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Finals Pharmacology old > t100 Antibiotics > Flashcards

t100 Antibiotics Flashcards

1
Q

name an aminoglycoside

A

gentamicin

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2
Q

indications aminoglycosides

A

1) severe sepsis, inc where unidentified
2) pyleonephritis and complicated uti
3) biliary and intraabdo sepsis
4) endocarditis

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3
Q

spectrum of action aminoglycosides

A

gram negative aerobes
staphylococci
mycobacteria

Does NOT cover
streptococci
anaerobic bacteria

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4
Q

mechanism of action aminoglycosides

A

Inhibit protein synthesis 30S

bind irreversibly to bacterial ribosome(30S subunit) and inhibit protein synthesis.

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5
Q

when might aminoglycosides need to be combined with something else? what else?

A

combine with penicillin and/or metronidazole when organism unknown

(to cover streptococci and anaerobes)

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6
Q

most important adverse effects aminoglycosides?

A

nephrotoxicity and ototoxicity

aminoglycosides accumulate in tubular epithelial cells and cochlear and vestibular cells where they trigger apoptosis and cell death

nephrotoxicity = reduced urine output, rising serum creatinine and is potentially reversible

ototoxicty = hearing loss, tinnitus (cochlear damage) vertigo (vestibular damage) after infection, may be irreversible

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7
Q

routes of administration aminoglycosides

A

only IV

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8
Q

How to reduce the risk of adverse effects aminoglycosides? contraindications?

A

Administartion:
- diluted and infuses slowly over 30 mins to prevent high concs which can damage the ear

Patient:
-neonates, elderly, renal impaired most at risk - calculate dose correctly and monitor serum closely
- myasthenia gravis avoid unless absolutely neccessary (impairs neuromuscualr transmission

Interactons:
- ototoxicity more likely if coprescribed wirh loop diuretics or vancomycin
- nephrotoxicity more likely if co-prescribed with ciclosporin, platinum chemo, cephalosporins and vancomycin

Monitoring:
- renally excreted, monitor plasma drug concentartions with dose adjustment to prevent complications

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9
Q

name 2 cephalosporins and 1 carbepenem

A
  • cefalexin
  • cefotaxime
  • meropenem
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10
Q

indications cephalosporins and carbepenems?

A
  • oral cephalosporins are 2nd/3rd line option for urinary and respiratory tract infections
  • IV cephalosporins and carbepenems are reserved for infections that are very severe or complicated or caused by resistant organisms
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11
Q

spectrum of action cephalosporins and carbapenems

A

broad spectrum
gram +/-

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12
Q

MoA cephalosporins and carbapenems?

A

B-lactam ring
Inhibit cell wall synthesis

inhibit enzymes responsible for cross linking petidoglycans in bacterial cell walls –> weakens cellw all –> cant maintain osmotic gradient –> bacterial swelling, lysis, death

more resistant ro b-lactamases than penicillins due to fusion of b-lactam ring with dihydrothiazine ring or uniqe side chain

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13
Q

adverse effects cephalosporins and cabapenems?

A

common: GI upset N&V

uncommon: c.diff

hypersensitivity including immediate and delayed reactions may occur (CARBAPENEMS - CAUTION IN PEN-ALLERGIC PATIENTS) cephalosporins are fine in pen allergy

CNS toxicity inc seizures with carbapenems (reduces seizure threshold) esp patients taking high dose or pts with renal impairment

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14
Q

routes of administration cephalosporins and carbepenems?

A

cephalosporins oral (eg cefalexin), tablets, capsulesm oral suspensipn OR injection IV, bolus, infusion or IM

carbapenems only IV injection or infusion

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15
Q

How to reduce risk of adverse effects cephalosporins and carbapenems?

A

Patient:
- CHECK NOT ALLERGIC TO OTHER B-LACTAM ABX
- use with caution in pts at risk of c,diff
- use caution in epilepsy
- dose reduction in renal impairment

Interactions:
- enhances anticoagulant effect of warfarin (INR increases)
- increase nephrotoxicuty of aminoglycosides
- reduces plasma conc and efficacy of valproate

Monitoring:
- symptoms and inflammatory markers

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16
Q

Name 3 macrolides

A

clarithromycin
azithromycin
erythromycin

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17
Q

indications macrolides

A
  • resp and soft tissue as an alternative to penicilin when this is contraindicated by allergy
  • in severe pneumonia added to a penicillin to cover atypical organisms
  • eradication of h.pylori (with amox/metro and PPI)
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18
Q

spectrum of action macrolides

A

broad spectrum
better for gram +
atypical

synthetic eg clarith and azith have increased acitivity against gram negative comapred to eryth

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19
Q

MoA macrolides

A

Inhibit protein synthesis (50S)

bind to 50S ribosome subunit

inhibit bacterial protein synthesis and blocks translocation ‘bacteriostatic’ - stops bacterial growth - assist immune system in removing them

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20
Q

adverse effects macrolides?

A

adverse effects most common and severe with erythromycin

  • irritant : N&V, abdo pain, diarrhoea
  • thrombophlebitis when given IV
  • allergy (but not related at all to penicillins)
  • antibiotic-associated colitis
  • liver abnormalities inc choleststic jaundice
  • prolongation of QT interval
  • ototoxicity in high doses = tinnitus
  • E and C inhibit cytochrome P450 therefore increases plasma conc of drugs such as warfarin and statins .
  • prescribe with caution in patients taking drugs that prolong the QT interval or cause arryth such as amiadarone, antipsychitics, quinine, quinolone abx, SSRIs
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21
Q

metabolism of macrolides

A

mostly hepatic with some renal contribution

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22
Q

how to reduce adverse effects macrolides

A

patient:
- dont prescribe if history of hypersensitivity
- caution in hepatic impairment
- dose reduction in severe renal impairment

Interactions:
- E and C inhibit cytochrome P450 therefore increases plasma conc of drugs such as warfarin and statins .
- prescribe with caution in patients taking drugs that prolong the QT interval or cause arryth such as amiadarone, antipsychitics, quinine, quinolone abx, SSRIs

Monitoring:
- symptoms, examination, inflammatory markers

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23
Q

routes of administration macrolides

A

oral or IV infusion

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24
Q

most commonly prescribed macrolide, why?

A

clarithromycin

fewer SE than erythromycin
cheaper than azithromycin

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25
Q

name 1 nitroimidazole abx

A

metronidazole

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26
Q

Indications metronidazole

A
  • antibiotic associated colitis caused by c.diff
  • oral infections (such as dental abscess) or aspiration pneumonia caused by gram negative anaerobes from the mouth
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27
Q

spectrum of action metronidazole

A

anaerobic bacteria
protozoa eg trichomonas, amoebic dystentry, giardia

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28
Q

MoA metronidazole

A

inhibit protein synthesis

by disrupting the DNA of the susceptible bacteria and inhibiting the protein synthesis of the cell wall leading to cell death;

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29
Q

adverse effects metronidazole?

A

Drug:
- GI upset
- immediate and delayed hypersensitivity
- if prolonged: peripheral and optic neuropathy, encephalopathy, seizures

Patient:
- dose reduce in liver disease

Interactions:
- inhibits acetylaldehyde dehydrogenase which clears alcohol metabolite so cannot drink on metro - will cause disulfiram-like reaction
- inhibits p450 so reduces metabolism of drugs such as warfarin and phenytoin
- p450 enzyme inducers such as phenytoin and rifampicin can reduce plasma conc of metro and reduce antimicrobial efficacy

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30
Q

routes of administartion metronidazole

A

oral
IV
rectal
topical gel

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31
Q

name 1 nitrofuran antibiotic

A

nitrofurantoin

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32
Q

indications nitrofurantoin

A
  • first line antibiotic fro uncomplicated lower urinary tract infections
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33
Q

spectrum of coverage nitrofurantoin

A

works against the gram negative (e.coli) and gram positive (staphlococcus sapriphyticus) organisms that commonly cuase UTI

klebisella has intrinsic resistance to nitrofurantoin

34
Q

adverse effects nitrofurantoin

A
  • GI upset
  • immediate and delayed hypersensitivity
  • yellow/brown urine
  • inflammation and fibrosis of lung
  • hepatitis
  • peripheral neuripathy
  • haemolytic anaemia in neonates
  • haemolytic anaemia in neonates if given towards term to pregnant mother
35
Q

how to reduce adverse effects of nitrofurantoin

A

Contraindications
- pregnant women towards tern
- babies <3 mo
- renal impairment

  • caution for long term prevention of UTI as increases risk of adverse effects
  • take with food/milk to reduce GI upset
36
Q

name 2 basic penicillins

A

benzylpenicillin
phenoxymethylpneicilllin (pen v)

37
Q

indications basic penicillins

A
  1. strep infection including tonsilitis, pneumonia, endocarditis, skina dn soft tissue (added to fluclox if severe)
  2. clostridial infection eg tetanus
  3. meningococcal infection eg meningitis, spetacaemia
38
Q

spectrum of coverage basic penicillins

A

broad spectrum but resistance can develop easily

39
Q

adverse effects all penicillins

A

general
- allergy causing skin rash (subacute IgG delayed)
- allergy causing anaphylaxis (acute IgE)

patient
- CNS toxicity in renal impairment - dose reduction
- reduces renal excretion of methotrexate

40
Q

routes of administartion basic penicillin

A

benzylpenicillin - IV or IM
pen V oral or oral solution

41
Q

what abx is a penicillin that is antipseudomonal

A

piperacillin with tazobactam (tazocin)

42
Q

MoA penicillins

A

inhibit cell wall synthesis

B lactam

43
Q

Indications antipseudonomal penicillins

A

severe infections where there is ?broad spectrum poetntial pathogens and antibiotic resistance is likley eg hospital acquired, immunocompromise

  1. LRTI
  2. UTI
  3. Intra-abdo sepsis
  4. skin and soft tissue
44
Q

what is tazobactam, how does it work

A

B lactamase inhibitor

gives activity against b-lactamase producing bacteria eg staph aureus, gram negative anaerobes

45
Q

what is piperacillin, how does it work

A

penicillin with side chain urea to give activity against pseudonomas aerginosa

46
Q

route of administartion tazocin

A

IV

47
Q

name 2 broad spectrum abx

A

amoxicillin
co-amoxiclav

48
Q

indications for broad spectrum abx

A
  1. pneumonia
  2. UTI
  3. co-amoxiclav for hospital-aquired infection or intra-abdo sepsis which may be caused by gram negative and anaerobic and antibiotic resistant organisms
  4. as part of h.pylori treatment
49
Q

why is amoxicillin considered broad spectrum

A

side chain amino group gives activity against aerobic gram negative bacteria

50
Q

what is clauvinic acid?

A

added to amoxicillin to create co-amoxiclav

b-lactamase inhibitor - increases avitivity to staph aureus and gram neagtive anaerobes

51
Q

routes of administartion broad spectrum penicillins

A

oral and IV

52
Q

name penicillinase resistant penicillin

A

flucloxacilin

53
Q

indications flucloxacillin

A
  1. skin and soft tissue such as cellulitis
  2. osteomyelitis and septic arthritis
  3. other infections such as endocarditis
54
Q

action of flucloxacillin

A

normal penicllin but side chain means effective against b lactamase producing staphlococci

55
Q

how is MRSA resistant?

A

reduces penicillin binding affinity

56
Q

what is MRSA

A

MRSA refers to staphylococcus aureus bacteria that have become resistant to beta-lactam antibiotics such as penicillins, cephalosporins and carbapenems.

57
Q

how is MRSA treated

A

Eradication usually involves a combination of chlorhexidine body washes and antibacterial nasal creams.
Antibiotic treatment options for MRSA are:
Doxycycline
Clindamycin
Vancomycin
Teicoplanin
Linezolid

58
Q

what are extended spectrum beta lactamase bacteria?

A

ESBLs are bacteria that have developed resistance to beta-lactam antibiotics.

They produce beta lactamase enzymes that destroy the beta-lactam ring on the antibiotic. They can be resistant to a very broad range of antibiotics.

ESBLs tend to be e. coli or klebsiella and typically cause urinary tract infections but can also cause other infections such as pneumonia.

They are usually sensitive to carbapenems such as meropenem or imipenem.

59
Q

Name 3 quinolones

A

Ciprofloxacin, moxifloxacin, levofloxacin

60
Q

Indications quinolones

A

reserved as 2nd or 3rd line treatment due to
- rapid emergency of resistance
- association with c.diff

used in:
- uti
- severe gi
- LRTI
- ciprofloxaxin is only oral in use witha ction against pseudomonas aerginosa

61
Q

MoA quinolones

A

inhibit DNA synthesis

62
Q

Spectrum of action quinolones

A

Good at aerobic gram negative therefore good at uti and gi

mox and levo are newer and have enhanced action against gram positive so good for LRTI which can be positive or negative gram

63
Q

adverse effects quinolones

A
  • GI upset
  • immediate and delayed hypersensitivity

Class specific
- neuro defecit (lower seizure threshold and hallucinations)
- inflammtion and rupture of muscle tendons
- prolong QT therefore increase arrythrmias
- promote c.diff, specfically hypervirulent 027 strain

Caution - patient
- ppl w seizures or at risk
- ppl growing (risk of arthropathy)
- risk factors for prolonged QT eg cardiac disease or elecgtrolyte disturbance or drugs

Interactions:
- calcium and antacids reduce absorption
- ciprofloxacin inhibits some cytochrome p450 increasing toxicity risk of some drugs specifically theophylline
- co-pres w NSAIDs increase risk of seizures
- co-pres w steroids increase risk of tendon rupture

64
Q

routes of administartion quinilones

A

oral/IV

65
Q

name two tetracyclines

A

doxycycline
lymecycline

66
Q

indications tetracyclines

A

acne vulgaris
LRTI inc infective exacerbations of COPD (haemophilus influenzae), pneumonia and atypical pneumonia
Chlamydia infection adn PID
typhoid,anthrax, malaria, lyme disease

67
Q

MoA tetracyclines

A

inhibit protein synthesis 30S ribosome subunit

(bacteriostatic)

68
Q

important adverse effects

A
  • GI upset
  • hypersensitivity

specific to tetracycylines
- oesophageal irritaton, ulcerationa dn dysphagia
- photosensitivity
- discolouration and hypoplasia of tooth enamel in children
intracracial hypertension

Contrainications
- pregnancy and breastfeeding
- children less than 12
- renal impaitment

69
Q

routes of administartion tetracyclines

A

oral

70
Q

sulfonamide antibiotics?

A

trimethorprim
co-trimoaxole

(sulfasalazine)

71
Q

indications sulfonamide antibiotics

A
  • trimethoprim 1st line for uncomplicated uti (w nitro and amox)
  • co-trimoaxole is used for treatment and prevention of pneumocystitis pneumonia in ppl with immunosuppression eg due to HIV infection
72
Q

MoA sulfonamide abx

A

inhibit folate synthesis

73
Q

spectrum of action sulfonamides

A

gram positive and negative but lots of resistance

74
Q

adverse effects sulfonamides?

A

trimethoprim
- GI upset
- skin rash
- hypersensitivity

patient
- use cautiously in folate deficiency
- dose reduction in renal impairment

75
Q

routes of administration sulfonamides

A

trimethoprim - only oral

co-trimoxazole - oral or IV

76
Q

indications vancomycin

A
  • treatment of gram positive infection eg endocarditis, where infection is seveere and/or penicillins cannot be used due to resistance eg MRSA
  • treatment of abx-associated colitis cuased by c.diff. usually second line after metronidazole
77
Q

MoA vancomycin

A

inhibit cell wall synthesis

78
Q

spectrum of action vancomycin

A

gram positive

79
Q

adverse effects vancomycin

A

most common
- thrombophlebitis at infusion site
- ‘red man syndrome’ if infused too quickly (generalised erythema, hypotension, bronchospasm)

  • nephrotoxic and ototoxic and can cause blood disorders eg neutropenia, thrombocytopaenia
    (risk increases with co-prescription of aminoglycosides, loop diuretics or ciclosporin)
80
Q

Prevention of adverse effects vancomycin

A
  • infuse slowly
  • monitor plasma drug conc
81
Q

routes of administartion vancomycin

A

IV or oral

IV for endocarditis

oral for c.diff

Finals Pharmacology old (5 decks)

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