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Sykes > Section 2 > Flashcards

Section 2 Flashcards

1
Q

How do the mechanisms of action of bactericidal and bacteriostatic medication differ?

A

Bactericidal - interfere with cell wall/nucleic acid synthesis
Bacteriostatic - inhibit protein synthesis

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2
Q

What are the concentration-dependent antibiotic groups?

A

Fluoroquinolones and aminoglycosides

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3
Q

Which antibiotics are lipid soluble?

A

Rifampin, fluoroquinolones, TMPS, chloramphenicol

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4
Q

Which antibiotics are excreted in active form through the liver and concentrated in bile?

A

Doxycycline and ampicillin

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5
Q

Give examples (2) of bacteria with innate resistance to antibiotics

A

Enterococci and cephalosporins - lack binding proteins to bind ABs
Anaerobic bacteria and aminoglycosides - O2 needed for entry into cell

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6
Q

What family of antiviral agent are acyclovir and famcyclovir? What is their MOA?

A

Antiherpesviral - guanosine analogue
Activated by herpesvirus thymidine kinase - phosphorylates
Further phosphorylated by host cell enzymes - concentrate in virus-infected cells and inhibit DNA polymerase
Famcyclovir = prodrug

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7
Q

What side effects are associated with systemic acyclovir?

A

Myelosuppression, renal tubular necrosis, hepatic necrosis (all cats)

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8
Q

How is famcyclovir tolerated in cats?

A

High doses required
Well tolerated

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9
Q

What are Idoxuridine and Trifluridine? What is their MOA/clinical application?

A

Antiherpesviral
Halogenated thymidine analogues
Toxic systemically
Trifuridine - better corneal penetration, expensive, irritating

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10
Q

What is vidarabine?

A

Antiherpesviral
Adenosine analogue

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11
Q

What is lysine?

A

Antiherpesviral
Amino acid - poorly understood mechanism

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12
Q

What is the evidence for lysine use in cats?

A

Shown to be effective in treating and reducing shedding in cats with FHV-1 conjunctivitis
Several studies shown that supplementation does not prevent response signs in shelter cats

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13
Q

What is zidovudine (AZT)? What is it’s MOA?

A

Antiretroviral
Thymidine analogue

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14
Q

What are the side effects of zidovudine (AZT)?

A

Non-regenerative anaemia, neutropenia

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15
Q

What is oseltamivir? What is it’s MOA?

A

Tamiflu - antiinfluenza
Neuraminidase inhibitor - surface glycoprotein of influenza A/B

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16
Q

What is the MOA of beta-lactam ABs?

A

Bind and inhibit penicillin binding proteins - needed for cross-linking peptidoglycan layer of bacterial cell walls. Cell walls constantly remodelled, hydrolases still active. Ends in cell rupture

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17
Q

Which bacteria are more sensitive to beta-lactam ABs?

A

G+ve - have thicker cell walls

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18
Q

What are the mechanisms of B-lactam resistance?

A

B-lactamase
Altered penicillin-binding proteins
G-ve - exclusion of drugs that would diffuse through porins

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19
Q

Are beta-lactams time or concentration dependent? How long is their half life?

A

Time
Short half life

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20
Q

What b-lactam inhibitors are available?

A

Clavulanic acid, sulbactam and tazobactam

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21
Q

How are beta-lactams excreted?
Do they penetrate the BBB?

A

Renal
Poor penetration of BBB

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22
Q

How are cephalosporines excreted?
Do they penetrate the BBB?

A

Renal
Poor penetration of BBB

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23
Q

What family of drug is vancomycin? What is its MOA?

A

Glycopeptide
Inhibits cell wall synthesis

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24
Q

What drugs inhibit nucleic acid?

A

Fluoroquinolones, metronidazole, rifamycin, TMPS

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25
Q

What in the MOA of fluoroquinolones?

A

Bind to DNA gyrase and topoisomerase IV - disrupts bacterial DNA synthesis

26
Q

What affects fluoroquinolones efficacy against G+ve/G-ve bacteria?

A

DNA gyrase - G-ve
Topoisomerase - G+ve

27
Q

Rank fluoroquinolones based on anaerobic activity?

A

Pradofloxacin > Marbofloxacin > Enrofloxacin

28
Q

Which antibiotic(s) are associated with retinal injury in cats? What is the prognosis?

A

Enrofloxacin
Can resolve following withdrawal

29
Q

Which antibiotics are associated with false positive on urine glucose dipsticks?

A

Cephalosporines and fluoroquinolones

30
Q

Metronidazole - cidal or static?

A

Cidal

31
Q

Metronidazole MOA

A

Diffuses into bacterial cells as prodrug, activated in cytoplasm. Generates free radicals and damages DNA

32
Q

What is the mechanism of metronidazole’s immunomodulatory activity?

A

Scavenges ROS
Modulates neutrophil activity

33
Q

What is the main side effect of metronidazole and how is it treated?

A

Neurotoxicity
Diazepam

34
Q

Ri

A
35
Q

Rifamycins - cidal or static?

A

Cidal

36
Q

Rifamycins MOA?

A

Inhibit DNA-dependent RNA polymerase - impaired RNA synthesis

37
Q

Is rifampin lipid soluble?

A

Very - allows high intracellular concentration, can be used to treat intracellular infections (eg mycobacterium/brucella)

38
Q

Rifampin - side effects?

A

Vomiting, anorexia. Red discolouration of body fluids. Hepatopathy

39
Q

TMPS - MOA?

A

Inhibit bacterial folate metabolism - interferes with purine synthesis

40
Q

TMPS - static or cidal?

A

Separately static, together cidal

41
Q

TMPS - spectrum?

A

Broad

42
Q

TMPS - acid or base?

A

Weak base

43
Q

Which antibiotics inhibit protein synthesis?

A

Aminoglycosides, chloramphenicol, tetracyclines

44
Q

Aminoglycosides - MOA

A

Multiple
Bind electrostatic ally to bacterial wall - dispose Ca and Mg (greater in G-ve) - disrupt permeability
Taken up by cell, trapped in cytoplasm
Bind to 30S subunit

45
Q

What type of infection are aminoglcyosides ineffective against?

A

Anaerobic - MOA O2 dependent

46
Q

Aminoglycosides - oral bioavailability?

A

Very poor

47
Q

Aminoglycosides - cidcl or static?

A

Cidal

48
Q

Aminoglycosides - water or lipid soluble?

A

Water

49
Q

Aminoglycosides - time or concentration dependent?

A

Concentration

50
Q

Aminoglycosides - adverse effects?

A

Nephrotoxicity, ototoxicity, neuromuscular blockade

51
Q

Chloramphenicol - MOA

A

Binds to 50S subunit of bacterial ribosome

52
Q

Chloramphenicol - cidal or static?

A

Traditionally thought of as static, recent evidence cidal

53
Q

Chloramphenicol - spectrum

A

Broad

54
Q

Chloramphenicol - lipid/water soluble?

A

Lipid

55
Q

Chloramphenicol side effects

A

Reversible bone marrow suppression

56
Q

List macrolides and lincosamides

A

M - erythromycin, tylosin, clarithromycin, azithromycin
L - clindamycin, lincomycin

57
Q

Macrolides/lincosamides - MOA

A

Bind to 50S subunit

58
Q

Macrolides/lincosamides - cidal or static?

A

Static

59
Q

Tetracyclines - MOA

A

Bind to 30S

60
Q

Tetracyclines - cidal or static?

A

Static

61
Q

Tetracyclines - lipid or water soluble?

A

Lipid

Sykes (2 decks)

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