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pharmacology > antimicrobials > Flashcards

antimicrobials Flashcards

1
Q

What are the MINDME guidelines for antimicrobial therapy?

A

M: microbiology guidelines used whenever possible
I: indications should be evidence based
N: narrowest spectrum required
D: dosage appropriate to the site and type of infection
M: minimise duration of therapy
E: ensure mono therapy in most situations

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2
Q

What is directed therapy vs. empirical therapy?

A

directed therapy - base choice of therapy on culture or susceptibility test results
empirical therapy - known common pathogens and resistance patterns (seasonality)
duration should be as short as possible, should not exceed 7 days unless there is proof this length of time is inadequate

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3
Q

Targets of antibacterials?

A

cell wall synthesis
protein synthesis
DNA- inhibit cell division
other metabolic processes

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4
Q

Factors affecting choice of antibacterial

A

bacterial factors: what type of organism, how resistant
host factors: site of infection, allergies, renal/hepatic function, concomitant drugs, age
drug factors: spectrum of activity, pharmacokinetics, adverse effects profile, cost

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5
Q

Antibacterial families targeting cell wall bio synthesis

A

beta-lactams, glycopeptides, cephalosporins

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6
Q

Antibacterial families targeting protein biosynthesis

A

macrolides, tetracyclines, aminoglycosides, oxazolidinones

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7
Q

Antibacterial family targeting DNA replication and repair

A

Fluoroquinolones

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8
Q

antibacterial families targeting folate synthesis?

A

trimethoprim, sulfonamides

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9
Q

antibacterial family targeting cell membrane?

A

daptomycin

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10
Q

antibacterial families targeting protein synthesis?

A

linezolid, tetracyclines, macrolides, aminoglycosides

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11
Q

size of virus particles

A

size range 10-400nm in diameter, most need to be viewed with EM
bacteriophage: 225nm

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12
Q

Can visions exist extracellularly?

A

Yes, rotavirus exists extracellularly for a few hours in the air

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13
Q

What is a nucleocapsid?

A

composed of DNA or RNA or a capsid, some viruses may also have an envelope

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14
Q

structural elements of a virus?

A
  1. nucleic acid: DNA or RNA, genome can be segmented or circular
  2. capsid: capsomeres
  3. envelopes
  4. spikes
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15
Q

what is the ending for virus order, family, subfamily and genus

A

O: virales
F: viridae
subfamily: virinae
G: virus

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16
Q

what are the two main systems for classifying viruses

A

ICTV: international committee on taxonomy of viruses
- main body
Baltimore system complements ICTV, focusses on viral genome and the methods used to synthesise mRNA

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17
Q

How would you classify viruses based on the genome? (5)

A

dsDNA, ssDNA, dsRNA, ssRNA

  • in ssRNA, + strand RNA is identical to mRNA sequence produced by the virus (positive strand)
  • strand RNA is complementary to mRNA sequence (negative strand)
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18
Q

common target of antiviral drugs? problems that can occur?

A

viral polymerase; toxicity can arise when viral polymerase is similar to host cell polymerase
most agents are virustatic - often by the time a viral infection is diagnosed, the virus spread and replication is complete

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19
Q

What does aciclovir target?

A

viral DNA/RNA synthesis

20
Q

What does zidovudine target?

A

viral DNA/RNA synthesis

21
Q

What do interferons target?

A

viral protein synthesis

22
Q

Mechanism of acyclovir?

A

(prodrug, activated by viral kinases)

= chain terminating agent; added to chain by viral polymerase but lacks 3’OH required for chain extension

23
Q

Mechanism of zidovudine?

A

(prodrug, activated by viral kinases)
= NRTI (nucleoside reverse transcriptase inhibitor)
= chain terminator, inhibits viral reverse transcriptase
- has some toxicity: bone marrow suppression, nausea, vomiting, malaise
- resistance is well recognised
- combination/alternating therapy slows development of resistance and minimised toxicity to a particular tissue

24
Q

ways to monitor antiviral therapy

A
  • measure viral load e.g. by real time PCR

- monitoring mutation rates e.g. by RFLP (restriction fragment length polymorphism) and sequencing

25
Q

mechanism of ritonovir?

A

protease inhibitor
prevent processing of viral polyproteins, inhibit viral maturation
used in combination with NRTIs

26
Q

mechanism of oseltamivir

A
  • competitive, reversible inhibitors of neuraminidase
  • active against influenza A and B
  • resistance minimal to date
  • reduce viral shedding and disease duration if given early
27
Q

what disease is ritonavir used to treat?

A

HIV

28
Q

types of drugs used to treat HIV?

A

non-NRTIs and protease inhibitors

29
Q

types of drugs to treat influenza?

A

ion channel blockers and neuraminidase inhibitors

30
Q

types of drugs used to treat HBV?

A

NRTIs and NNRTIs

31
Q

drug used to treat HCV?

A

ribavirin
interferon, half-life can be extended by PEG-ylation; used in combination with ribavirin with effectiveness depending on HCV genotype

32
Q

side effects of interferon used to treat hepatitis?

A

flu-like symptoms: fever, myalgia, headache

33
Q

What is amphotericin - B used to treat?

A
  • candidiasis = systemic mycoses (fungal infections)
  • caused most frequently by candida albicans (causing cutaneous lesions of nails and skin, mucosal lesions of mouth and vagina, systemic lesions of immunocompromised patients)
  • used for superficial and systemic fungal infections
  • severe side effects: damage to kidney and blood forming tissues, cardiac arrest
34
Q

Targets for antifungals?

A
  • azoles: inhibit enzyme for sterol synthesis (inhibit fungal cell membrane biosynthesis)
  • polyenes: bind to membranes causing cell leakage and death
  • inhibit nucleic acid synthesis
35
Q

metronidazole may target two types of antimicrobials, which ones?

A

bacteria and protozoa

36
Q

Ivermectin: what microbe is it used to treat, what is its target?

A

nematodes, unique neurotransmitters

37
Q

3 features of Kingdom Protista?

A

most are unicellular
polyphyletic
lack level of tissue organisation present in higher eukaryotes

38
Q

What is Trichomonas vaginalis?

A

= pathogenic trichomonad. Anaerobic, flagellated protozoan parasite
Trichomoniasis is a sexually transmitted infection in humans

39
Q

cause of African sleeping sickness?

A

pathogenic Euglenozoa: trypanosomes
specifically T. brucei gambiense and T. brucei rhodesiense
Tsetse fly is a Trypanosoma vector

40
Q

What does entamoeba histolytica cause?

A

causes amoebic dysentery
3rd leading cause of parasitic death worldwide
acquired by consuming E. histolytica cysts
may migrate to lungs, brain, liver or skin

41
Q

What is the effect of toxic algal blooms?

A
  • brevetoxins produced by dinoflagellates are toxic by inhalation or ingestion
  • oxygen depletion of the water column
42
Q

Example of an apicomplexan?

A

Plasmodium, causing malaria
clonal and sexual stages are haploid except for zygotes
sporozoite is the motile, infective stage

43
Q

Structures making up the apical complex of anti-protozoal

A

polar ring, conoid, subpellicular microtubules, micronemes, rhoptry, micropore

44
Q

4 main human species of plasmodium

A

P. falciparum, vivid, malariae, ovale

45
Q

What mosquito transmits plasmodium?

A

anopheles (~40 species transmit plasmodium)

46
Q

Drugs to treat malaria?

A

quinine - serious side effects
chloroquinone - used in prophylaxis and treatment; P. falciparum resistant and P. vivax is developing resistance
antifolate compounds: mefloquine, widespread resistance
artemisinin

47
Q

What to do in treating eukaryotic or viral infections

A
  • usually have some toxicity to host cells
  • careful monitoring required in systemic administration e.g. liver function tests
  • topical application is preferred

pharmacology (17 decks)

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