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45 Cards in this Set
- Front
- Back
what kind of bacteria are staph
gram? anaerobe? mannose fermenting? |
Gram + cocci with grape like clusters
facultative anaerobe ferments mannose (only s.aureus) catalase positive |
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two major causes of hospital-related bacteremias in the U.S.
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Staph aureus and staph epidermidis
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up to 60% of staph organisms may be resistant to what drug
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methicillin (Vancomysin may be drug of last resort)
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Staph: gram? shape?
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gram positive cocci in grape like clusters
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coagulase is a useful distinguishing feature in what kind of staph infections. what is is
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an enzyme that clots human or rabbit plasma by activating fibrinogen. distinguishes Staph aureaus
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Staph. aureus? catalase? ferments manitol?
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catalase positive (strep is catalase neg) and facultative anaerobes
ferments mannitol |
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colonization by staph of the nasal passages is 30-40% higher in what two catagories of patients
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drug users and diabetics
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toxic shock syndrome is caused by what toxin
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toxic shock syndrome toxin by Staph. aureus
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staphylococcal scalded skin syndrome is caused by what toxin
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exfoliatins by staph. aureus
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S. aureus's surface adhesive molecules bind what in host
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host's ECM (fibrinogen, collagen, etc) such proteins are often found on damaged "skin" (catheter site), disrupted airways, or endothelial cells in blood stream
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s. aureus' alpha toxin does what
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lyse host cell membrane
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s. aureus leukocidins does what
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lysis of leukocytes
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s. aureus prtoeases does what
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breakdown host proteins
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s. aureus coagulase does what
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forms clot in human plasma
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s. aureus' staphylokinase does what
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lysis of blood clot or fibronolysis
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s. aureus' hyaluronidase does what
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dissolves hyaluronic acid - a component of the host's cellular matrix
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s. aureus' lipase does what
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dissolves lipids and lipoproteins
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a cell wall protein that binds to host IgG via the Fc receptors, leading to "blinding on the wrong end", less complement-mediated killing. it is a B cell super Ag, leading to defective production of specific IgM
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Protein A secreted by S. aureus. it helps organism evade host immune system
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T cell super antigens which blunts T cell response and is secreted by S. aureus
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enterotoxins A-E, G, H, and I
stimulate IL1, IL2, TNF |
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the capsular polysaccharides on Staph. aureus play a role in what part of pathogenesis
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anti-phagocytic
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a surface protein that impairs neutrophil recruitment and is secreted by s. aureus
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Eap (MAP)
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what happens if a s.aureus infection is not contained the host immune system what might happen
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invasion in to the bloodstream - blood borne infection would ensue - any organ is at risk
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the enterotoxin secreted by s.aureus: heat labile?
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heat stabile - resists boiling
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many enterotoxins secreted by s.aureus are super antigens which stimulate large amounts of of what 3 cytokines
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Il-1 IL-2 and TNF
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what are the clinical syndromes in toxin-mediated s. aureus food poisoning case
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nausea, vomiting, non-bloody diarrhea (all explained by the T cell super antigen effect)
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what toxin causes fever, rash, followed by desquamination of palms, soles, some may have hypotension and shock
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Toxic shock syndrome (TSS), caused by s. aureus is characterized
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Staphylococcal scalded is secreated by specific groups of s.aureus (phage group II) and is characterized histologically by
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superficial layer of epidermis detaching from underlying dermis in response to toxin
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invasive diseases caused by s.aureus are characterized by
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suppuration and abscess formation
e.g catheter site infections |
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nasal colonization by s.aureus can be prevented by
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intranasal mupirocin
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why do you treat s.aureus with semi-synthetic penicillin instead of regular penicillin
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because staph synthesizes penicillinase which renders them resistant to regular penicillin but not synthesized penicillin (e.g dicloxacillin, and oxacillin)
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Staph species which is coagulase negative and sensitive to novobiocin, does not ferment mannitol, and causes very little hemolysis on blood agar
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staph epidermidis
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normal flora of skin and is opportunistic pathogen (especially adheres to foreign bodies)
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S. epidermidis
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surface carbohydrate components on s.epidermidis mediates intercellular adherence or clustering of bacteria - which is called
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biofilm
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what is the treatment for S. epidermis
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Vancomycin
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In a tough case of s. epidermis (perhaps where bacteremia has occured) you might want to consider add what two antibiotics to your treatment with Vancomycin
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rifampin and gentimycin
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Staph species which is coagulase minus and catalase positive, and is RESISTANT to novobiocin
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staph. saprophyticus
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this staph species is a skin commensal and is a comomon cause of UTIs in young women (second to E.coli in this age group)
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s. saprophyticus
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urinary tract infection, polyuria and dysuria would be caused by
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staph. saprophyticus
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what two types of antibiotics would you use to treat s. saprophyticus
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a trimethoprim (Bactrim), and quinolone (norfloxacin) - anything that will penetrate into the urinary bladder
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color of S. aureus, s.epidermis, and s.saprophyticus colonies
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s. aureus is yellow - the other two are white
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which staph species ferment mannitol
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only s. aureus
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whis staph species has DNase, hemolysis
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only s. aureus
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phage recetpro is useful for typing what kind of staph
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s. aureus
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staph aureas metabolic characteristics
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faculatative anaerobe
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how do staph and strep compare in terms of catalase
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staph is catalase positive and strep is catalase negative
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