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Year 1 Medicine > Bacteria > Flashcards

Bacteria Flashcards

1
Q

What is the purpose of flagellum?

A

Aid motility of the bacterium

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2
Q

Do bacteria have a nucleus?

A

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

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3
Q

What is the function of Fimbriae?

A

Aids attachment and adherence to other cells.

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4
Q

What colour do gram positive bacteria stain?

A

Purple.

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5
Q

What colour do gram negative bacteria stain?

A

Pink

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6
Q

What shape is cocci?

A

Spherical

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7
Q

What shape is bacilli?

A

Rod shaped

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8
Q

What is the function of the capsule?

A

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

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9
Q

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

A

Monotrichous

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10
Q

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

A

Lophotrichous

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11
Q

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

A

Amphitrichous

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12
Q

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

A

Peritrichous

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13
Q

What are spores?

A

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

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14
Q

What are Plasmids?

A

Extra chromosomal entities out with the chromosome itself.

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15
Q

How do bacteria replicate?

A

Binary fission, producing identical progeny.

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16
Q

How do bacteria achieve genetic variation?

A

Spontaneous mutation and the transfer of DNA.

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17
Q

What is conjugation?

A

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

18
Q

What is transduction?

A

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

19
Q

What signs and symptoms characterise clinical infection?

A 
Inflammation
Pain
Pyrexia (increase in temp)
Tachycardia 
Rigors
Increased white cell count
Increased C reactive protein.
20
Q

What is a pathogen?

A

An organism which can cause disease.

21
Q

What is a commensal?

A

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

22
Q

What is pathogenicity?

A

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

23
Q

What is infectivity?

A

Ability to become established.

24
Q

What is virulence?

A

Ability to cause harmful effects once established.

25
Q

How to pathogens become established within a host?

A

Attachment - e.g E.coli attach by P-fimbriae and receptors on uroepithelial cells.

Acid resistance - Helicobacter pylori uses urease (ammonia from urea)

26
Q

What are some virulence factors?

A

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

27
Q

How are Exotoxins released?

A

Released extracellularly by the micro-organism

28
Q

What are Enterotoxins?

A

Special form of exotoxins that work on the GI tract.

29
Q

What is an Endotoxin?

A

Structurally part of a gram negative cell wall.

30
Q

Give an example of an exotoxin?

A

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

31
Q

Give an example of an enterotoxin?

A

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

32
Q

What are superantigens?

A

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.

33
Q

How do endotoxins affect the body?

A

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.

34
Q

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

A

Acinetobacter baumannii
Pseudomonas aeruginosa
Enterobacteriaceae

35
Q

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

A 
Enterococcus faecium
Staphylococcus aureus
Helicobacter pylori
Campylobacter
Salmonella
Neisseria gonorrhoeae
36
Q

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

A

Streptococcus pneumoniae
Haemophilus influenzae
Shigella

37
Q

What are some common gram positive bacteria?

A

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

38
Q

What is staph. aureus commonly resistant to?

A

Penicillin due to production of penicillinase.

39
Q

Give some characteristics of coagulase-negative staphylococci?

A

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

40
Q

Give some examples of Streptococci sub species?

A

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

41
Q

Name some examples of gram positive bacilli?

A

Clostridium difficile
Clostridium perfringens
Clostridium tetani

42
Q

What are some characteristics of Clostridium difficile?

A

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

Year 1 Medicine (37 decks)

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