceae, and Listeriaceae into the order _________.
Bacillales or Bacillacea
In terms of biochemical examination, majority of the Staphylococcus spp. are __________.
Catalase Positive
Staphylococcus spp. can also be ________, but some can be __________.
Coagulase Positive, some are Coagulase Negative
What do we call the Staphylococcus spp. that are COAGULASE NEGATIVE?
CoNS - Coagulase Negative Staphylococcus
Describe the appearance of Staphylococcus spp.
Gram Positive cocci in singly, in pairs, and in GRAPE-LIKE clusters
Staphylococcus spp. are commonly known for their _________ appearance.
Grape-like
Which bacteria are often mistaken for Staphylococcus?
MNEMONIC: ARA
- Aerococcus spp.
- Rothia mucillaginosa
- Alloiococcus otitidis
Why is ARA mistaken for staphylococcus?
Because they are all Gram Positive cocci
staphylococcus is a _______ of the human skin and mucous membrane.
Normal Flora
staphylococcus is a normal flora of the ________.
Human Skin and Mucous Membrane
Aside from staphylococcus, what are other GRAM POSITIVE normal flora?
- Micrococcus spp.
- Kytococcus spp.
- Kocuria spp.
Staphylococcaceae resembles the family ___________.
Micrococcaceae
Microccocaceae are _________ and __________.
Catalase Positive and Coagulase Negative
Describe the appearance of Micrococcus spp.
Gram Positive cocci in pairs, TETRADS and in irregular clusters.
Describe pigment of the colonies of Micrococcus spp.
Yellow Pigment
Alloiococcus otitidis is recovered from _________.
Human middle ear fluid
How many species are there within the genus Staphylococcus?
39
How many subspecies are there within the genus Staphylococcus?
21
What is the result of the Modified Oxidase (Microdase) Test in micrococci?
Positive (+)
What is the result of the Modified Oxidase (Microdase) Test in staphylococci?
Negative (-)
Anaerobic Acid Production is also called ________.
Fermentation
What is the result of the Anaerobic Acid Production from glucose (fermentation) in staphylococci?
Positive (+)
___________ are fermenters.
staphylococci
What is the result of the Anaerobic Acid Production from glucose (fermentation) in micrococci?
Negative (-)
__________ are oxidizers.
micrococci
What is the aerotolerance of stapylococci?
Facultative Anaerobes
What is the aerotolerance of micrococci?
Obligate Aerobes
What is the result of the Anaerobic Acid Production from glycerol in the presence of erythromycin (fermentation) in staphylococci?
Positive (+)
What is the result of the Anaerobic Acid Production from glycerol in the presence of erythromycin (fermentation) in micrococci?
Negative (-)
Furoxone-Tween 80 oil-red O agar is an example of __________.
Selective Media
Which is the inhibitor in the Furoxone-Tween 80 oil-red O agar?
Furoxone
What is the result of the growth on Furoxone-Tween 80 oil-red O agar in staphylococci?
Negative (-) as it is inhibited by Furoxone
What is the result of the growth on Furoxone-Tween 80 oil-red O agar in micrococci?
Positive (+)
It means that the bacterium is not inhibited by the antibiotic.
Resistant
It means that the bacterium is inhibited by the antibiotic.
Susceptible/Sensitive
Resistance to bacitracin (0.04 U) of staphylococci
Resistant (not inhibited by bacitracin)
Resistance to bacitracin (0.04 U) of micrococci
Susceptible (inhibited by bacitracin)
Resistance to lysosome (50-mg disk) of staphylococci
Resistant (not inhibited by lysosome)
Resistance to lysosome (50-mg disk) of micrococci
Susceptible (inhibited by lysosome)
Resistance to lysostaphin (200 ug/mL) of staphylococci
Susceptible (inhibited by lysostaphin)
Resistance to lysostaphin (200 ug/mL) of micrococci
Resistant (not inhibited by lysostaphin)
All micrococci are OBLIGATE AEROBES except _________.
MNEMONIC: KRIVA
- Micrococcus kristinae
- Micrococcus varians
Micrococcus kristinae and Micrococcus varians are both _________.
Facultative Anaerobes (fermenters)
All staphylococci are NEGATIVE in the MICRODASE TEST except _________.
MNEMONIC: SCLEVI CASE
- Staphylococcus sciuri
- Staphylococcus lentus
- Staphylococcus vitulus
- Macrococcus caseolyticus
Enumerate examples of staphylococci that are positive in the Microdase Test.
MNEMONIC: SCLEVI CASE
- Staphylococcus sciuri
- Staphylococcus lentus
- Staphylococcus vitulus
- Macrococcus caseolyticus
rothia result in Catalase Test
+/-
aerococcus result in Catalase Test
-
enterococcus result in Catalase Test
-
rothia result in Microdase Test
-
aerococcus result in Microdase Test
-
enterococcus result in Microdase Test
-
Aerotolerance of rothia
Facultative Anaerobe
Aerotolerance of aerococcus
Facultative Anaerobe
Aerotolerance of enterococcus
Facultative Anaerobe
Resistance to bacitracin (0.04 U) of rothia
Resistant or Susceptible
Resistance to bacitracin (0.04 U) of aerococcus
Susceptible
Resistance to bacitracin (0.04 U) of enterococcus
Resistant
Resistance to furazolidone (100 ug) of staphylococci
Susceptible
Resistance to furazolidone (100 ug) of micrococci
Resistant
Resistance to furazolidone (100 ug) of rothia
Resistant or Susceptible
Resistance to furazolidone (100 ug) of aerococcus
Susceptible
Resistance to furazolidone (100 ug) of enterococcus
Susceptible
Resistance to lysostaphin (200 ug/mL) of rothia
Resistant
Resistance to lysostaphin (200 ug/mL) of aerococcus
Resistant
Resistance to lysostaphin (200 ug/mL) of enterococcus
Resistant
Staphylococcaceae came from the Greek word ______.
Staphle
Staphle means _________.
Bunches of Grapes
TRUE OR FALSE.
staphylococci are motile
False
TRUE OR FALSE.
staphylococci are non-spore forming
True
TRUE OR FALSE.
Staphylococcus spp. are aerobic
True (some)
Which strains of staphylococci are obligate anaerobes, and catalase negative?
- Staphylococcus saccharolyticus
- Staphylococcus aureus subsp. anaerobius
What is the standard size of staphylococci?
Medium (4 to 8 mm)
Describe the color of staphylococci colonies
Cream-colored (common), white or rarely light gold (golden yellow)
Describe the texture of staphylococci colonies
Buttery-looking
TRUE OR FALSE.
Generally, staphylococci are fastidious.
False
Fastidious staphylococci requirements:
CO2, hemin, menadione, with at least 48 hours of incubation
These are organisms which are capable of developing a polysaccharide that appears as a slime layer.
- Staphylococcus aureus
- Staphylococcus epidermidis
The polysaccharide layer of S. aureus and S. epidermidis allows them to form a _______.
Biofilm
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.
Enumerate the sites where Staphylococcus aureus is found.
- Anterior nares
- Nasopharynx
- Perineal area
- Skin
- Colonizer of mucosa
Boil or Pigsa is medically known as _________.
Furuncle
A cutaneous infection caused by S. aureus which has systemic manifestations.
Carbuncle
A cutaneous infection caused by S. aureus which is characterized by a large pustule with erythema.
Bullous Impetigo
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)
Enumerate the infections caused by Staphylococcus epidermidis.
Nosocomial Infections
Enumerate the sites where Staphylococcus haemolyticus is found.
- Skin
- Mucous membranes
Enumerate the infections caused by Staphylococcus haemolyticus.
- Wound
- Septicemia
- UTIs
- Native Valve Infections
Enumerate the infections caused by Staphylococcus lugdunensis.
- Catheter-related bacteremia
- Endocarditis
Enumerate the infections caused by Staphylococcus saprophyticus.
UTI (in adolescent girls and young women)
Enumerate the sites where Staphylococcus saprophyticus is found.
- Skin
- Genitourinary tract
- Mucosa
Enumerate the sites where Micrococcus spp.,Kytococcus spp., and Kocuria spp. are found.
- Skin
- Mucosa
- Oropharynx
Enterotoxins are serologically grouped into groups _________.
A-E and G-J
What are the three infections associated with Enterotoxins?
- Food Poisoning
- Toxic Shock Syndrome
- Pseudomembranous Enterocolitis
Enterotoxins
Food poisoning is caused by ________.
Enterotoxin Groups A-E
Mahon: A, B, D
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
How can we determine if food poisoning is caused by a virus?
If the incubation period or manifestation of symptoms is longer.
Enterotoxins
Toxic Shock Syndrome is caused by __________.
Enterotoxin Groups B, C, G, I
Enterotoxins
Pseudomembranous enterocolitis is caused by _________.
Enterotoxin Group B
How can you acquire pseudomembranous enterocolitis?
By consuming contaminated milk products
Enterotoxins are stable at __________.
100 C for 30 minutes
How can you get rid of enterotoxins?
By heating them for more than 100 C for more than 30 minutes
A virulence factor of Staphylococcus aureus characterized by desquamation of the skin.
Toxic Shock Syndrome Toxin-1 (TSS)
Toxic Shock Syndrome Toxin-1 (TSS) is previously known as ___________.
Enterotoxin F
Toxic Shock Syndrome Toxin-1 (TSS) is also known as __________.
Pyrogenic Exotoxin C
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.
What happens to the plasma volume when one has hypotension?
Decreases
Who are the people commonly affected by Toxic Shock Syndrome Toxin-1 (TSS)?
Women wearing tampons during menstruation
Exfoliative Toxin is also known as ___________.
Epidermolytic Toxin A & B
Exfoliative toxin is a _________ which splits the intracellular bridges of the epidermis.
Serine protease
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.
Exfoliative toxin causes __________.
Staphylococcal Scalded Skin Syndrome
Staphylococcal Scalded Skin Syndrome is also known as ________.
Ritter Disease
Exfoliative toxin is the causative agent or virulence factor associated with _________.
Bullous Impetigo
___________ is the causative agent or virulence factor associated with bullous impetigo.
Exfoliative Toxin
These are extracellular proteins that affect the RBCs and WBCs.
Cytolytic Toxin or Cytotoxin
_________ targets the red blood cells (RBCs).
Hemolysin
_________ targets the white blood cells (WBCS).
Leukocidins
Hemolysins for Staphylococcus aureus
Alpha, Beta, Gamma, and Delta
It is characterized by the disruption of smooth muscle in the blood vessels, and its toxicity to erythrocytes, leukocytes, hepatocytes, and platelets.
α-hemolysin
α-hemolysin is toxic to ________.
- Erythrocytes
- Leukocytes
- Hepatocytes
- Platelets
It acts on sphingomyelin in the plasma membrane of the RBCs.
β-hemolysin
β-hemolysin is also known as _______.
Sphingomyelinase C or “hot-cold lysin”
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)
It is utilized as a known factor in CAMP test.
β-hemolysin
β-hemolysin is utilized as a known factor in _________.
CAMP Test
CAMP test is used for _______.
Identification of Streptococcus agalactiae
CAMP stands for _______.
Christie, Atkins, Munch-Petersen
__________ is less toxic than α-hemolysin or β-hemolysin.
δ-hemolysin
The following bacteria exhibits δ-hemolysin:
- Staphylococcus aureus
- Staphylococcus epidermidis
- Staphylococcus haemolyticus
__________ functions with Panton-Valentine Leucocidin (PVL).
γ-hemolysin
Panton-Valentine Leucocidin (PVL) targets the _________.
Polymorphonuclear Cells (PMN)
It is an exotoxin lethal to polymorphonuclear cells (PMS).
Panton-Valentine Leucocidin (PVL)
What does Panton-Valentine Leucocidin (PVL) do to phagocytes?
Suppress
Panton-Valentine Leucocidin (PVL) is associated with __________.
Severe cutaneous infections and necrotizing pneumonia
Panton-Valentine Leucocidin (PVL) is often associated with __________.
Community-acquired staphylococcal infections
What are the enzymes produced by staphylococci?
Coagulase, Protease, Hyaluronidase, and Lipase
Staphylocoagulase is also known as _________.
Free coagulase
An enzyme produced by staphylococci that is known to be a spreading factor.
Hyaluronidase
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.
Lipase is produced by both ___________.
Coagulase Positive and CoNS
________ acts on lipids present on the surface of the skin.
Lipase
Protein A is found in the _________.
Cell wall
A virulence factor of staphylococci that is found in the cell wall.
Protein A
________ binds to the Fc portion of immunoglobulin G .
Protein A
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
A virulence factor of staphylococci that activates complement, IL-1, chemotactic to PMNs.
Peptidoglycan
A virulence factor of staphylococci that mediates binding to fibronectin.
Teichoic Acid
Enumerate the workflow in performing a laboratory test.
- Specimen Collection
- Direct Microscopic Examination
- Culture
- Macroscopic and Microscopic Examination
- Biochemical Testing
In specimen collection, explain the rule of thumb.
The site of infection is the site of collection
_______ are ideal sample for cutaneous infections such as skin or wound infection.
Aspirates
If the wound or lesion of the patient did not have fluid/pus, how will you get the sample?
Through a swab
_________ are less satisfactory for both culture and smear results.
Swabs
In performing a swab collection, what is the important thing to do?
To get from the periphery area where metabolically active bacteria are found.
TRUE or FALSE.
In performing a swab, you should get from the middle portion of the wound/lesion.
False (periphery)
How many swabs should be obtained when collecting a sample?
2 (for culture and smear)
What can you expect to see when performing direct microscopic examination with a staphylococci?
Gram positive cocci with polymorphonuclear cells
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.
What is the purpose of culture?
To propagate the growth of bacteria in order to easily observe its characteristics.
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
What is the standard incubation period and temperature?
35-37 C for 18-24 hours
Describe the colonies of S. aureus on BAP during macroscopic examination.
Round, smooth, white, creamy colonies, exhibiting a β-hemolytic pattern
Describe the colonies of S. epidermidis on BAP during macroscopic examination.
Small to medium-sized, non-hemolytic, gray-to-white colonies
Aside from S. aureus, which bacterium also exhibits a halophilic characteristic, and is a mannitol fermenter?
Staphylococcus saprophyticus
_________ uses chromogen to grow bacteria that exhibits a specific color.
Chromogenic Media or Agar
_________ exhibits a mauve color.
CHROMagar
_________ exhibits a blue-green color.
HiChrome agar
A bacteria, exhibiting a gram positive cocci morphology, is seen under the microscope. Which test should be conducted first?
Catalase Test
_________ mediates the breakdown of hydrogen peroxide (H2O2) into oxygen and water.
Catalase
What is the positive result for Catalase Test?
Bubble formation (effervescence)
Bubble formation is also known as _________.
Effervescence
What is the negative result for Catalase Test?
No bubble formation
Which bacteria tests negative for Catalase?
- Streptococcus spp.
- Enterococcus spp.
Explain the principle of Catalase Test
Principle: Catalase mediates the breakdown of 30% or 3% H2O2 into oxygen and water.
Result: (+) bubble formation
Which test should be done if we want to identify the presence of Micrococcus spp.?
Microdase Test (Modified Oxidase)
What is the positive result for Microdase Test?
Development of blue to purple-blue color
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
Microdase Test
Oxidase enzyme reacts with _________ and ___________.
oxidase reagent and cytochrome C
Microdase Test
The reaction of oxidase enzyme with oxidase reagent and cytochrome C produces ___________.
A blue to purple-blue colored indophenol compound
Microdase Test
When does the Microdase Test exhbit color change?
After 2 minutes
___________ is used to determine the effect of bacitracin on an organism.
Bacitracin Test
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
How many bacitracin is utilized for bacitracin test?
0.04 U
Which method is used for bacitracin test?
Disk Diffusion
What is the positive result for Bacitracin Test?
Presence of >10 mm zone of inhibition around the disk
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
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.
____________ is used to determine whether an organism uses carbohydrates to produce acid byproducts.
Oxidation-Fermentation (O/F) Reactions
Which medium is used in O/F reactions?
Oxidation-Fermentation Basal Medium (OFBM)
Which carbohydrates can be used in O/F reactions?
Glucose, xylose, mannitol, lactose, sucrose, and maltose
What is the pH indicator in O/F reactions?
Bromothymol blue
Oxidation-Fermentation Reactions (O/F)
What color is the pH indicator if it produces acid?
Yellow
Oxidation-Fermentation Reactions (O/F)
What color is the pH indicator if it did not produce acid?
Green
Oxidation-Fermentation Reactions (O/F)
What color is the pH indicator if it produces an alkaline product?
Blue
How do we interpret the result in O/F reactions?
By writing the result of Oxidation first before Fermentation
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
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
Oxidation-Fermentation Reactions (O/F)
A bacteria exhibited a -/- reaction. Which organism is it?
Organism: Asaccharolytic bacteria such as Moraxella spp. and Alcaligenes spp.
Oxidation-Fermentation Reactions (O/F)
A bacteria exhibited a -/+ reaction. What is its aerotolerance?
Aerotolerance: Obligate Anaerobe
Explain the process of O/F reactions
- We have a culture, and we will transfer the same colonies in two different OFBM medium.
- First Tube: A and Second Tube: B.
- The first tube contains sterile mineral oil or melted petrolatum or sterile paraffin oil. This is to promote the anaerobic environment.
- The second tube does not contain sterile mineral oil to promote an aerobic environment.
- Incubate for 18-24 hours at 37°C.
_________ is used to differentiate Staphylococcus aureus from CoNS by detecting enzyme coagulase.
Coagulase Test
What are the two coagulase enzymes?
- Free Coagulase (staphylocoagulase)
- Bound Coagulase (clumping factor)
What is the positive result for Coagulase Test?
Formation of Clot
Which bacteria tests positive for Slide Coagulase Test?
- Staphylococcus aureus
- Staphylococcus schleiferi
- Staphylococcus lugdunensis
Which bacteria tests negative for Coagulase Test?
5-15% of CoNS
___________ are bound to the cell wall and reacts directly with fibrinogen in plasma.
Bound Coagulase or Clumping Factor
Bound Coagulase is also known as _________.
Clumping Factor
Bound coagulase are bound to the _______ and reacts directly with _______ in plasma.
- cell wall
- fibrinogen
The alteration of fibrinogen results to __________.
Precipitation of the staphylococcal cell wall
The alteration of _________ results to the precipitation of the staphylococcal cell wall.
Fibrinogen
If the cell wall precipitates, what will happen next?
Clumping of cells
What is the positive result in bound coagulase test?
Clot with clump cells
Bound Coagulase Test is performed via _________.
Slide Coagulase Test
Slide Coagulase Test is a __________.
Screening Test
What reagent is used in performing bound coagulase test?
Human, Rabbit, and Pig plasma in EDTA
Which reagent is ideal in performing the bound coagulase test?
Rabbit plasma in EDTA
If the result turns out to be negative for Bound Coagulase Test, which test should be conducted next?
Free Coagulase Test
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.
When the extracellular protein enzyme called ________ interacts with _______, it forms a ___________.
Free Coagulase + Coagulase Reacting Factor (CRF) = Coagulase-CRF Complex
Coagulase-CRF Complex + __________ = fibrin
Fibrinogen
Coagulase-CRF Complex + Fibrinogen = __________
Fibrin
What is the positive result in free coagulase test?
Fibrin Clot
Free Coagulase Test is performed via _________.
Tube Coagulase Test
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
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
Which autolytic enzyme is present in free coagulase test?
Fibrinolysin
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
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
What enzyme converts fibrinogen to fibrin in humans?
Thrombin
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.
It is done to differentiate Staphylococcus aureus from other CoNS by the presence of the enzyme L-pyrroglutamylaminopeptidase.
Pyrrolidonyl Arylamidase (PYR) Test
Pyrrolidonyl Arylamidase (PYR) Test is done to differentiate Staphylococcus aureus from other CoNS by the presence of the enzyme ______________.
L-pyrroglutamylaminopeptidase
L-pyrroglutamylaminopeptidase __________ L-pyrrolidonyl-β-naphthylamide to produce β-naphthylamine
hydrolyzes
Which substrate is hyrolyzed by L-pyrroglutamylaminopeptidase to produce β-naphthylamine?
L-pyrrolidonyl- β-naphthylamide
β-naphthylamine reacts with ____________ to produce a color change (reagent).
N,N-methylaminocinnamaldehyde or P-dimethylaminocinnamaldehyde
What is the positive result in pyrrolidonyl arylamidase test?
Bright red color
Which bacteria exhibit a positive reaction with the pyrrolidonyl arylamidase test?
- S. schleiferi
- S. intermedius
- S. lugdunensis
What is the negative result in pyrrolidonyl arylamidase test?
No color change or orange color
Which bacteria exhibit a negative reaction with the pyrrolidonyl arylamidase test?
S. aureus
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
It is used to determine the ability of some organisms to produce neutral end products from glucose fermentation.
Vogue-Proskauer (VP) Test
What are examples of neutral end products?
Acetyl-methylcarbinol and acetoin
What is the positive result in vogue-proskauer test?
Red Color
Which bacteria exhibit a positive reaction with the vogue-proskauer test?
S. aureus
What is the negative result in vogue-proskauer test?
Yellow Color
Which bacteria exhibit a negative reaction with the vogue-proskauer test?
- S. schleiferi
- S. intermedius
- S. lugdunensis
- S. haemolyticus
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
It is used to determine the ability of an organism to hydrolyze DNA based on the production of deoxyribonuclease.
DNA Hydrolysis Test
Why is the medium in DNA hydrolysis pale green?
Because of the DNA-methyl green complex
The ______ will hydrolyze the DNA which causes the pH to drop and for the methyl green to become colorless.
DNAse
The DNAse will hydrolyze the DNA which causes the ____ to drop and for the methyl green to become colorless.
pH
The DNAse will hydrolyze the DNA which causes the pH to drop and for the methyl green to become _______.
colorless
What is the positive result in DNA hydrolysis test?
Colorless/Clear
Which bacteria exhibit a positive reaction with the DNA hydrolysis test?
MNEMONIC: SSS Mo
- Staphylococcus aureus
- Streptococcus pyogenes
- Serratia spp.
- Moraxella spp.
What is the negative result in DNA hydrolysis test?
Green Color
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
* Staphylococcus aureus
* Streptococcus pyogenes
* Serratia spp.
* Moraxella spp.
It is used to determine the effect of a 5-ug novobiocin disk on an organism (to differentiate CoNS)
Novobiocin Susceptibility Test
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)
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
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
Which bacteria exhibit a negative reaction (resistant) with the novobiocin susceptibility test?
- S. cohnii
- S. kloosii
- S. saprophyticus
- S. xylosus
Which group of antibiotics does Penicillin belongs?
Methicillin
Penicillin belongs to the group of antibiotics called _______.
Methicillin
MRSA stands for _________.
Methicillin-Resistant Staphylococcus aureus
Penicillinase resistant penicillin
- Nafcillin
- Oxacillin
- Cefoxitin
Inducers of mecA resistance
Oxacillin and Cefoxitin (better)
MRSE stands for _________.
Methicillin-Resistant Staphylococcus epidermidis
What is the treatment for MRSE?
Vancomycin
VISA
Vancomycin-intermediate Staphylococcus aureus
VRSA
Vancomycin-resistant Staphylococcus aureus
It dictates the bacteria to develop resistance against methicillin.
mecA gene
Clindamycin belongs to the group of antibiotics called ________.
Macrolide
______ belongs to the group of antibiotics called Macrolide.
Clindamycin
It dictates the bacteria to develop resistance against macrolide.
erm gene
Alloiococcus otitidis belongs to the family _________.
Carnobacteriaceae
Staphylococcus capitis location
Head
Staphylococcus auricularis location
Ear
Low concentration of TSST-1 can lead to ___________.
leakage of endothelial cells
High concentration of TSST-1 can lead to __________.
cytotoxicity to the endothelial cells
TSST-1 is absorbed through the __________.
vaginal mucosa
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)
TSST-1 is a superantigen which stimulates ________ and production of ________ that leads to the manifestation of symptoms.
T-cell proliferation, cytokines
A chromosomal mediated toxin
Toxic Shock Syndrome Toxin-1 (TSST-1)
It is a bullous exfoliative dermatitis affecting newborns, and previously healthy young children.
Scalded Skin Syndrome
A heat-labile sphingomyelinase which catalyzes the hydrolysis of membrane phospholipid resulting in cell lysis.
β-hemolysin
It lyses RBCs, and cause severe tissue damage.
α-hemolysin
It decreases the ability for clearance of the organism from the site of infection.
Protein A
Mannitol Salt Agar (MSA) is selective because of _______.
Its NaCl content (7.5% or 10%)
What is the differentiating agent for MSA?
Mannitol + pH indicator
pH indicator for MSA
Phenol red
The color ______ indicates that an acid is formed in MSA.
Yellow
The color ______ indicates that there is no acid formed in MSA.
Red/Pink
Phenylethyl Alcohol Agar (PEA) is a ________ medium.
selective
What is the inhibitor in PEA?
Phenylethyl alcohol
Inhibits Gram (-) species
Staphylocoagulase producing staphylococci
- S. aureus
- S. intermedius
- S. delphini
- S. lutrae
- S. hyicus (some)
It is known to be an animal pathogen.
S. intermedius
Which organism is positive or susceptible for Bacitracin Test?
Micrococcus spp.
Which organism is negative or resistant for Bacitracin Test?
S. aureus