UMMC micro test2 14-15th
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What gram stain are staphylococcus?
Do staphylococcus stay in singles or form clusters?
What aerobic classification are staphylococcus?
Are staphylococcus fermenters?
Do staphylococcus produce catalase?
Does staph aureus have catalase, coagulase, mannitol, and urease?
- Yes on everything but urease
- Coagulase especially defines staph aureus and correlates with virulence
Does staph epidermis have catalase, coagulase, mannitol, and urease?
Yes on catalase, no on the rest
Does staph saprophyticus have catalase, coagulase, mannitol, and urease?
Yes on catalase and urease, no on coagulase and mannitol
Does streptococcus produce catalase?
What form of staphylococcus releases urease?
Explain the difference between Staphylococcus saprophyticus in the Vagina and in the Urinary bladder
- Vagina -> Anaerobic conditions -> Hemagglutinin #1 -> colonization w/o damage
- Urinary bladder -> Aerobic conditions -> Hemagglutinin #2 -> Urease -> infection +Alkaline pH -> tissue damage and kidney stones
Does lysozyme kill staph?
Does Phospholipase A2 kill staph?
- Especially at 33-35degC
What is it called when hair follicles are infected?
What is a boil called?
- These are extremely painful
- Thick pus if caused by staph, thin if strep
What is a Carbuncle?
Multifple skin lesions connected by sinuses in the connective tissue (pack of boils)
What is crusting vesicle formation of the skin?
What is an infection of the nail bed?
What is cellulitis?
A spreading connective tissue infection
What is an eyelid infection?
What is a corneal infection?
What is an inner eye infection?
What mediates the fluid filled eruptions in Bulbus Impetigo?
What is the leading cause of Blepharitis?
What are the three leading agents of microbial keratitis in order?
- Staphylococcus – most common
Once staphylococcus gets into the blood, what are the three places it can travel to?
Once staphylococcus gets into the sinuses where can it travel to?
What is the biggest cause of osteomyelitis?
What are the functions of Protein A on the cell wall and in secreted form?
- Cell wall: binds Fc portion of IgG
- Secreted: Binds TNF-alpha receptor which causes inflammation, this induces protease that removes TNF-alpha receptors
What type proteins are produced in the Staphylococcus during the Log phase?
Predominately Cell Wall Proteins
What type proteins are produced in the Staphylococcus during the stationary phase?
Exoproteins such as secreted toxins
How does the accessory growth regulation system (AGR) regulate bacteria?
- When bacteria concentration is low bacteria builds proteins that are cell wall proteins and inducers.
- When bacteria concentration gets high the inducers start binding to receptors.
- This shuts off cell wall production and begins exotoxin production.
What is the predominate genetic regulator of AGR?
Why can Small Colony Variants survive inside cells?
- They lack cytochrome which stops them from making alpha-toxin
- (A mutant can arise which makes alpha toxin and releases both SCV and toxin-producing cells, leading to recurrent infections)
Why can AGR mutants lead to recurrent infections?
- AGR mutant cannot make exotoxins
- When phagocytized they replicate inside cells
- back mutation allows alpha-toxin production which lyses cells allowing both forms to escape
How does Alpha-Toxin cause bloody pneumonia?
- It causes sloughing off of respiratory epith.
- It kills capillary endothelium
- Blood then leaks
What do modulins do?
- Kill PMNs
- May help bacteria spread from biofilm
How is the toxic shock syndrome gene transferred?
- It is a Pathogenicity island
- Leaves staph during infection with 80 alpha phage
What are two toxic diseases caused by staphylococcus aureus?
- Scalded skin syndrome
- Bulbous Impetigo
Is exfoliative Toxin A found on a chromosome or plasmid?
- toxin B is found on a plasmid
What are Integrated Conjugal Elements (ICE)?
They mediate transfer of large chromosomal regions. They create hybrid or new strains
What drugs are useful in treating CA-MRSA in an outpatient setting?
Sulfa-trimethoprim and rifampin
What does SCCmec code for?
Penicillin Binding Protein 2a
What beta lactam still fits into the Mec A coded transpeptidase? (PBP2a)
Ceftaroline, but it is susceptible to beta lactamase, so must use with a beta lactamase inhibitor
What three factors favor expression of the mecA gene?
- High salt
- Reduced Temperature (~30degC)
- Beta lactam antibiotics
What does the ccr region of the SCCmec cassette code for?
A recombinase that allows the cassette to acquire more DNA
What is VIRSA?
- Intermediate level of resistance to Vancomycin
- Mediated by a thick cell wall that retains d-ala-d-ala
- Plasmid derived from VRE (vancomycin resistant enterococcus)
What does alpha toxin bind to?
Lipid (cholesterol) and Adam 10
What is adam 10?
- Matrix metalloproteinase that becomes active once alpha-toxin binds to it
- It cleaves e-cadherin which holds epithelial and endothelial cells in place
What are the eight main staphylococcus structural virulence factors?
- PIA (for clumps and biofilm)
- Clumping factor
- Fibronectin binding protein
- Protein A
- Collagen binding protein
- Teichoic acid
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