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45 Cards in this Set
- Front
- Back
Top causes of death in low income countries |
Low respiratory infection, HIV, Diarrhea, Malaria |
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Which is the only bacteria to be classified by WHO as a carcinogen? |
Helicobacter pylori |
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What does helicobacter pylori cause. Does it only colonize affected humans? |
Stomach ulcers, 2/3 of humans are colonized and usually asymptomatic |
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The Bacillus Calmette-Guerin is an attenuated strain of x that is used as a vaccine for y What is x, what is y? |
x = mycobacteria y = Tuberculosis (TB) |
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In what cases do individuals confer Mycobacterial dissemination following BCG treatment? |
Genetic defect in some aspect of immunity to infection |
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What bacteria is the cause of Cystic Fibrosis in immunocompromised patients? What type of pathogen does this make it |
Pseudomonas Aeruginosa, opportunistic pathogen |
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What is the direct cause of death of over 50% of AIDS patients worldwide |
Tuberculosis |
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What are the reservoirs for: - Enterohemorrhagic E. Coli, Salmonella and Campylobacter - Clostridium tetani |
- Typhoid Mary (other humans) - Cows - Soil |
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Are there many methods of transport of the bacterial pathogen to the host? |
Airborne, direct contact, the fecal oral route, vehicles that are innanimate (soil, water), living vectors like flies that carry Shigella on their appendages |
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The black death that killed 60% of the european population was caused by what? How was it transmitted? |
Yersisinia pestis through rats |
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What molecule allows bacterial adherence? |
Adhesins |
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What is the difference between adherence and colonization |
Colonization is when a community with its own site of reproduction has been established |
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What do adhesins attach to? |
Proteins, glycoproteins, glycolipids |
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In Listeria monocytogenes, what protein is used to bind mammals. Out of humans, mice and guinea pigs which one is not susceptible, why? |
Internalin, it binds to E-Cadherin Only the mice are not susceptible |
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How does salmonella invade, what type is it? |
They have type 3 infection system where they inject bacterial proteins into the host cell. Other active penetration is between host cells |
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What about passive penetration? |
Not related to pathogen itself e.g. skin lesions and wounds, use existing host pathways of internalization (phagocytosis) |
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What bacterium can grow inside a macrophage |
Mycobacterium |
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What factors allow a bacteria to multiply inside a host? |
Access to nutrients, pH, temperature, redox potential, protection from host attack |
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How to pathogens make it easier for themselves to leave the host? |
Induce symptoms like sneezing, coughing etc otherwise perpetuate through passive mechanisms such as faeces, urine, saliva etc |
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Virulence factors 1: What molecules capture iron for the bacteria |
siderophores |
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Virulence factors 2, what does the capsule do? what is it made of? Give an example |
Made of polysaccharides, protects from phagocytosis Streptococcus Pneumoniae |
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Virulence factors 3: what are exotoxins and endotoxins |
exotoxins secrete the toxin whereas endotoxin is part of the bacterial cell |
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Give an example of the most lethal toxin, which organism it is from, what it does? |
Toxin is called botulinum toxin, from clostricdium botulinium, cleaves a protein involved in the neurotranmission of acetylcholine from motor neurons to muscles |
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How are exotoxins usually inactivated, what type of response can occur from the inactivated toxin |
by heat, triggers immune response |
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Describe the 3 categories of exotoxins (AB, membrane-disrupting, Superantigens) |
AB (A subunit has enzymatic activity while B subunit has binding), membrane-disrupting exotoxins (Not AB, attacks host cell membranes), Superantigens elicit an exaggerated immune response) |
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What are 2 types of membrane-disrupting toxins |
Pore-forming exotoxins and phospholipases (removes polar head groups, destabilizing membrane) |
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What is intoxication How fast is the onset? |
When a disease comes about because the specific preformed toxin enters the host, does not require entry of bacteria Onset is very fast |
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Double vision Droopy Eyelids Slurred Speech Difficulty swallowing Muscle Weakness Are all symptoms of what? |
Botulism |
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Give an example of an endotoxin, |
Gram -ve OM LPS |
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What is the toxic component of endotoxin, are they heat stable? |
Toxic component is Lipid A, and yes is heat stable |
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How does endotoxin work its effects? |
Indirectly - no enzymatic activity on the host, interaction with host cells triggers transcriptional response, increases host cell proteins which produce inflammatory response |
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What are T3SS (Secretion Systems) How many genes is it encoded by? What type of pathogens is it present in |
Molecular Syringe Encoded by roughly 20 genes Resent in gram negative pathogens |
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Between the syringe genes, the injected proteins, and cellular effect, which one is mainly conserved? |
The syringe genes |
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What is T3SS related to? |
Flagellar basal body |
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Salmonella and Yersinia either initiate engulfment or disarm the engulfment system. Which one is what? |
Salmonella initiates, Yersinia disarms |
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What other TXSS exist? |
4 and 6 |
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EHEC - what animal are asymptomatic carries and what did this lead to? |
Cattle are asymptomatic and outbreaks caused massive food recall of 2 million kg |
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What is the infectious dose of EHEC? |
10 cells |
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What percentage... Of EHEC patients develop HUS Of HUS patients develop renal problems Of HUS patients develop neurological symptoms Die of HUS |
0-20% 50% 25% 3-5% |
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What separates EHEC from regular E. coli genetically? |
EHEC contains a T3SS |
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what 4 things does EHEC inject |
1. Tir, becomes a receptor for EHEC binding 2. Other proteins that dissociate tight junctions 3. Other proteins that block phagocytic pathways 4. Other proteins that interfere with host immune signalling |
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Describe the Shiga toxins encoded by EHEC |
Stx1 and Stx2, are AB toxins B binds to glycolipids on host cells (protein is called Gb3) A binds to 60S subunit |
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Where is Gb3 found? Where is it found in cattle? |
Gb3 found in intestinal and kidney epithelium, as well as some neurons Gb3 is not found in cattle |
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EHEC treatment: should you take antibiotics? What about antiperistaltic agents like lomotil? |
No, neither Focus on treating symptoms |
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Example 2: Salmonella Typhimurium Where does it live w.r.t. host cells? What does its 2 T3SSs do? |
Lives within host cells One for invasion of host cell, other one for survival |