2.1 Gram Positive, Catalase positive Bac Flashcards
What is the composition of peptidoglycan?
N-acetylglucosamine
N-acetylmuramic acid
Is peptidoglycan a singled or multilayered?
Multilayered
The 2 composition of peptidoglycan is connected by?
Peptide bonds
Gram positive cocci has a thick or thin layer of peptidoglycan?
Thick
Gram-positive infections are?
Pyogenic
How to differentiate gram positive Cocci?
Catalase test
What can be found in catalase positive for Gram positive cocci?
Micrococcaceae
Staphylococcaceae
What can be found in catalase Negative for Gram positive cocci?
Streptococcaceae
What is the characteristics of Staphylococci?
Catalase positive
Clusters
Nonmotile
Non-spore forming
Aerobic or Facultative anaerobes
What is the Gaseous composition for S. saprophyticus
Obligate Anaerobe
Is staphylococcus non capsulated?
Yes
Is staphylococcus Oxidase positive?
False
What environment does staphylococcus grow on?
7.5% NaCl (Salt tolerance test)
What reagent is used in catalase test?
3, 10, 30% hydrogen peroxide (H2O2)
What is the molarity of H2O2 in staphylococcus?
3%
How do we know if we isolated staphylococcus and micrococcaceae
Bubble formation
What organisms can be seen in negative catalase test?
Streptococcus
What are the clinically significant Normal flora species in Staphylococcaceae?
Aureus
Epidermidis
Saprophyticus
Staphylococcus aureus is a normal flora of what part of the body?
Nares
Staphylococcus epidemidis
Skin
Staphylococcus saprophyticus is a normal flora of what part of the body?
Genital tract
Most clinically significant species of Staphylococci
S. aureus
Staphylococcus is usually present in skin surfaces, is it normal?
no
S. aureus usually cause nosocomial infection?
True
What are the virulence factor for S. aureus?
Enterotoxins (A-E & G-J)
Exfoliative Toxin
Cytolytic toxins
Protein A
Beta Lactamase
Is S. aureus an opportunistic pathogens
True
A virulence factor of S. aureus that can survive 100 degrees Celsius for 30 mins which is a heat stable
Enterotoxins
What Enterotoxins of S. aureus are associated with Food poisoning?
A, B, D
Enterotoxin B of S. aureus is associated with what disease?
Pseudomembranous enterocolitis (colitis) / Ulcerative colitis
What does pseudomembranous colitis do in the lining of the intestine?
It produces pus which thickens the lining of the intestines.
A superantigen syndrome that stimulates T-cell proliferation which produce large amount of cytokines.
Toxic shock syndrome toxin-1
What enterotoxin is associated with TSST-1?
Enterotoxin F
TSST-1 can cause mensturating-associated TSS which is usually acquired by?
Unreplaced tampons
This virulence factor causes the skin to slough off which causes the SSS
Exfoliative toxin
Another name for exfoliative toxin
Epidermolytic toxin a and b
What disease or syndrome cause by exfoliative toxin
Scalded skin syndrome (Ritter disease)
Bullous impetigo (Blister-like)
A Cytolytic Toxin that can damage platelets, macrophages and can cause severe tissue damage.
Alpha hemolysin
A Cytolytic Toxin that acts on sphingomyelin in the plasma membrane of erythrocytes which is called “hot and cold” lysin
Beta hemolysin
What disease can be associated with gamma hemolysin?
Panton-Valentine Leukocidin
What is Panton-Valentine Leukocidin?
Elimination of neutrophils and Macrophages
Other name of coagulase in Staphylococci
Staphylocoagulase
Fibrinogen to fibrin
Other name of fibrinolysin in staphylococci?
Staphylokinase
Breaks fibrin
Protease
Cleaves protein
A spreading factor of staphylococcus
Targets patient connective tissue
hyaluronidase
Hydrolyzes lipids
lipase
IT is considered virulence marker of staphylococcus which can differentiate from other Staphylococcus spp.
Staphylocoagulase
Virulence factor of Staphylococcus is the ability to bind the Fc to IgG which blocks Phagocytosis
Protein A
Virulence factor that is responsible for drug resistance factor for Staphylococcus
Beta Lactamase
Patient has High fever and low bp level. In addition, the patient has high DIC. Patient said that he frequently uses tampons. What is the disease or syndrome associated with?
Toxic Shock syndrome Toxin-1
Earliest signs of TSST-1?
Exfoliative toxins
Ritter disease and Bullous Impetigo
What happens if TSST-1 is left untreated?
Multiple organ failure
What will happen if S.aureus penetrate to blood stream?
Endocarditis
Osteomyelitis
Arthritis
Nosocomial infection
What is the virulence factor for S. epidermidis
Exopolysaccharide slide or biofilm
- adheres to medical devices and provides refractoriness to host defense
What are the disease associated with S. epidermidis
Hospital acquired UTI
Prosthetic valve endocarditis (not wearing gloves)
How is hospital acquired UTI occur?
Unreplaced catheter
What is the virulence factor for S. saprophyticus
Adhere to epithelial cell lining in urogenital tract
What are the disease associated with S. saprophyticus
UTI
Common in young females
Sexual activity
A bacteria that can cause both community associated and hospital acquired infection.
It more virulent in prosthetic valve endocarditis than epidermidis
S. lugdunensis
What is the virulence facto of S. Lugdunensis?
Gene mecA
What is gene mecA?
Oxacillin resistant
It has a Vancomycin resistant as a virulence factor
S. Haemolyticus
What are the specimen for Staphylococcaceae
Aspirate
Swabs
Culture media for staphylococcus?
Blood agar
Colistin-Nalidixic acid
Phenylethyl alcohol agar
Mannitol salt agar
CHROM agar
What is the purpose of Blood agar in Staphylococcus
Enriched isolation
What is the purpose of Colistin-Nalidixic in Staphylococcus
Selective medium for gram positive cocci
What is the purpose of Mannitol salt agar in Staphylococcus
Selective and differential
What is the purpose of CHROM in Staphylococcus
Selective and Differential for Methicillin-resistant S. aureus
It test the ability to breakdown Hydrogen peroxide into oxygen and water
Catalase test
Amount of hydrogen peroxide use for Staphylococcaceae
3%
where 30% H2O2 is use for in catalase test
Mycobacterium and Neisseria
What organisms is positive for catalase in gram positive cocci?
Staphylococcus and micrococcus
What organisms is negative for catalase test in gram positive cocci?
Streptococcus
What is the indicator for catalase test if it is positive?
Bubbles
A test for the ability of the bacteria to convert fibrinogen to fibrin
This test can differentiate from aureus to other Staphylococci
Coagulase test
What are the 2 types of coagulase test?
Bound and free
What is the best sample for Staphylococcaceae
Aspirate
A type of coagulase test that uses slide method wherein plasma is put on the slide.
Bound coagulase
A type of coagulase test that uses a tube method
Free coagulase
How many hours to confirm if the free coagulase test is positive?
4-6 hrs
18-24 hrs if the there is no agglutination or clot on the first 4-6 hrs
What is the positive indicator for coagulase test?
Clot or clumping
What organisms is positive in coagulase test? why?
Staphylococcus aureus
Because of the presence of Staphylocoagulase
This test differentiate S. epidermidis and S. saprophyticus
Novobiocin test
It is a clear zone that surrounds the antibiotic which shows it’s effectiveness and the susceptibility of the bacteria to it.
Zone of inhibition (16mm) - novobiocin
How many grams of Novobiocin is used in Novobiocin test?
5ug
What organisms is resistant to Novobiocin?
Staphylococcus saprophyticus
What organisms is susceptible to Novobiocin?
Staphylococcus epidermidis
What is being test for in Microdase test?
Cytochrome C
What differentiates in microdase test?
Staphyloccoci and Micrococcus
What is positive indicator for microdase test?
Blue to purple-blue
What organisms is positive in microdase test?
Micrococcus spp.
A selective and differential agar that uses NaCl
Ability to ferment mannitol
Mannitol salt agar
How many percentage of NaCl in Mannitol salt agar?
7.5%
What is the positive indicator for mannitol salt agar?
Fermentation (Yellow halo around growth)
What organisms is positive in mannitol salt agar?
Staphylococcus aureus
Other name for Bacitracin?
Bacitracin taxo A
What is the purpose of Bacitracin?
Differentiates micrococcus spp. to Staphylococcus spp.
What is the zone of inhibition for bacitracin
10mm
What is the positive organisms for bacitracin?
Micrococcus spp.
It test the ability to hydrolyze DNA
DNAse test
What are the 2 methods for DNase test?
Toluidine blue w/ Methyl green
HCl precipitation
What is the postive indicator for DNAse test?
Clear zone
What organisms is positive for DNAse test
Staphylococcus aureus
What is the principle for DNAse test?
Clearing
Break down DNA making a clearing zone
Test for the ability of the organism to hydrolyze the substrate L-pyrrolidonylβ-napththylamide to l-pyrrolidone and β-naphthylamine,
Pyrrolidonyl aminopeptidase
What is the positive indicator for pyrrolidonyl aminopeptidase?
Bright red after 5mins
What organisms is positive for pyrrolidonyl aminopeptidase?
Staphylococcus epidermidis and saprophyticus
What organisms is negative for pyrrolidonyl aminopeptidase?
Staphylococcus lugdunensis and haemolyticus
It is considered Gold standard for bacteria identification
Real time Polymerase chain Reaction
Next Gold standard considered after RTPCR in identifying bacteria?
Culture
This targets the rRNA sequences for Staphylococcal identification from from blood cultures
Qualitative nucleic acid hybridization assays
This detects turbidity of the bacteria and Continues to be integrated as U.S. Food and Drug Administration (FDA)
approval occur
Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry
Who issued the standard guidelines for antimicrobial susceptibility test
Clinical and Laboratory standards Institute (CLSI)
This encodes penicillin-binding proteins (Oxacillin resistant)
mecA gene
What antimicrobial is use to treat methicillin-resistant Staphylococcus aureus?
Vancomycin and Oxacillin
What is being use to determine methicillin resistance?
Cefoxitin
How cefoxitin confirms MRSA?
NO zone of inhibition (Resistant to Cefoxitin)
What is the drug of choice for MRSA?
Vancomycin
This antimicrobial is frequently use for Staphylococcal skin infections
Can also be use to treat MRSA
Clindamycin
What antimicrobial is use in D-zone test?
Erythromycin and Clindamycin disks
What is the presence of D-shaped for clindamycin say?
Induced clindamycin resistant
Meaning, Clindamycin cannot be use for treatment for staphylococcus infection.
Pseudomembranous ulcerative colitis is associated by what bacteria?
Staphylococcus aureus
Clostridium Difficile