antibiotic 2 Flashcards

1
Q

what are some examples of aminogylcosides

A

gentamicin

amikacin

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2
Q

MOA for gentamicin

A

bind irreversibly to bacterial ribosomes (30s subunit) - inhibit protein synthesis

bactericidal

enter bacterial cells via O2 dependent transport system (strep and anaerobic does not have this system, so resistance)

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3
Q

what are organisms are gentamicin good for

A

spectrum incl - gram -ve aerobic bacteria, staphylococci and mycobacteria - it depends on O2 dependent mechanism to enter the bacteria cells

strep and anaerobic bacteria does not have this mechanism so resistant

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4
Q

what does gentamicin resistance come into existence

A

reduced cell membrane permeability to aminoglycoside

acquire enzyme which modify aminoglycoside to prevent them reaching to ribosome

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5
Q

indication for gentamicin

A

severe sepsis - incl unknown source

pyelonephritis and complicated UTI

biliary and other intra-abdo sepsis

endocarditis

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6
Q

contra-indication for gentamicin

A

aminoglycosides are excreted in renal

can cause renal, cochlear and vestibular damages especially in elderly and neonates

renal impairment

can impair neuromuscular transmission so should not be given to myasthenia gravis

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7
Q

side effect of gentamicin

A

nephrotoxicity

ototoxicity - tinnitus, vertigo

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8
Q

interaction of gentamicin

A

ototoxicity - with loop diuretics or vancomycin

nephrotoxicity - with ciclosporin (immunosuprresant), platinum chemo, cephalosporins or vancomycin

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9
Q

what are some examples of macrolides

A

clarithromycin
erythromycin
azithromycin

-mycin

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10
Q

MOA for erythromycin

A

binds to 50s subunit of ribosome

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11
Q

which one of the macrolides have the greatest anti-bacterial activity?

A

erythromycin -come from a bacteria and hence nature - has great G+ve but little G-ve affects

Clarithromycin and Azithromycin - are synthetic and so have greater G-ve activity

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12
Q

contra-indication for clarithromycin

A

macrolide hypersensitivity

excepted in the liver - hepatic impairment

dose reduction in renal impairment

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13
Q

side effect of clarithromycin

A

most common and severe with erthromycin

macrolides are irritants - N+V, abdo pain, and diarrhoea

allergy, antibiotic-associated collitis

cholestatic jaundice

prolongation of QT interval

ototoxicity at high dose

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14
Q

indication for clarithromycin

A

respiratory infection

skin and soft tissue infection - alternative for penicillin

severe pneumonia - added to penicillin

eradication of H.pylori (along with metronidazole or amoxicillin)

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15
Q

interaction of erythromycin

A

erythromycin and clarithromycins are p450 cytochrome inhibitors

  • warfarin - inc risk of bleeding
  • statins - inc risk of myopathy

QT intervals prolong drugs - - amiodarone, antipsychotics, quinine, quinolone antibiotics, SSRIs

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16
Q

what are the examples of quinolones

A

ciprofloxacin
moxifloxacin
levofloxacin

  • floxacin
17
Q

MOA of ciprofloxacin

A

inhibiting DNA synthesis

18
Q

what are the ability of quinolones

A

active aginst G-ve organisms - UTI and GI tract infection

moxifloxacin and levofloxacin - newer and active against G+ve - RTI as well

19
Q

indication of quinolones

A
  • UTI
  • severe GI tract infection
  • lower RTI - moxifloxacin and levofloxacin
  • ciprofloxacin - only antibiotics which can be used against pseudomonas aeruginosa
20
Q

contra-indication for quinolones

A

caution in those who might have seizures

those who are growing - potential arthropathy

QT prolongation - cardiac disease or electrolyte disturbance

21
Q

side effect of quinolones

A

GI upset - N+D

immediate and delayed hypersensitivity

neurological effects - lowering seizure threshold

rupture of muscle tendons

prolong QT interval - increase risk of arrhythmia

C.diff colitis

22
Q

interaction of quinolones

A

drugs containning divalent cations eg Ca+, antacidds, reduce absorption and efficacy of quinolones

ciprofloxacin - P450 cyctochrome inhibitors - theophylline

Co-prescription with NSADs - inc seziures with prednisolone - inc risk of tendon rupture

drugs which prolongs the QT intervals - amiodarones, antipsychotics, quinine, macrolide, SSRIs

23
Q

what are some examples of glycopeptide

A

vancomycin

24
Q

MOA of vancomycin

A

inhibits growth and cross-linking of peptidoglycan chains

inhibit synthesis of cell wall of G+ve only and inactive against most G-ve

25
Q

indication for vancomycin

A

G+ve infection - endocarditis (esp in the case of MRSA)

antibiotic associateed colitis - C.Diff (usually 2nd line where metronidazole is ineffective)

26
Q

contra-indication for vancomycin

A

close monitoring for toxicity

renal impairment
elderly - inc risk of hearing impairment

27
Q

side effect of vancomycin

A

pain and thrombophlebitis (vein inflammation)

if infused too quickly - - red man syndrome - erythema and hypoTN and bronchospasm

allergy

nephrotoxic
ototoxicity
blood disorder - neutropenia and thrombocytopenia

28
Q

interactions of vancomycin

A

ototoxicity and nephrotoxicity when with amioglycoside, loop diuretics or ciclosporin (immunosuppresants)

29
Q

what drug class is metronidazole

A

anaerobic antibiotics

30
Q

MOA of metronidazole

A

reduction of metronidazole in anaerobic bacteria - cause DNA degradation and cell death

only anaerobic bacteria can reduce metronidazole so aerobic bacteria is not effective

31
Q

indication for metronidazole

A

antibiotic associated colitis - C.Diff

Oral infection or aspiration pneumonia - G-ve anaerobes from mouth

surgical and gynaecological infection - G-ve anaerobes from the colon

protozoal infection - trichomonal vaginal infection, amoebic dysentery, giardiasis (parasitic infection)

32
Q

contra-indication for metronidazole

A

metabolised by cyctochrome P450

liver impairment

alcohol should not be drunk during the course of metronidazole - metraonidazole inhibit the enzyme required for alcohol metabolism

33
Q

side effect of metronidazole

A

GI upset - N+V

hypersensitivtiy reaction

neurological - peripheral and optic neuropathy, seizures and encephalopathy - if prolonged used

34
Q

interaction of metronidazole

A

some inhibitory effect on cytochrome P450 - warfarin and phenytoin

cytochrome P450 inducers eg rifampicin and phenytoin - result in inc plasma conc

inc risk of toxicity with lithium