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Path Y > Microbiology - Antimicrobial Agents 1 > Flashcards

Microbiology - Antimicrobial Agents 1 Flashcards

1
Q

What 3 groups of antibiotics are classified as beta lactams?

A

Penicillins
Cephalosporins
Carbapenems

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2
Q

Name 2 glycopeptide antibiotics

A

Vancomycin

Teicoplanin

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3
Q

Describe the mechanism of action of beta lactams

A

Inhibits transpeptidase, which is an enzyme that forms cross links during the formation of the cell wall.
The resulting cell wall is therefore weak, and so the bacteria lyse because of osmotic pressure.

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4
Q

How does the cell wall of gram pos and gram neg bacteria differ?

A

Gram pos has thick peptidoglycan in cell wall

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5
Q

What bacteria is penicillin active against?

A

Gram positive

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6
Q

What bacteria is amoxicillin active against?

A

Broad spectrum: gram pos and many gram neg

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7
Q

Is streptococci gram pos or neg?

A

Gram pos

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8
Q

Which beta lactam antibiotic is effective against pseudomonas?

A

Piperacillin

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9
Q

How can beta lactam resistance be overcome? Give 2 examples of drugs?

A

Include a beta lactamase inhibitor

  • Clavulanic acid + amoxicllin (in co-amoxiclav)
  • Tazocin (piperacillin & tazobactam)
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10
Q

Is pseudomonas gram pos or gram neg?

A 
Gram neg
(Pseudo"moan"as - 'moan' = negative)
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11
Q

Is neisseria meningitis gram pos or gram neg?

A 
Gram neg
(Neisseria starts with N = negative)
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12
Q

Recall an antibiotic that is associated with C. difficile

A

Ceftriaxone (cephalosporin)

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13
Q

Which beta lactam antibiotics are used to treat to ESBL producing organisms?

A

Carbapenems

as ESBL producing organisms are resistant to cephalosporins

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14
Q

recall a caution of beta lactam antibiotic. do they cross the BBB?

A

Excreted renally so reduce dose if renal impairment

do not cross BBB

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15
Q

What type of bacteria are glycopeptides effective against?

A

Gram pos only - they are large molecules so can’t penetrate gram neg cell wall

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16
Q

What 2 infections are glycopeptides particularly useful for?

A

MRSA infection

C difficile

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17
Q

What is a caution of glycopeptide antibiotics?

A

They are nephrotoxic

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18
Q

Recall the broad mechanism of action of glycopeptide antibiotics

A

Prevent peptide cross links in cell wall

inhibit cell wall synthesis

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19
Q

Recall the broad mechanism of action of aminoglycosides

A

Bind to 30s ribosomal subunit, preventing elongation of polypeptide chain
(inhibit protein synthesis)
-bactericidal

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20
Q

Recall 2 examples of aminoglycoside antibiotics

A

gentamicin

amikacin

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21
Q

What type of bacteria are aminoglycoside antibiotics effective against?

A

Gram neg

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22
Q

Recall 2 toxicities of aminoglycosides

A

Ototoxicity

Nephrotoxicity

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23
Q

What type of bacteria are macrolides effective against?

A

Gram pos

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24
Q

What are macrolides particularly useful for?

A

Mild staph or strep infections in patients who are allergic to penicillin

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25
Q

Recall 3 macrolide antibiotics

A

Azithromycin
Clarithromycin
Eryhromycin

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26
Q

What type of bacteria are tetracylines effective against?

A

broad spectrum - intracellular organisms

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27
Q

Recall a class of antibiotic you should never give to children or pregnant women

A

Tetracyclines

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28
Q

Recall one side effect of tetracycline antibiotics

A

photosensitivity rash (summer effect)

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29
Q

Recall the broad mechanism of action of macrolides

A

Bind to the 50s subunit of ribosomes

bacteriostatic

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30
Q

Recall the broad mechanism of action of tetracyclines

A

Bind to 30s subunit of ribosomes

bacteriostatic

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31
Q

What type of bacteria is chloramphenicol effective against?

A

Many - it is v broad spectrum

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32
Q

Why is chloramphenicol rarely used?

A

Risk of aplastic anaemia and grey baby syndrome in neonates due to inability to metabolise drug

33
Q

Recall 2 specific bacteria that macrolides are effective against

A

Campylobacter sp

Legionella pneumophila

34
Q

Recall the broad mechanism of action of chloramphenicol

A

Binds to 50s subunit of ribosomes - inhibits formation of peptide bonds during translation
-bacteriostatic

35
Q

Recall the broad mechanism of action of oxazolidinones

A

Binds to the 23s component of 50s subunit of ribosomes to prevent 70s subunit formation

36
Q

Recall two types of bacteria that oxazolidinones are particularly active against

A

MRSA and VRE (vancomycin resistant enterococci)

37
Q

Recall an example of oxazolidinones

A

Linezolid

38
Q

Recall 2 potential side effects of oxazolidinones

A

Thrombocytopaenia & optic neuritis

39
Q

Recall the broad mechanism of action of fluoroquinolones

A

Act on alpha subunit of DNA gyrase
(inhibit DNA synthesis)
- bactericidal

40
Q

Recall 4 uses of fluoroquinolones

A

UTI
Pneumonia
Atypical pneumonia
Bacterial gastroenteritis

41
Q

Recall 2 examples of fluoroquinolone antibiotics

A

Levofloxacin

Moxifloxacin

42
Q

Give an example of a nitroimidazole antibiotic

A

Metronidazole

43
Q

Recall types of organisms that metronidazole is effective against

A

Anaerobes

Protozoa

44
Q

When should metronidazole be taken?

A

Right after visiting the toilet as it sits in bladder

45
Q

Recall the broad mechanism of action of rifamycins

A

Binds to DNA-dependent RNA polymerase to inhibit RNA synthesis
example is rifampicin

46
Q

Recall the main use of rifampicin

A

TB treatment

47
Q

Recall one side effect of rifampicin

A

Turns secretions orange

48
Q

Recall one condition of rifampicin prescription

A

Should never be prescribed alone as resistance develops very quickly

49
Q

Colistin is very toxic. Why is it coming back into use?

A

It is active agianst certain multi-drug resistant bacteria

50
Q

What is daptomycin licensed for the treatment of?

A

MRSA

VRE

51
Q

Recall the 2 classes of antibiotic that inhibit folate synthesis

A

Sulphonamides

Diaminopyrimidines

52
Q

Give an example of a sulphonamide

A

sulfamethoxazole

53
Q

What is the main use of trimethoprim

A

Uncomplicated UTI

54
Q

What are the 4 main mechanisms of resistance? Give examples

A

BEAT drug action

  1. Bypass antibiotic sensitive step in pathway e.g MRSA
  2. Enzyme mediated drug inactivation e.g beta lactamases
  3. Impairment of accumulation of the drug e.g tetracyclines
  4. Modification of the drugs target in the microbe e.g quinolone
55
Q

Which antibiotic is best for treating pneumocystis jiroveci pneumonia?

A

this is a HIV defining disease

sulphamethoxazole + trimethoprim (co-trimoxazole)

56
Q

What is the broad mechanism of action of nitroimidazoles?

A

Inhibit DNA synthesis

57
Q

Which bacteria typically forms “gram pos cocci in clusters”?

A

Staphylococcus

58
Q

Which bacteria typically forms “gram pos cocci in chains”?

A

Streptococcus

Strep sounds like ‘stripe’ = chain

59
Q

What gram stain status are enterococci?

A

Positive

“Enter-o-coccus” = like letting someone in, positive thing to do

60
Q

Is haemophilus gram pos or neg?

A

Gram neg

Ha”emo”philus - emo = negative

61
Q

Is listeria gram pos or neg?

A

Positive

Lister = good man = positive

62
Q

name 2 organisms that produce ESBL?

A

e coli

klebsiella pneumoniae

63
Q

what 2 classes of antibiotics inhibit cell wall synthesis

A

beta-lactam antibiotics, glycopeptides

64
Q

what 3 penicillins are broken down by beta-lactamase?

A

penicillin
amoxicillin
piperacillin

65
Q

does ceftriaxone cover psueodmonas?

A

no

66
Q

what type of bacteria is colistin used for? what’s a caution?

A

gram -ve

nephrotoxic and reserved for use against multi-resistant organisms

67
Q

give an example of a diaminopyrimidine

A

trimethoprim

68
Q

What 2 antibiotics classes inhibit cell wall synthesis?

A

beta-lactam antibiotics, glycopeptides

69
Q

What 5 antibiotics classes inhibit protein synthesis?

A 
aminoglycosdies
tetracyclines
macrolides
chloramphenicol 
oxazolidiones
70
Q

give 2 risks of chloramphenicol?

A

aplastic anaemia

grey baby syndrome - can’t metabolise drug

71
Q

what 2 antibiotics classes are inhibitors of DNA synthesis?

A

fluroquinolones

nitroimidazoles

72
Q

what drug class inhibits RNA synthesis?

A

rifamycin

73
Q

what 2 antibiotic classes are cell membrane toxins?

A

daptomycin

colisitin

74
Q

outline the gram staining procedure and results?

A

first step in gram staining is the use of crystal violet dye for the slide’s initial staining.
next step, also known as fixing the dye, involves using iodine to form crystal violet- iodine complex to prevent easy removal of dye.
finally, a decolorizer, often solvent of ethanol and acetone, is used to remove the dye.
If the bacteria stays purple, they are Gram-positive. If the bacteria turns pink or red, they are Gram-negative.

75
Q

give an example of a tetracycline

A

doxycycline

76
Q

who should not be given tetracylines and why

A

pregnancy women
growing children

deposits in bone and teeth

77
Q

what antibiotic should you give as prophylaxis if someone is bitten?

A

co amoxiclav

78
Q

what drug works best for MRSA

A

vancomycin

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