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* year 3 drug formulary > antibiotics > Flashcards

antibiotics Flashcards

1
Q

penicillin examples:

  • oral penicillin? 1
  • IV penicillin? 1
  • broad-spectrum? 2
  • anti-pseudomonal? 1
  • penicillinase resistant? 1
  • mechanism of action?
A

oral
- phenoxymethylpenicillin

IV
- benxylpenicillin (‘benpen’)

broad-spectrum

  • amoxicillin
  • co-amoxiclav

anti-pseudomonal
- tazocin (piperacillin with tazobactam) - IV only

penicillinase-resistant
- flucloxacillin

inhibit the enzymes responsible for cross-linking in peptidoglycan cell walls
-> lysis

all penicillins have a Beta-lactam ring
- some have extra side chains which confer other properties in addtion

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2
Q

which penicillin would be indicated for:

  • streptococcal infections (incl tonisillitis, pneumonia, endocarditis + SSTI)?
  • severe infections by a broad spectrum of organisms (also in neutropenic patients or high likelihood of resistance
  • 2nd/3rd line for UTIs?
  • Clostridial infections (eg tetanus)?
  • empirical treatment of pneumonia?
  • skin + soft tissue infections?
  • hospital acquired infection or intra-abdominal sepsis?
  • meningococcal infections (eg meningitis, septicaemia)?
  • osteomyelitis + septic arthritis?
  • as part of a combination treatment for H-pylori-associated PUD?
A 
streptococcal infections (incl tonisillitis, pneumonia, endocarditis + SSTI)
- penicillin (phenoxymethylpenicillin or benpen)

severe infections by a broad spectrum of organisms (also in neutropenic patients or high likelihood of resistance
- tazocin (nb IV only)

2nd/3rd line for UTIs
- broad spec (amoxicillin or co-amxiclav

Clostridial infections (eg tetanus)
- penicillin (phenoxymethylpenicillin or benpen)

empirical treatment of pneumonia
- broad spec (amoxicillin or co-amxiclav)

skin + soft tissue infections
- penicillinase-resistant (flucloxacillin)

hospital acquired infection or intra-abdominal sepsis
- broad spec (amoxicillin or co-amxiclav)

meningococcal infections (eg meningitis, septicaemia)
- penicillin (phenoxymethylpenicillin or benpen)

osteomyelitis + septic arthritis
- penicillinase-resistant (flucloxacillin)

as part of a combination treatment for H-pylori-associated PUD
- broad spec (amoxicillin or co-amxiclav)

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3
Q

adverse effects of penicillins:

  • serious + happens in all types? 1
  • mild, common + happens in all types? 1
  • common in broad spectrum? 1
  • rare? 2
A

+ penicillin allergy

  • subacute IgG-mediated rash
  • acute anaphylaxis
  • GI upset (incl nausea + diarrhoea)

broad-spec (esp co-amoxiclav + tazocin)
- Abx-associated colitis (ie C.diff)

  • liver toxicity/cholestatic jaundice (esp fluclox)
  • CNS toxicity, incl convulsions + coma (w high doses or where renal impairment delays excretion)
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4
Q

contraindications for penicillins:

  • absolute, for all?
  • relative, for all?
  • relative, for broad spec?
  • absolute, for fluclox?
A

+ pencillin allergy

  • renal impairment (need dose reduction)
  • at risk of C.diff (in hosp + elderly)

+ prior flucloxacillin-related hepatotoxicity

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5
Q

penicillin interactions?

  • common to all?
  • broad spec only?
A
  • methotrexate (reduces renal excretion, increasing likelihood of toxicity)

broad spec only:
- warfarin (kills normal GI flora that synthesises vit K, thus affecting INR)

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6
Q

cephalosporins + carbapenems:

  • examples? 3 + 2
  • mechanism of action?
  • indications? 2
A
  • cephradine
  • cefalexain (oral)
  • cefotaxime
  • meropenem
  • ertapenem

B-lactam ring -> interruption of cell-wall crosslinking -> cell lysis (similar to penicillins)
- nb have a broader spectrum of action (+ more resistant to pencillinases)

nb carbopenems have similar mechanism

1) oral cephalosporins are 2nd + 3rd line for urinary + resp tract infections
2) IV cephalosporins + carbapenems reserved for treatment of severe/complicated/Abx-resistant infections (they are very wide-spectrum!)

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7
Q

cephalosporins + carbapenems:

  • examples? 3
  • common side effect?
  • more serious adverse effects? 2
  • effect of overdose/toxicity?
A
  • cephradine
  • cefalexain
  • cefotaxime
  • meropenem
  • ertapenem
  • GI upset (eg nausea + diarrhoea)

+ c. diff infection
+ allergic/anaphylactic reaction

+ CNS toxicity, incl seizures (if prescribed in high dose or excretion reduced by renal impairment) - esp carbapenems

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8
Q

cephalosporins + carbopenems:

  • examples? 3 + 2
  • relative contraindications for both? 2
  • absolute contraindication for both? 1
  • relative contraindication for carbapenems? 1
A
  • cephradine
  • cefalexain
  • cefotaxime
  • meropenem
  • ertapenem
  • high risk of c.diff infection
  • renal impairment (reduce dose)

+ allergic/anaphylactic reaction

  • epilepsy
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9
Q

cephalosporins + carbopenems:

  • examples? 3 + 2
  • interaction for both?
  • interaction for cephalosporins?
  • interaction for carbapenems?
A
  • cephradine
  • cefalexain
  • cefotaxime
  • meropenem
  • ertapenem

both:
- warfarin (kills norm GI flora, which produces vit K)

cephs:
- aminoglycosides (may increase risk of nephrotoxicity)

carbs:
- valproate (reduce plasma conc + efficacy of valproate)

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10
Q

trimethoprim:

  • examples? 2
  • mechanism of action?
  • indications? 2
A
  • trimethoprim
  • co-trimoxazole (trimethoprim + sulfamethoxazole - nb this is an Abx, not an anti-fungal)

both trimethoprim + sulfamethoxazole inhibit bacterial folate synthesis (at different points) -> can’t synthesis DNA
= bacteriostatic (nb bacteriocidal if taken together)

1) 1st line for uncomplicated UTIs (can also use nitrofuratoin or amoxicillin)
2) co-trimoxazole is used for treatment + prevention of pneumocystis pneumonia in immunosuppressed patients (eg HIV)

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11
Q

trimethoprim:

  • examples? 2
  • common side effects? 2
  • rare, but serious, side effects? 2
A
  • trimethoprim
  • co-trimoxazole (trimethoprim + sulfamethoxazole)
  • GI upset (nausea, vomiting + sore mouth)
  • skin rash (nb rarely can cause anaphylaxis but not often)

+ haematological disorders (eg megaloblastic anaemia, leucopenia, thrombocytopenia)
+ hyperkalaemia (+ elevation of plasma createnine)

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12
Q

trimethoprim:

  • examples? 2
  • absolute contraindication?
  • relative contraindications? 5
A
  • trimethoprim
  • co-trimoxazole (trimethoprim + sulfamethoxazole)

+ first trimester of pregnancy (folate antagonist -> neural tube defects etc)

  • folate deficiency (more susceptible to haem defects)
  • renal impairment (reduce dose)
  • neonates
  • elderly
  • HIV infection
    (all more susceptible to side-effects)
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13
Q

trimethoprim:

  • examples? 2
  • interactions? 3
A
  • trimethoprim
  • co-trimoxazole (trimethoprim + sulfamethoxazole)

potassium-elevating drugs (aldosterone antagonists, ACEi, ARBs)
- predisposes to hyperkalaemia

folate antagonists (eg methotrexate) or drugs that increase folate metabolism (eg phenytoin)
- increases risk of haem adverse effects

warfarin
- enhances anti-coagulant effect (by killing bacteria that synthesise vit K)

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14
Q

nitrofurantoin:

  • mechanism of action?
  • indication?
A
  • drug is metabolised in bacterial cells
  • active metabolite damages bacterial DNA -> cell death

1) uncomplicated lower UTI

nb particularly effective as high conc in urine + most bacteriocidal in acidic conditions (eg urine)

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15
Q

nitrofurantoin:

  • common mild side effects? 2
  • potentially serious side effect?
  • rare side effects (esp w prolonged use)? 3
  • side effect seen in neonates? 1
A
  • GI upset (incl nausea + diarrhoea)
  • URINE CHANGING COLOUR TO BROWN (harmless!!)
  • immediate or delayed hypersensitivity reaction
  • chronic pulmonary reactions (incl pneumonitis + fibrosis)
  • hepatitis
  • peripheral neuropathy
  • haemolytic anaemia (in neonates)
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16
Q

nitrofurantoin:

  • absolute contraindications? 3
  • relative contraindication? 1
  • interactions?
A

+ pregnant women towards term
+ babies in first 3 months of life
+ renal impairment (increases toxicity + doesn’t get to bladder, where needed)

  • long-term prevention of UTIs (as prolonged use increases risk of weird side effects)
  • no significant interactions!
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17
Q

nitrofurantoin:

  • when to take?
  • what to warn patients about?
  • what symptoms should patients looks out for? 2
A
  • take w food to reduce GI effects
  • change in urine colour (harmless + will go back to normal when stop)
  • any unexplained effects (eg SOB or pins + needles)
  • any signs of allergy (as w any Abx)
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18
Q

tetracyclines:

  • examples?
  • mechanism of action?
  • common mechanism of resistance?
A
  • doxycycline
  • lymecycline

inhibit bacterial protein synthesis
- bacteriostatic

nb relatively broad=spectrum but a lot of things are resistant
- common method is via an efflux pump!

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19
Q

tetracyclines:

  • examples? 2
  • indications? 4
A
  • doxycycline
  • lymecycline

1) acne vulgaris (esp when bad)
2) LRTIs (incl infect exacerbations of COPD, pneumonia + atypical pneumonia)
3) chlamydia infection (incl PID)
4) other infections (eg typhoid, anthrax, malaria + lyme disease)

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20
Q

tetracyclines:

  • examples? 2
  • side effects common to most Abxs? 2
  • side effects specific to tetracyclines? 4
A
  • doxycycline
  • lymecycline
  • GI upset (nb v low risk for c.diff though)
  • hypersensitivity reactions (rare)
  • oesophageal irritation, ulceration + dysphagia
  • photosensitivity
  • discolouration +/or hypoplasia of tooth enamel (if given to kids)
  • intracranial HTN (very rare!)
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21
Q

tetracyclines:

  • examples? 2
  • absolute contraindications? 3
  • relative contraindication?
A
  • doxycycline
  • lymecycline

+ pregnancy
+ breastfeeding
+ children under 12
(dt damage to teeth + bones during development)

  • renal impairment
22
Q

tetracyclines:

  • examples? 2
  • relative interactions? 2
A
  • doxycycline
  • lymecycline
  • calcium/antacids/iron (reduce absorption of Abx)
  • warfarin (increase anti-coagulant effect by killing bacteria which produce vit k)
23
Q

tetracyclines:

  • how to take? 2
  • what to look out for? 1
A

swallow whole w plenty of water, while sittingor standing
- to prevent oesophageal irritation

  • take with food, but not dairy (as Ca reduces absorption)
  • allergic reactions
24
Q

aminoglycosides:

  • main example?
  • mechanism of action?
  • which bacteria are naturally resistant? 2
A
  • gentamicin (IV only)

bind irreversibly to bacterial ribosomes + inhibit protein synthesis
- bacteriocidal

(nb think another mechanism as well but not fully understood)

aminoglycosides enter bacteria via an O2-dependent transport system, this system is not found in:
- anaerobic bacteria
- streptococci
(therefore gentamicin is not effective against them)

25
Q

aminoglycosides:

  • main example?
  • important adverse effects? 2
  • interactions which increase risk of these adverse effects?
A
  • gentamicin

nephrotoxicity

  • ciclosporin
  • platinum chemo
  • cephalosporins
  • vancomycin

ototoxicity

  • loop diuretics (eg furosemide)
  • vancomycin

nb ototoxicity is often not noticied until well again and may be irreversible

26
Q

aminoglycosides:

  • main example?
  • relative contraindications? 4
A
  • gentamicin (IV only)
  • renal impairment
  • neonates
  • elderly
    (most likely to suffer renal damage)
  • myasthenia gravis (can impair NMJ transmission, so avoid if poss)
27
Q

aminoglycosides:

  • main example?
  • monitoring required? 2
  • what should patients look out for?
A
  • gentamicin
  • renal function (before + during)
  • plasma drug conc (to work out when to give next infusion)

any signs of ototoxicity

  • change in hearing
  • ringing in their ear
  • vertigo/dizziness
28
Q

Which antibiotic classes should you avoid in pregnancy? 6

incl mneumonic

A

MCAT

  • Metronidazole
  • Chloramphenicol
  • Aminoglycosides
  • Tetracyclines (eg doxycycline, causes teeth/bone discolouration)

plus common ones for UTIs
- nitrofurantoin
- trimethoprim
^use a cephalosporin instead

29
Q

macrolides:

  • examples? 3
  • mechanism of action?
A
  • azithromycin
  • clarithromycin
  • erythromycin

inhibit bacterial protein synthesis
- bind to 50S subunit and block translocation

30
Q

macrolides:

  • examples? 3
  • main indications? 4
A
  • azithromycin
  • clarithromycin
  • erythromycin

1) treatment of respiratory + SSTIs as an alternative to penicillins (if allergic)
2) in severe pneumonia, added to a penicillin to cover atypical organisms (eg legionella + mycoplasma)
3) eradication of h. pylori (eg in PUD) in combination with a PPI + amoxicillin or metronidazole
4) treatment of uncomplicated genital chlamydia or gonorrhoea infection (use azithromycin as best tissue penetration)

31
Q

macrolides:

  • examples? 3
  • commonest side effect?
  • other adverse effects? 2
  • rare adverse effects? 3
A
  • azithromycin
  • clarithromycin
  • erythromycin

GI irritation (especially with ERYthromycin)
- nausea
- vomiting
- abdo pain
- diarrhoea
(can also get thrombophlebitis when taken IV)

  • Abx-associated colitis (c. diff)
  • allergy
  • cholestatic jaundice
  • prolongation of Q-T interval (predisposition to arrhythmias)
  • ototoxicity (at high doses)
32
Q

macrolides:

  • examples? 3
  • absolute contraindication?
  • relative contraindications? 2
A
  • azithromycin
  • erythromycin
  • clarithromycin

+ macrolide hypersensitivity (nb no cross-reactivity with penicillin allergy)

  • severe hepatic impairment
  • severe renal impairment
33
Q

macrolides:

  • examples? 3
  • two groups of drug interactions?
A
  • azithromycin
  • erythromycin
  • clarithromycin

erythromycin + clarithromycin INHIBIT P450 enzymes

  • so increase effect of drugs like warfarin + statins
  • nb azithromycin doesn’t have this effect

other drugs that prolong Q-T interval

  • amiodarone
  • antipsychotics
  • quinine
  • quinolone Abx
  • SSRIs (esp citalopram)
34
Q

macrolides:

  • which one is most commonly prescribed?
  • method of administration?
  • what to warn patients about?
A

clarithromycin

  • azithromycin expensive + not in IV form
  • erythromycin gives most GI side effects
  • oral for all three
  • IV for clari + ery
  • come back if get a rash/allergy
35
Q

quinolones:

  • examples? 3
  • suffix?
  • mechanism of action?
  • which bacteria particularly effective against?
A
  • CIPROfloxacin
  • MOXIfloxacin
  • Levofloxacin

-floxacin

nb technically these are fluroquinolones (pure quinolones aren’t used in clinical practise much)

  • inhibit DNA synthesis
  • most effective against gram negative

nb bacteria rapidly develop resistance to quinolones

36
Q

quinolones:

  • examples? 3
  • indications? 4

incl which specific ones good for each indication

A
  • ciprofloxacin
  • moxifloxacin
  • levofloxacin

generally reserved as 2nd/3rd line as:

  • rapid emergence of resistance
  • association with C diff infections

1) UTI
2) severe GI infection (eg campylobacter, shigella)

3) LRTI
- moxifloxacin or levofloxacin

4) pseudomonas aeruginosa infection
- ciprofloxacin only
- nb this is only oral Abx which works against this organism

37
Q

quinolones:

  • examples? 3
  • side effects common to most Abx? 2
  • specific adverse effects to quinolones? 4
A
  • GI upset
  • allergic reactions (immediate + delayed)
  • neuro stimulant effects (lowering of seizure threshold or hallucinations)
  • inflammation + rupture of muscle tendon (esp Achilles)
  • prolong Q-T interval (+ so increase risk of arrhythmias)
  • c. diff infection
38
Q

quinolones:

  • examples? 3
  • relative contraindications? 3
A
  • ciprofloxacin
  • moxifloxacin
  • levofloxacin

all based on increase susceptibility to side effects

  • with/at risk of seizures
  • people who are growing, ie children (high risk of tendon damage)
  • risk factors for QT prolongation
39
Q

quinolone interactions:

  • examples of quinolones? 3
  • reduce GI absorption of quinolone? 2
  • increase toxicity of other drugs? 1
  • increase risk of seizures? 1
  • increase risk of tendon rupture? 1
  • increase risk of arrhythmias? 5
A
  • ciprofloxacin
  • moxifloxacin
  • levofloxacin

reduce GI absorption of quinolone

  • calcium
  • antacids

ciprofloxacin = p450 INHIBITOR
- increases toxicity of other drugs, esp theophylline (asthma/COPD)

increase risk of seizures
- NSAIDs

increase risk of tendon rupture
- prednisalone

increase risk of arrhythmias

  • amiodarone
  • antipsychotics
  • quinine
  • macrolide Abxs
  • SSRIs
40
Q

metronidazole:

  • which type of antibiotic is it effective against?
  • mechanism of action?
A

anaerobic bacteria (+ protozoa)

  • in anaerobic bacteria, reduction of metronidazole -> free radicals

these bind to DNA -> degradation + cell death

NO effect against aerobic bacteria

41
Q

metronidazole:

- indications? 4

A

treatment of any infection caused by an anaerobe

1) c. diff infection
- gram positive anaerobe

2) oral infections (eg dental abscess) or aspiration pneumonia
- caused by gram negative anaerobes from the mouth

3) surgical + gynae infections
- caused by gram neg anaerobes from the colon (eg bacteroides fragilis)

4) protozoal infections
- incl trichomonal vaginal infections, amoebic dysentery, giardis

42
Q

metronidazole:

  • absolute contraindication? 1
  • relative contraindication? 1
A

+ alcohol consumption!!

  • severe liver disease
43
Q

metronidazole:

- interactions? 3

A

metronidazole is a mild P450 INHIBITOR
- increases effect of statins, warfarin, phenytoin etc

metronidazole is also metabolised by P450, so inducers reduce its antimicrobial efficacy
- eg phenytoin, rifampicin

  • increases toxicity with lithium
44
Q

metronidazole:

  • side effects common to most Abx? 2
  • possible effects when used at high doses for prolonged course? 3
A
  • GI upset
  • allergy

neurological effects

  • peripheral + optic neuropathy
  • seizures
  • encephalopathy
45
Q

metronidazole:

  • what should you warn patietns to avoid while on metronidazole?
  • what are the effects? 4
A

alcohol
- for up to 48 hours after last dose

  • flushing
  • headache
  • nausea
  • vomitting
46
Q

glycopeptides:

  • main example?
  • which bacteria is it effective against?
  • mechanism of action?
A
  • vancomycin
  • gram positive ONLY

inhibits synthesis of cell wall of gram-positive bacteria
- can’t get past lipopolysaccharide part of gram neg bacteria, so doesn’t work

47
Q

glycopeptides:

  • main example?
  • indications? 3
A
  • vancomycin
    1) any infection of MRSA (gram positive, but resistant to penicillins)
    2) gram positive infection which is severe (eg endocarditis) or patient allergic to penicillin

3) treatment of c. diff
- if metronidazole ineffective or poorly tolerated

48
Q

glycopeptides:

  • main example? 1
  • common side effect?
  • specific allergic reaction seen?
  • rare side effects of IV use? 3
A

vancomycin

  • thrombophlebitis (at infusion site)
'red man syndrome'
- anaphylactoid reaction
--- not antigen-mediated (not true allergy) but dt non-specific degranulation of mast cells
- generalised erythema
\+/- hypotension + bronchospasm

nb can also get a true allergic reaction to vancomycin

  • nephrotoxicity (incl renal failure + interstitial nephritis)
  • ototoxicity
  • blood disorders (incl neutropenia + thrombocytopenia)
49
Q

glycopeptides:

  • main example?
  • relative contraindications? 2
  • interactions? 3
A

vancomycin

  • renal failure
  • elderly (increased risk of ototoxicity)

increased risk of ototoxicity + nephrotoxicity with:

  • aminoglycosides (gentamicin)
  • loop diuretics
  • ciclosporin (an immunosuppressant drug)
50
Q

glycopeptides:
- method of administration for different indications?
- what side effects should patients look out for?
monitoring required? 3

A
  • oral for c. diff
  • IV for everything else (as poorly absorbed through lipid membranes)

nb give slow infusion to avoid ‘red man syndrome’

  • tinnitus or hearing loss (reversible if caught early)
  • plasma vancomycin levels
  • U+Es (check for renal impairment)
  • FBCs (check for blood disorders)

* year 3 drug formulary (9 decks)

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