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Finals pharmacology new > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

which anti-biotics may cause c.diff? what other drug also increases the risk

A

Receipt of broad spectrum antibiotics* is often the cause and risk is increased with older age, frailty and use of proton pump inhibitors.
The ‘C’ antiobiotics are particularly associated with CDI:
Co-amoxiclav
Clarythromycin
Ciprofloxacin
Clindamycin
Cephalosporins

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2
Q

which are b lactam abx

A

Cephalosporins
Carbapenems
Benzylpenicillin
Penicillin V
Amoxicillin
Co-amoxiclav
Pipercillin and tazobactam
Flucloxacillin

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3
Q

Which abx inhibit protein synthesis?

A

Macrolides 50S
Aminoglycosides 30S
Lincosamides 50S
Tetracyclines 30S

5 points on M = 50S
3 points on A = 30S

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4
Q

Which antibiotics are P450 inducers?

A

Rifampicin
Griseofulvin

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5
Q

which abx are p450 inhibitors?

A

AODEVICES

A
O
D
Erythromycin (Macrolides)
V
Isoniazid
Ciprofloxacin and Chloramphenicol
E
Sulfonamides

+ Metronidazole

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6
Q

What does cell wall size of gram positive vs gram negative tell you about the action of b lactam antibiotics?

A

Gram positive abx have a much thicker cell wall. Gram negative bacteria are more protected by lipids etc added to their thin cell wall. B lactam antibiotics which inhibit cell wall synthesis are therefore more effective against gram positive bacteria

Side chains can be added which make penicillins more effective against gram negative bacteria eg amino group in amoxicillin.

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7
Q

mechanism of resistance MRSA

A

MRSA reduces penicillins binding affinity

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8
Q

what does MRSA mean

A

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

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9
Q

How to treat MRSA?

A

options:

Doxycycline
Clindamycin
Vancomycin
Teicoplanin
Linezolid

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10
Q

what are ESBLs?

A

Extended Spectrum Beta Lactamase bacteria (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.

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11
Q

name aminoglycosides

A

gentamicin, neomycin

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12
Q

what drugs increase risk of nephrotoxicity when co-prescribed aminoglycosides

A

ciclosporin, platinum chemo, cephalosporins and vancomycin

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13
Q

what drugs increase risk of ototoxicty aminoglycosides co-prescribed

A

diuretics, vancomycin

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14
Q

contraindications aminoglycosides

A

by inj: myasthenia gravis.

In ear: patent grommet, perforated tympanic membrane

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15
Q

spectrum of action aminoglycosides

A

gram negative aerobes, staphylococcus and mycobacteria

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16
Q

what drugs should you avoid with meropenem

A

valproate (reduces conc of valproate). Enhances anticoag of warfarin (INR increases),

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17
Q

name oral cephalosporin

A

cefalexin

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18
Q

name macrolides

A

clarithromycin, azithromycin, erythromycin

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19
Q

what macrolide, more likely to get adverse effects?

A

erythromycin

20
Q

adverse effects macrolides

A

Irritant = N&V, abdo pain, diarrhoea, thrombophlebitis when IV.

antibiotic associated colitis and c.diff.

Liver abnormalities including cholestatic jaundice,

prolongation of QT,

ototox in high doses = tinnitus

21
Q

caution macrolides

A

caution in patients taking drugs which prolong QT such as amiadarone, antipsychotics, quinine, quinolone abx, SSRIS.

Cuation in hepatic impairment as hepatic processed.

Caution in renal impairment (dose reduce).

May aggravate myasthenia gravis

22
Q

what kind of bacteria does metronidazole work on

A

anaerobic

23
Q

caution metronidazole

A

metabolised by cytochrome p450 so dose reduce in severe liver disease

24
Q

pt communication metronidazole

A

alcohol- disulfiram like reaction. Don’t drink for the duration of treatment and for 48 horus after.

25
Q

unique adverse effects nitrofurantoin

A

can turn urine dark yellow/brown.

chronic pulmonary reactions (including pneumonitis and fibrosis), hepatitis and peripheral neuropathy.

In neonates can cause haemolytic anaemia

26
Q

contraindications nitrofurantoin

A

pregnant women near term,
babies under 3 months.

Contraindicated in renal impairment as it increases toxicity and reduces efficacy due to lower urinary drug concs.

27
Q

what drug do penicillins reduce the renal excretion of and therefore increase risk of toxicity

A

reduces renal excretion of methotrexate, increasing risk of toxicity

28
Q

what does using tazocin increase activity for

A

psedomonas

29
Q

what adverse effects/interactions do you get specifically with broad spectrum penicillins

A
  1. risk of c.diff
  2. increases anticoag of warfarin as kills vit k producing flora
30
Q

unique adverse effect fluclox

A

liver toxicity including cholestasis and hepatitis

31
Q

name quinolones

A

ciprofloxacin, moxifloxacin, levofloxacin

32
Q

what is the only oral abx with action against pseudomonas aerginosa

A

ciprofloxacin

33
Q

unique adverse effects quinolones

A

lowering seizure threshold, hallucinations, inflammation and rupture of muscle tendons. Quinolones (particularly moxifloxacin) prolong the QT interval and therefore increase risk of arrhythmias.

34
Q

caution in who - quinolones

A

ppl at risk of seizures, who are growing (risk of arthropathy) and risk factors for QT prolongation

35
Q

co-prescription with what increases risk of tendon rupture quinolones

A

prednisolone

prescribe olone, not together!

36
Q

co-prescription with what increases risk of seizures quinolones

A

NSAIDs

37
Q

ciprofloxacin is a p450 ? impact?

A

Ciprofloxacin inhibits certain P450 enzymes increasing risk of toxicity with some drugs, notably theophylline

38
Q

unique adverse effects tetracyclines

A

Oesophageal irritation, ulceration and dysphagia, photosensitivity, discoloration and/or hypoplasia of tooth enamel if prescribed for children. Intracranial hypertension is a rare adverse effect

39
Q

contraindications tetracyclines

A

tetracyclines bind to teeth and bones during fetal development infants and childhood so

DO NOT prescribe during pregnancy, breastfeeding or for children under 12. Avoid in ppl with renal impairment

40
Q

unique adverse effects anti-folates

A

haematological disorders such as megaloblastic anaemia, leukopenia and thrombocytopenia due to inhibition of folate synthesis.

Can cause hyperkalemia

41
Q

interactions antifolates

A

use with potassium elevating drugs ef aldosterone antagonists, ACE inhibitorsm ARBs predisposes to hyperkalaemia.

Use with other folate antagonists eg methotrexate) and drugs that increase folate metabolism eg phenytoin, increases risk of haematological effects, t

rimethoprim can enhance the anticoagulant effect of warfarin by killing normal gut flora

42
Q

indications vancomycin

A

treatment of gram positive infection e.g. endocarditis, where infection is severe and/or penicillins cannot be used due to resistance e.g. MRSA. Treatment of antibiotic-associated colitis caused by c.diff infection

43
Q

unique adverse effects vancomycin

A

pain and inflammation of the vein (thrombophlebitis) at the infusion site,

if infused rapidly- anaphylactoid ‘red man syndrome’ - generalised erythema and may be associated with hypotension and bronchospasm. Anaphylactoid reactions are not true allergy - not antigen mediated.
However, true allergy can also occur.

IV can cause nephrotoxicity - including renal failure and interstitial nephritis,

ototoxicity with tinnitus and hearing loss

blood disorders including neutropenia and thrombocytopenia.

44
Q

how to decrease adverse effects vancomycin

A

requires careful monitoring of plasma concentrations and dose adjustment to avoid toxicity.

45
Q

side effect co-amoxiclav

A

cholestasis

46
Q

which macrolide to prescribe pregnancy

A

Erythromycin

PrEgnancy

Clarithromycin is contraindicated in pregnancy unless there is no alternative and the benefits outweigh the risks.

Finals pharmacology new (37 decks)

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