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Flashcards in Microbiology 3: bacteria Deck (100)
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1

structural difference in organisation of cell contents between bacteria and eukaryotic cells

Bacteria do not have organelles (different to eukaryotes)

2

Outline the location of DNA in bacteria

hey just have their genetic material and ribosomes floating in the cytoplasm, as well as a cell wall

3

What kind of appendages coul dbacteria have? Does this affec virulence

Hypha/stalks Yes may do

4

Normal 3 tpes of naceria

Cocci, bacilli, spiral

5

List the common virulence features for bacteria

Diverse secretion systems, Flagella (movement, attachment), Pili (important adherence factors), Capsule (protect against phagocytosis) i.e. Streptococcus pneumoniae ,Endospores (metabolically dormant forms of bacteria) heat, cold, desiccation and chemical resistant i.e. Bacillus sp. and Clostridium sp. Biofilms Exotoxin Endotoxin

6

How does flagella and pili contribute to virulence

Flagella (movement, attachment) Pili (important adherence factors)

7

How does capsule contribute to virulence Example

Capsule (protect against phagocytosis) i.e. Streptococcus pneumoniae

8

How does endospores contribute to virulence Examle

Endospores (metabolically dormant forms of bacteria) heat, cold, desiccation and chemical resistant i.e. Bacillus sp. and Clostridium sp.

9

How does biofilms contribute to virulence. Examples

(organized agregrates of bacteria embedded in polysaccahride matricesi. e. Pseudomonas aeruginosa i.e. Staphylococcus epidermidis

10

3 types of exotoxin

Neurotoxin Enterotoxin Tissue invasive exotoxin Miscellaneous exotoxin Pyrogenic exotoxin

11

Outline neurotoxin wiht examples

act on nerves or motor endplate i.e. Tetanus or Botulinum toxins

12

Outline 2 types of enterotoxin withexamples

1. Infectious diarrhea Vibrio cholera, Escherichia coli, Shigella dysenteriae and Campylobacter jejuni 2. Food poisoning Bacillus cereus or Staphylcoccus aureus

 THEY ACT ON THE GI TRACT

13

Outline pyrogenic exotoxins

Stimulate cytokine release Staphylcoccus aureus or Streptococcus pyogenes

14

Outline Tissue invasive exotoxin

allow bacteria to destroy and tunnel through tissue i.e. Staphylococcus aureus, Streptococcus pyogenes Clostridium perfringens

15

Which enzymes might tissue invasive exotoxin involve

enzymes that destroy DNA, collagin, fibrin, NAD, red or white blood cells

16

Examples of miscellaneous exotoxin, and what is different about them

specific to a certain bacterium and/or function not well understood Bacillus anthracis and Corynebacterium diphtheriae

17

What is endotoxin released by

Only produced by Gram-negative bacteria

18

What is endotoxin

Not a protein but it's the the lipid A moiety of LPS

19

Differentiate gram positive and gram negative

Gram +ve= big cell wall, 1 lipid bilayer Gram -ve= small cell wall, 2 lipid bilayers

20

What is seen on the lipid bilayer of

On the lipid bilayer of gram negative bacteria, we see LPS and sugars – these are endotoxins

21

What can happen if lots of the LPS is shed

Then it can cause endotoxic shock Normally shed in steady amounts

22

Why can giving antibiotics to gram neg bacteria be dangerous

when bacteria lyse they release large quantities of LPS/ Endotoxin Leads to septic shock

23

Define septic shock

Sepsis that results in dangerous drops in blood pressure and organ dysfunction is called septic shock. It is also referred to as endotoxin shock because endotoxin often triggers the immune response that results in sepsis and shock.

24

Differentiate endotoxin shock and septic shock

different effectors molecules in Gram-positive bacteria or even fungi can trigger this adverse immune response – so the term septic shock is inclusive (of endotoxin shock and other shocks too)

25

What is haemolytic-uraemic syndrome

triad of acute renal failure, hemolytic anemia and thrombocytopenia

26

What usually causes haemolytic-uraemic syndrome

Shiga toxin producing E. coli strain

27

Define outbreak

An outbreak is a greater-than-normal or greater-than-expected number of individuals infected or diagnosed with a particular infection in a given period of time, or a particular place, or both.

28

What are E.coli strains which release shiga toxin known as

EHEC enterohemorrhagic E. coli

29

Reservoirs for EHEC

reservoir are normally ruminants – mostly cattle

30

When does human infection with EHEC often occur

occurs through the inadvertent ingestion of fecal matter and secondary through contact with infected humans