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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

Which is the only bacteria to be classified by WHO as a carcinogen?

Helicobacter pylori

What does helicobacter pylori cause. Does it only colonize affected humans?

Stomach ulcers, 2/3 of humans are colonized and usually asymptomatic

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)

In what cases do individuals confer Mycobacterial dissemination following BCG treatment?

Genetic defect in some aspect of immunity to infection

What bacteria is the cause of Cystic Fibrosis in immunocompromised patients? What type of pathogen does this make it

Pseudomonas Aeruginosa, opportunistic pathogen

What is the direct cause of death of over 50% of AIDS patients worldwide

Tuberculosis

What are the reservoirs for:
- Salmonella Typhi


- Enterohemorrhagic E. Coli, Salmonella and Campylobacter


- Clostridium tetani

- Typhoid Mary (other humans)


- Cows


- Soil

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

The black death that killed 60% of the european population was caused by what? How was it transmitted?

Yersisinia pestis through rats

What molecule allows bacterial adherence?

Adhesins

What is the difference between adherence and colonization

Colonization is when a community with its own site of reproduction has been established

What do adhesins attach to?

Proteins, glycoproteins, glycolipids

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

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

What about passive penetration?

Not related to pathogen itself e.g. skin lesions and wounds, use existing host pathways of internalization (phagocytosis)

What bacterium can grow inside a macrophage

Mycobacterium

What factors allow a bacteria to multiply inside a host?

Access to nutrients, pH, temperature, redox potential, protection from host attack

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

Virulence factors 1: What molecules capture iron for the bacteria

siderophores

Virulence factors 2, what does the capsule do? what is it made of?


Give an example

Made of polysaccharides, protects from phagocytosis


Streptococcus Pneumoniae

Virulence factors 3: what are exotoxins and endotoxins

exotoxins secrete the toxin whereas endotoxin is part of the bacterial cell

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

How are exotoxins usually inactivated, what type of response can occur from the inactivated toxin

by heat, triggers immune response

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)

What are 2 types of membrane-disrupting toxins

Pore-forming exotoxins and phospholipases (removes polar head groups, destabilizing membrane)

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

Double vision


Droopy Eyelids


Slurred Speech


Difficulty swallowing


Muscle Weakness




Are all symptoms of what?

Botulism

Give an example of an endotoxin,

Gram -ve OM LPS

What is the toxic component of endotoxin, are they heat stable?

Toxic component is Lipid A, and yes is heat stable

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

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

Between the syringe genes, the injected proteins, and cellular effect, which one is mainly conserved?

The syringe genes

What is T3SS related to?

Flagellar basal body

Salmonella and Yersinia either initiate engulfment or disarm the engulfment system. Which one is what?

Salmonella initiates, Yersinia disarms

What other TXSS exist?

4 and 6

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

What is the infectious dose of EHEC?

10 cells

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%

What separates EHEC from regular E. coli genetically?

EHEC contains a T3SS

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

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

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

EHEC treatment: should you take antibiotics? What about antiperistaltic agents like lomotil?

No, neither


Focus on treating symptoms

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