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18 Cards in this Set
- Front
- Back
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Alterations in normal body bacteria flora... |
→ in immune dysfunction |
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C. diff is associated with... |
Antibiotic Associated Colitis |
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Bacteria |
Prokaryotes lack a nucleus no membrane bound organelles slimy capsule |
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Gram stain explain the process? |
1. stain with crystal violet + iodine 2. wash the cells with iodine 3. counterstain with safranin 4. if they retain the crystal violet + iodine = Purple, Gram Positive 5. if they retain the safranin = Pink, Gram Negative |
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Gram positive bacteria type of layers on cell membrane? thickness of cell membrane? |
Peptidoglycan only Thick cell wall |
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Gram negative bacteria type of layers on cell membrane? thickness of cell membrane? |
Peptidoglycan + Lipopolysaccharide LPS or Endotoxin Thin cell wall outer layer heavily modified with sugars |
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LPS what is it? |
potent activator of the immune system → endotoxic shock e.g. meningococcal sepsis |
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Peptidoglycan cell wall implications for treatment? |
target for many ABX etc. |
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MALDI-TOF MS technique? what does it allow you to do? |
Matrix Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry expose bacteria colony from sample e.g. stool, CSF, analysis of mass of fragmentation → identification of organisms by a database |
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How Bacteria → Disease: Overview |
1. Attach to host 2. Invade tissue 3. Acquire nutrients and grow 4. Avoid host immune response 5. cause damage - presents as the signs and symptoms of disease |
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Virulence factors what is the definition? |
factors that allow pathogens to cause disease |
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How Bacteria → Disease: Attachment |
Pili/Fimbrae by attaching to host receptors can be taken up then intracellular survival occurs |
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E. Coli is an intracellular bacteria |
E. Coli expresses FimH which means it evades phagocytosis |
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How Bacteria → Disease: Invasion Type 3 secretions what is it? example bacterium? |
Type 3 Secretions: https://www.youtube.com/watch?v=gnNFNI9_pT0 injects host cell with effector molecules → alter cytoskeleton of cell → promotes bacteria uptake e.g. salmonella |
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How Bacteria → Disease: Invasion Nutrient acquisition e.g. Fe |
Nutrient acquisition - acquiring Fe most Fe is bound to transferrin bacteria make siderophores have high affinity for Fe and scavenge it from host proteins |
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How Bacteria → Disease: Invasion Mechanism of Immune evasion |
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How Bacteria → Disease: Damage Direct mechanism... Indirect mechanism... |
Direct - via toxins e.g. membrane damaging, neurotoxins, tetanus, botulinum Indirect - over activation of inflammation e.g. LPS over activation of cytokines in sepsis, Molecular mimicry - microbial components are similar to host e.g. Group A Streptococci, Acute Rheumatic fever |
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CLINICAL APPLICATION: Toxic Shock Syndrome |
When Staphylococcal aureus toxin → toxic shock |
