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17 Cards in this Set
- Front
- Back
Bugs that do not Gram stain well (6).
What other stains must be used? |
"These Rascals May Microscopically Lack Color."
1. Treponema - darkfield microscopy; fluorescent ab stain 2. Rickettsia - intracellular parasite 3. Mycobacteria - high-lipid wall (mycolic acid); acid-fast stain 4. Mycoplasma - no cell wall (sterols) 5. Legionella - primarily intracellular; silver stain 6. Chlamydia - intracellular; no muramic acid in cell wall |
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Non-Gram stains (5).
What bugs do they stain? |
1. Giemsa: Chlamydia, Borrelia, Plasmodium, trypanosomes
2. PAS (periodic acid-Schiff): glycogen, mucopolysaccharides; Tropheryma whippelii (Whipple's disease) 3. Ziehl-Neelsen: acid-fast organisms 4. Indian ink: Cryptococcus neoformans (may also use mucicarmine to stain thick polysacch capsule red) 5. Silver stain: fungi (e.g. Pneumocystis), Legionella |
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Obligate aerobes (4).
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"Nagging Pests Must Breathe."
1. Nocardia 2. Pseudomonas aeruginosa (burns, nosocomial pneumonia, CF pneumonia) 3. Mycobacterium tuberculosis 4. Bacillus |
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Obligate anaerobes (3).
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"Can't Breathe Air."
1. Clostridium 2. Bacteroides 3. Actinomyces Lack catalase and/or superoxide dismutase. Foul-smelling (short-chain fatty acids), produce CO2 or H2 gas in tissue, AminO2glycosides ineffective because they require O2 to enter into bacterial cell. |
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Intracellular bugs, obligate (2).
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"Stay inside when it's Really Cold."
1. Rickettsia 2. Chlamydia Obligate intracellular bugs can't make own ATP. |
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Intracellular bugs, facultative (7).
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"Some Nasty Bugs May Live FacultativeLy."
1. Salmonella 2. Neisseria 3. Brucella 4. Mycobacterium 5. Listeria 6. Francisella 7. Legionella |
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Encapsulated bacteria (5).
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"Kapsules Shield SHiN."
1. Klebsiella 2. Salmonella 3. Strep. pneumo 4. H. influenza (B polysaccharide) 5. Neisseria meningitidis SHiN can produce IgA protease, cause meningitis, and take up DNA from environment (transformation). |
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Urease-positive bugs (4).
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"Particular Kinds Have Urease."
1. Proteus 2. Klebsiella 3. H. pylori 4. Ureaplasma |
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Pigment-producing bugs (4).
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1. Actinomyces israelii: yellow "sulfur" granules ("Israel has yellow sand")
2. Staph. aureus: yellow pigment (Latin aureus = "gold") 3. Pseudomonas aeruginosa: blue-green pigment ("AERUGula is green") 4. Serratia marcescens: red pigment ("Red maraschino cherries") |
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Bacterial virulence factors (3).
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1. Protein A, Staph. aureus: binds Fc region of Ig, preventing opsonization and phagocytosis.
2. IgA protease: secreted by SHiN to colonize respiratory mucosa. 3. M protein, group A Strep: helps prevent phagocytosis |
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Compare exotoxin and endotoxin.
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Exotoxin is secreted; endotoxin isn't.
Exotoxin genese are in plasmid or bacteriophage; endotoxin genes are in chromosome. Exotoxin is highly toxic; endotoxin isn't. Exotoxin has various effects and actions; endotoxin induces fever, shock, and causes TNF and IL-1 to be released. Exotoxin is highly antigenic; endotoxin isn't. Thus, exotoxin can be vaccinated against; endotoxin can't. Exotoxin is fragile (destroyed at 60C); endotoxin isn't. |
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What is the only gram-positive bug with endotoxin?
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Listeria
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Name the diseases associated with exotoxin (3) and endotoxin (2).
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Exotoxin:
1. Tetanus 2. Botulism 3. Diphtheria Endotoxin: 1. Meningococcemia 2. Sepsis by GNR |
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How do superantigens work?
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Bind directly to MHC II and T-cell receptor simultaneously, activating large numbers of T cells to stimulate release of IFN-gamma and IL-2.
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Name two bugs with superantigens.
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1. Staph. aureus: TSST-1 causes toxic shock syndrome (fever, rash shock); exfoliatin causes scalded skin syndrome; heat-stable enterotoxins cause food poisoning
2. Strep. pyogenes: erythrogenic toxin causes Scarlet fever, similar to toxic shock |
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What are some properties of SHiN?
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1. Encapsulated: antiphagocytic
2. IgA protease: allows respiratory mucosa colonization 3. Transformation/competence: allows uptake of DNA from environment |
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Name the ADP ribosylating A-B exotoxins (4).
Recall: B binds cell surface receptor, A performs ADP-ribosylation to alter host protein function. |
1. C. diphtheria: inactivates EF-2, similar to Pseudomonas exotoxin A
2. Vibrio cholerae: ADP-ribosylates G protein to stimulate adenylyl cyclase, extrude Cl- and fail to absorb Na+ (H2O into gut lumen, rice water diarrhea!) 3. E. coli (heatl-labile stimulates adenylate cyclase, heat-stable stimulates guanylate cyclase: "Labile like the Air, stable like the Ground") 4. Bordetella pertussis: increases cAMP by inhibiting G-alpha, inhibits chemokine receptor causing lymphocytosis |