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Foundations of Medicine > Bacteria > Flashcards

Bacteria Flashcards

1
Q

What are the features of bacteria?

A 
Capsule 
Cell Wall 
Flagellum 
Membrane 
Ribosome 
Single chromosomes 
Spores
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2
Q

What is the function of the cell wall of a bacteria?

A

Prevents the cell wall from bursting (preventing lysis)

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3
Q

What are the two types of cell membrane

A
  • Gram negative. Lipopolysaccharides are used to protect peptidoglycans from bile salts and lysozyme. They may prevent antibiotics from getting into the cell. They contain lipid A which if released causes endotoxic shock.
  • Gram positive
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4
Q

What colours do the two types of cell membrane stain ?

A

Gram negative - Red

Gram positive - Purple

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5
Q

How do bacteria replicate ?

A

Binary fission

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6
Q

How is genetic variation created in bacteria?

A

Mutations and transfer of DNA.

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7
Q

How can bacteria be classified?

A

Phenotypically - Gram stain

Genotypically - Ribosomal RNA sequence or whole gene sequencing

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8
Q

How are bacteria named?

A

The first half is based on the genius of the bacteria and the second half is based on the species of the bacteria.

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9
Q

How can a strain of bacteria be identified?

A

DNA typing techniques

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10
Q

What are the different shapes bacteria can come in ?

A

Cocci (Spheres)
Bacilli (Rods)
Spirals

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11
Q

What are sensitive and resistant bacteria?

A

Sensitive means that the bacteria is killed or inhibited by X.
Resistant means that the bacteria is not killed or inhibited by X.

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12
Q

What does bactericidal mean?

A

A antimicrobial that kills a bacteria.

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13
Q

What is a MBC ?

A

Minimum concentration of a antimicrobial needed to kill an organism.

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14
Q

What does bacteriostatic mean?

A

A antimicrobial that inhibits a bacteria.

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15
Q

What is a MIC?

A

The minimum concentration of an antimicrobial needed to inhibit the growth of given organism.

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16
Q

In what ways can antibiotics be administered?

A

Topical (Onto the skin or mucous membrane)
Systemic (orally)
Parental (IV or IM and subcutaneously)

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17
Q

What are the three ways in which antibiotics work?

A
  • Inhibition of the cell wall
  • Inhibition of protein synthesis
  • Inhibition of nucleic acid synthesis.
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18
Q

What two antibiotics can carry out inhibition of the cell wall?

A

B-lactams bactericidal antibiotics.

Glycopeptide bactericidal antibiotics

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19
Q

How do B lactams work?

A

They work on gram positive bacteria. They disrupt peptidoglycan synthesis by inhibiting enzymes responsible for cross-linking the carbohydrate chains.

20
Q

How do glycopeptides work ?

A

They work on gram positive bacteria. They inhibit the assembly of the peptidoglycan precursors. Parental use only.

21
Q

What are examples of Glycopeptides ?

A

Vancomycin - IV

Teicoplanin - Single daily dose.

22
Q

What are the different types of antibiotics which inhibit protein synthesis?

A 
Aminoglycosides bactericidal (Gram neg)
Macrolides Bactericidal or bacteriostatic (gram pos)
Tetracyclines bacteriostatic (gram pos)
Oxazolidinones Bactericidal or bacteriostatic (gram pos)
Cyclic lipopeptide strong bactericidal (gram pos)
23
Q

What are aminoglycosides used for ?

A

Gram negative bacteria. Premature termination or misreading of RNA. Parental use only.

24
Q

Example of aminoglycosides

A

Gentamicin (Cheap and effective) but you have to monitor serum levels.

25
Q

What are macrolides used for?

A

Gram positive. Alternative to penicillin. Prevent adding of more amino acids and inhibit ribosomal translation.

26
Q

Example of macrolides are ?

A

Erythromycin, azithromycin (good for single doses) and clarithromycin

27
Q

What are tetracyclines used for?

A

Gram positive. Prevent tRNA attachment to the ribosome.

28
Q

What are oxazolidinones used for?

A

Gram positive. No formation of initiation complex.

29
Q

Example of oxazolidinones

A

Linezolid.

30
Q

What are cyclin lipopeptide strong antibiotics used for?

A

Gram positive. Create holes in the membrane.

31
Q

Example of cyclin lipopeptide strong

A

Daptomycin

32
Q

What are the different types of antibiotic that inhibits nucleic acid synthesis?

A

Inhibition in purine synthesis. Bacteriostatic.

Fluroquinolones. Bactericidal.

33
Q

How do inhibitors in purine synthesis work ? Quinolones.

A

Inhibit DNA synthesis.

Useful against gram negative

34
Q

How do fluroquinolones work?

A

Gram negative

Inhibit DNA synthesis.

35
Q

What are some adverse side effects to antibiotics?

A 
Allergenic reactions (after to B lactams)
Immediate hypersensitivity 
Delayed hypersensitivity 
Gastrointestinal 
Thrush 
liver toxicity 
Renal toxicity 
neurological toxicity 
Haematological toxicity (Bone)
36
Q

How can you prevent adverse reactions to antimicrobials?

A

Only use when necessary
Use the minimum dose
Make sure it is safe to administer the dose i.e. Check if a women is pregnant etc

37
Q

examples of antibiotics that are safe in pregnancy

A

Penicillin’s

38
Q

What are the two types of antimicrobial resistance ?

A
  • Inherent or intrinsic. When in every case that micro-organism is resistant to that antimicrobial
  • Acquired. When resistant may be present in some strains but not in others.
39
Q

Describe how some bacteria become resistant to B lactams

A

B-lactamases are enzymes that are produced by bacteria and which remove the B lactam ring from the antibiotics making it useless.

40
Q

How can B lactamases be combated?

A
  • Add a inhibitor i.e. clavulanic acid

- Add a component to prevent the action of the B lactamases. i.e. flucloxacillin

41
Q

What are the three ways in which bacteria acquiring antimicrobial resistance?

A

Conjugation - DNA transferred through a join of bacteria
Transduction - Bacteria is transferred by viruses
Transformation - DNA is released from one bacteria and taken up by another

42
Q

What are prophylaxis?

A

Antimicrobials given in anticipation of infection i.e. after surgery.

43
Q

What is the delivery system of antimicrobials

A

Normally monotherapy but sometimes combinations are necessary.

44
Q

What are the possible outcomes of antimicrobials being used in combination ?

A
  • The effect is additive

- There effect is Synergistics (Greater than there sum)

45
Q

What is a susceptibility test?

A

A test used to determine the MIC.

46
Q

What antibiotics can be used against gram negative bacteria

A

Inhibition in purine synthesis. Bacteriostatic.
Fluroquinolones. Bactericidal.
Aminoglycosides bactericidal.

Foundations of Medicine (25 decks)

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