Bacteria

Question 1

What is the purpose of flagellum?

Answer 1

Aid motility of the bacterium

Question 2

Do bacteria have a nucleus?

Answer 2

No they contain a single chromosome. And sometimes extra DNA within a plasmid.

Question 3

What is the function of Fimbriae?

Answer 3

Aids attachment and adherence to other cells.

Question 4

What colour do gram positive bacteria stain?

Answer 4

Purple.

Question 5

What colour do gram negative bacteria stain?

Answer 5

Pink

Question 6

What shape is cocci?

Answer 6

Spherical

Question 7

What shape is bacilli?

Answer 7

Rod shaped

Question 8

What is the function of the capsule?

Answer 8

Virulence factor - aids the bacterial survival in the host by preventing phagocytosis.

Question 9

What is the name given to a bacteria with a single flagella?

Answer 9

Monotrichous

Question 10

What is the name given to multiple flagella that originate from one point on a bacteria?

Answer 10

Lophotrichous

Question 11

What is the name given to bacteria that have a flagellum coming out from either side of it?

Answer 11

Amphitrichous

Question 12

What name is given to bacteria that have flagellum all over it?

Answer 12

Peritrichous

Question 13

What are spores?

Answer 13

Highly resistive, dormant structures produced by bacteria that allow it to survive in extreme conditions. Common in gram positive bacteria.

Question 14

What are Plasmids?

Answer 14

Extra chromosomal entities out with the chromosome itself.

Question 15

How do bacteria replicate?

Answer 15

Binary fission, producing identical progeny.

Question 16

How do bacteria achieve genetic variation?

Answer 16

Spontaneous mutation and the transfer of DNA.

Question 17

What is conjugation?

Answer 17

Sex between 2 bacteria using a pilus to transfer a plasmid from one to the other.

Question 18

What is transduction?

Answer 18

The process of phage DNA integrating with the DNA of the bacteria. Tail and endplate provide grip throughout this process.

Question 19

What signs and symptoms characterise clinical infection?

Answer 19

Inflammation
Pain
Pyrexia (increase in temp)
Tachycardia 
Rigors
Increased white cell count
Increased C reactive protein.

Question 20

What is a pathogen?

Answer 20

An organism which can cause disease.

Question 21

What is a commensal?

Answer 21

An organism which is part of normal flora e.g E.coli in gut.

Question 22

What is pathogenicity?

Answer 22

The capacity of a micro-organism to cause an infection.. It requires infectivity and virulence.

Question 23

What is infectivity?

Answer 23

Ability to become established.

Question 24

What is virulence?

Answer 24

Ability to cause harmful effects once established.

Question 25

How to pathogens become established within a host?

Answer 25

Attachment - e.g E.coli attach by P-fimbriae and receptors on uroepithelial cells. Acid resistance - Helicobacter pylori uses urease (ammonia from urea)

Question 26

What are some virulence factors?

Answer 26

Genetically determined microbial components: Invasiveness Toxin production Evasion of immune system

Question 27

How are Exotoxins released?

Answer 27

Released extracellularly by the micro-organism

Question 28

What are Enterotoxins?

Answer 28

Special form of exotoxins that work on the GI tract.

Question 29

What is an Endotoxin?

Answer 29

Structurally part of a gram negative cell wall.

Question 30

Give an example of an exotoxin?

Answer 30

Tetanus released by Clostridium tetani. The toxin binds to nerve synapses and inhibits the release of inhibitory neurotransmitters.

Question 31

Give an example of an enterotoxin?

Answer 31

Cholera released by vibrio cholerae. Toxin increases CAMP levels. Inhibits uptake of Na+ and Cl- ions Stimulates secretion of Cl- and HCO3- ions Passive (massive) outflow of H2O Causes death by dehydration

Question 32

What are superantigens?

Answer 32

Exotoxins of Strep pyogenes and Staph aureus. Able to stimulate the division of T cells in the absence of specific antigen. Results in overwhelming cytokine production which causes toxic shock.

Question 33

How do endotoxins affect the body?

Answer 33

Induces severe uncontrolled host response: Cytokine production Fever, rigors, hypotension, tachycardia, collapse Present in E.coli and other gram negative bacteria. Lipid A is the nasty part.

Question 34

Give some examples of bacteria that are considered critical threat to humans?

Answer 34

Acinetobacter baumannii Pseudomonas aeruginosa Enterobacteriaceae

Question 35

Give some examples of bacteria that are considered high risk to humans?

Answer 35

``` Enterococcus faecium Staphylococcus aureus Helicobacter pylori Campylobacter Salmonella Neisseria gonorrhoeae ```

Question 36

Give some examples of bacteria that are considered medium risk to humans?

Answer 36

Streptococcus pneumoniae Haemophilus influenzae Shigella

Question 37

What are some common gram positive bacteria?

Answer 37

Staphylococci and Streptococci and Enterococci (chains) E.g Staph . aureus Strep . pneumoniae

Question 38

What is staph. aureus commonly resistant to?

Answer 38

Penicillin due to production of penicillinase.

Question 39

Give some characteristics of coagulase-negative staphylococci?

Answer 39

Mainly skin commensals Form biofilms and may be significant pathogens in the presence of foreign bodies/prostheses e.g. prosthetic heart valves etc or immunocompromised e.g. neonates

Question 40

Give some examples of Streptococci sub species?

Answer 40

α- haemolytic (par@al haemolysis) - turn blood agar green e.g strep. pneumoniae • β-haemolytic (complete haemolysis) - turn blood agar clear e.gFurther identified by carbohydrate surface antigens • Non haemolytic - group A e.g Streptococcus pyogenes group B e.g Streptococcus agalactiae

Question 41

Name some examples of gram positive bacilli?

Answer 41

Clostridium difficile Clostridium perfringens Clostridium tetani

Question 42

What are some characteristics of Clostridium difficile?

Answer 42

Difficult to culture Important cause of diarrhoea, associated with toxin production, potentially fatal Increased risk with antibiotic use. Spreads via spores.