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37 Cards in this Set
- Front
- Back
Gram positive organisms
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Staph, strep, clostridium, corynebacterium, bacillus, listeria, actinomyces, nocardia
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Bugs that do not Gram stain well
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"These Rascals May Microscopically Lack Color"
Treponema Rickettsia Mycobacteria Mycoplasma Legionella Chlamydia |
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Giemsa stain organisms
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Borrelia, Plasmodium, trypanosomes, Chlamydia
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What do you use PAS (periodic acid-Schiff) stains for?
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Stains glycogen, mucopolysaccharides; used to diagnose Whipple's disease (Tropheryma whippelii)
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Ziehl-Neelsen is used in what kind of stain for what organisms?
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Acid-fast stains for organisms like mycobacteria and cryptosporidium
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India Ink stain is used to visualize what organism?
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Cryptococcus neoformans
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Silver stain is used to visualize what organisms?
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Fungi (ie: Pneumocystis), Legionella
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what is enriched media
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Used for H. influenzae. Media enriched with chocolate agar with factors V (NAD+) and X (hematin)
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What is selective media?
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"to connect to Neisseria, please use your VPN client"
Vancomycin (inhibit gram-positive organisms) Polymyxin (inhibits gram-negative organisms) Nystatin (inhibits fungi) |
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What is Bordet-Gengou agar used to grow?
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Bordetella pertussis
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What is Tellurite plate used to grow?
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C. diphtheriae
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What is Loffler's media used to grow?
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C. diphtheriae
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What is Lowenstein-Jensen agar used to grow?
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M. tuberculosis
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What is Eaton's agar used to grow?
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M. pneumoniae
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What is MacConkey's agar used to grow and how to you read it?
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Lactose-fermenting enterics produce acid, turning the plate pink
also an example of "differential media" |
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What is Sabouraud's agar used to grow?
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Fungi
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What is used to grow Legionella?
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Charcoal yeast extract agar buffered with cysteine
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What are the obligate aerobes?
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"Nagging Pests Must Breathe"
Nocardia Pseudomonas Mycobacterium tuberculosis Bacillus |
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What are the obligate anaerobes?
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"anaerobes Can't Breathe Air"
Clostridium Bacteroides Actinomyces lack catalase and/or superoxide dismutase and are thus susceptible to oxidative damage. Generally foul smelling (short-chain fatty acids), difficult to culture, and produce gas in tissue (CO2 and H2) |
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What are obligate intracellular organisms?
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Rickettsia and Chlamydia
Can't make their own ATP |
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What are the facultative intracellular organisms?
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"Some Nasty Bugs May Live FacultativeLy"
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella |
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What are the Urease-positive bugs?
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"Particular Kinds Have Urease"
Proteus, Klebsiella, H. pylori, Ureaplasma |
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What are the pigment-producing bacteria?
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Actinomyces israelii: yellow "sulfur" granules
S. aureus: yellow pigment Pseudomonas aeruginosa: blue-green pigment Serratia marcescens: red pigment |
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What are superantigens?
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Superantigens bind directly to MHC II and T-cell receptor simultaneously, activating large numbers of T cells to stimulate release of INF-gamma and IL-2.
Examples: S. aureus: TSST-1, entertoxins, exfoliatin S. pyogenes: scarlet fever-erythrogenic toxin --> toxic shock like syndrome |
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ADP ribosylating A-B toxins
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Interferes with host cell function. B = binding component, A = attaches an ADP-ribosyl to a host cell protein altering protein function
Examples: C. diphtheriae, V. cholerae, E. coli, B. pertussis |
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Explain the mechanism of action of C. diphtheriae toxin
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Inactivates elongation factor (EF-2) causes pharyngitis and pseudomembrane in throat
similar to pseudomonas exotoxin A |
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Explain the mechanism of action of V. cholerae toxin
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ADP ribosylation of G protein stimulates adenylyl cyclase, increase pumping of Cl into gut and decrease Na absorption. H2O moves into gut lumen; causes voluminous rice-water diarrhea
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Explain the mechanism of action of E. coli toxin
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Heat-labile toxin stimulates Adenylate cyclase. Heat-stable toxin stimulates Guanylate cyclase. Both cause watery diarrhea. "Labile like the Air, stable like the Ground."
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Explain the mechanism of action of Bordetella pertussis toxin
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Increases cAMP by inhibiting Galphai; causes whooping cough; inhibits chemokine receptor, causing lymphocytosis
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Explain the mechanism of action of Clostridium perfringens toxin
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alpha toxin causes gas gangrene; get double zone of hemolysis on blood agar
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Explain the mechanism of action of C. tetani toxin
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blocks the release of inhibitory neurotransmitters GABA and glycine; causes "lockjaw"
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Explain the mechanism of action of C. botulinum toxin
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Blocks the release of acetylcholine; causes anticholinergic symptoms, CNS paralysis, especially cranial nerves; spores found in canned food, honey (causes floppy baby)
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Explain the mechanism of action of Bacillus anthracis toxin
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Edema factor, part of the toxin complex, is an adenylate cyclase
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Explain the mechanism of action of Shigella toxin
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Shiga toxin (also produced by E. coli O157:H7) cleaves host cell rRNA (inactivates 60S ribosome); also enhances cytokine release, causing HUS
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Explain the mechanism of action of S. pyogenes toxin
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Streptolysin O is a hemolysin; antigen for ASO antibody, which is used in the diagnosis of rheumatic fever
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What are the toxins that induce cAMP?
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V. cholerae toxin (turns "on")
Pertussin toxin (turns "off") E. coli Bacillus anthracis |
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Which toxins are encoded in a lysogenic phage?
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"ABCDE"
ShigA-like toxin, Botulinum toxin, Cholera toxin, Diphtheria toxin, Erythrogenic toxin |