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3rd Year Drugs > Antibiotics Part 2 > Flashcards

Antibiotics Part 2 Flashcards

1
Q

Name aminoglycosides

A

Gentamicin

Amikacin

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2
Q

How do we give aminoglycosides

A

IV as they are highly polarised

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3
Q

Indications for aminoglycosides

A

1) Severe sepsis
2) Pyelonephritis and complicated UTI
3) Biliary and intra-abdominal sepsis
4) Endocarditis

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4
Q

What do aminoglycosides lack action against

A

Strep. and anaerobces

Hence combine them with penicillin and/or metronidazole when the organism is unkown

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5
Q

Action of aminoglycosides

A

Bind irreversibly to bacterial 30S ribosomes and inhibit protein synthesis

THey are bacteriocidial

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6
Q

Range of action of aminoglycosides

A

Epctrum includes gram -ve aerboic bacteria
Staphylococci
Mycobacteria

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7
Q

How do aminoglycosides enter bacteria

A

Via an oxygen dependent transport system

This is absent in strep and anaerobes hence they have innate resistance

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8
Q

ADVERSE Effects of Aminoglycosides

A

Nephrotxicity - potentailly reversibly
Ototoxicity –> may be ireversible

They accumulate in renal tubular epithelial and cochlear and vestibult hair cells –> here they trigger apoptosis and cell death

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9
Q

How does nephrotoxicitiy with aminoglycosides present

A

Reduced urine output

Increased urea and creatinine

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10
Q

How does ototoxcitiy with aminoglycosides present

A

Often not notived until after resolution of acute infection

May complain of hearing loss, tinnitus (cocheal damage) and vertigo (vestibular damage)

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11
Q

Warnigns of using aminoglycosides

A

Caregul monitoring or plasma conc. in neonates, elderly and renal impairment

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12
Q

Contraindications of aminoglycosides

A

Myasthenia gravis –> c an impair neuromuscular transmission

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13
Q

Interactions of aminoglycosides

A

1) Loop diuretics or vancomycin –> increased risk of ototoxictiy
2) Ciclosporin, platinum chemotherapy, cephalosporins, vancomycin –> increased risk of nephrotoxicity

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14
Q

Name cepaholosprins

A

Cefalexin

Cefotaxime

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15
Q

Name carbapenems

A

Meropenem

Ertapenem

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16
Q

Indicatiosn for cepaholosporins and carbapenens

A

1) 2nd and 3rd line treatment for urinary and respiratory tract infections –> oral cephalosporins
2) Very severe/complicated infections caused by antibitoics resitant organisms –> reserve IV ccephalosporins and carbapenems for this

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17
Q

Actions of cepaholosporins and carbapenems

A

Inhibit enzyme responsible for cross linking peptidoglycans in bacterial cell walls –> cant maintain an osmotic gradient –> bacterial cell swilling –> lysis and death

Both have a broad spectrum of activity

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18
Q

Why are cepaholosporins and carbapenems more resistant to beta lactamases then penicillines

A

As the fusion of a beta lactam ring with a dihydrothiazine ring (cephalosporins and a unique hydroethyl side chain in carbapenems

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19
Q

Adverse effects of cepaholosporins and carbapenems

A

1) GI upset
2) Hypersesntivity
3) CNS toxicity –> including seizures. Particularly with high dose carbapenems in those with renal impairment

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20
Q

Warnings of using cepaholosporins and carbapenems

A

Risk of C. DIff

Caution of carabapenems and epilepsy

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21
Q

Interactinos of cepaholosporins and carbapenems

A

Can enhance warfarin effect

Cephalosporins increase the nephrotoxicty of aminoglycosides

Carbapenems decrease the plasma conc. and efficacy of valproate

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22
Q

Name the pencillin with anti-pseudomonal action

A

Piperacillin with tazobactam aka Tazocin

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23
Q

Indication of anti-pseudomonal penicillin

A

Severe infections - particularlly when there is a broad spectrum of potential pathogens
Antibitoic resistance is likely (i.e. hospital acquired infetions)

Immunocompromised patients

24
Q

Specific clinical infections treated with tazocin

A

1) LRTI
2) Intra-abdominal sepsis
3) UTI
4) Skin and soft tissue infections

25
Q

Why does tazocin have activity against pseudomonas

A

As in piperacillin the side chain has been converted to a form of urea

This increases activity to include pseudomonas

Tazocin is a beta-lactamase inhibitor –> therefore has activity against beta-lasctamase producing bacteria e.g. S. Aureus and gram-ve anaerobes

26
Q

Adverse effects of anti-pseudomonal penicllines

A

1) GI Upset
2) antibiotic associated colitis
3) Hypersensitivity

27
Q

Warning of using tazocin

A

1) Caution if risk of C. DIff infection

2) Reduce dose in moderate/severe pencillin allergy

28
Q

Interactions of tazocin

A

1) Methotrexate - reduces renal excretion hence increased risk of toxicity
2) enhances warfarin

29
Q

can you get tazocin in the community

A

No 0 it is hospital only

Each dose of tazocin contains about 10mmol of Na and is infused in 50-150mls of fluid

Remember to take this into account when determining the need for supplementary fluid, particularly in heart failure.

30
Q

Name broad-spectrum penicllines

A

Amoxicillin

Co-amoxiclav (amoxicllin and clavulinac acid)

31
Q

Indications for the use of broad-spectrum antibiotics

A

1) empirical pneumonia treatment - due to gram +ve (S. pneumonia) or gram -ve (H. Influenzae)
2) Empirical UTI treatment (most commonly due to E. Coli)
3) Part of combo treatment for intra-abdominal sepsis or hospital acquired infections
4) Part of treatment for H. Pylori associated ulcers

32
Q

Action of broad-spectrum antibitoics

A

Inhibits enzymes that cross-link peptidoglycan in bacterial cell walls - weakened walls cant maintain osmontic gradient –> uncontroled water entry –> lysis and death

33
Q

Why does amoxicllin hace increased activity against gram-ve bacteria

A

As in amoxicillin the addition of an amino group o the beta-lactam ring increases their activity against gram-ve bacteria

Hence this makes them more broad spectrum

34
Q

What is co-amoxiclav

A

Amoxicillin and clavulanic acid

35
Q

What is the action of clavulanic acid in co-amoxiclav

A

It is a beta-lactamse inhibitor

THis increases the spectrum of cover further to include beta-lactamse producing bacteria (S. aureus and gram-ve anaerobes)

36
Q

Adverse effects of broad spectrum penicillins

A

1) GI Upset
2) Antibiotic associated collitis
3) Allergy

37
Q

Warnings of broad spectrum penicillin

A

1) caution if risk of C. diff e.g. hospital or elderly

2) Lower dose in severe renal impairment –> risk of crystaluria

38
Q

Interactions of broad spectrum penicillin

A

1) Methotrexate - reduces renal exretion, hence increasd risk of toxicity
2) Enhance warfarin

39
Q

Name penicillinase resistant penicillins

A

Flucloaxcillin

40
Q

Indications of flucloxacillin

A

STAPHYLOCOCCAL INFECTIONS e.g.

1) Skin and soft tissue
2) Osteomyeltis and septic arthritis
3) Endardatiis

41
Q

How does flucloxacillin have activity against beta-lactamase producing bacteria

A

It has an axyl side chain on the beta-lactam ring

This protects the ring from beta-lactamases

42
Q

How does MRSA resist flucloaxcilllin

A

It reduces the penicillin binding affinity

43
Q

Adverse effects of flucloxacillin

A

1) GI Upset
2) Allergy
3) Liver toxicity –> including cholestasis and hepatitis
4) CNS toxicity - in high doses or severe renal impairment

44
Q

Warninngs of flucloxacillin

A

1) Renal failure - may require dose reduction

45
Q

Interactions of flucloaxcillin

A

2) Methotrexate - redudces its renal excretion hence increased risk of toxicity

46
Q

How long should you give flucloxacillin for deep seated infections

A

6 weeks e.g. endocarditis and osteomyelitis

It has a short plasma half life and is rapidly renallyexcreted hence give every 6 hours

47
Q

Name standard penicllins

A

Benzylpenicillin

Phenoxymethylpenicillin (penV)

48
Q

Indications for pencillin

A

1) Streptococcal infection - includes tonsilitis, pneumonia (with macrolide if severe), endocarditis, skin & soft tissue infections (with flucloxacillin if severe)
2) Clostridial Infections e.g. tetanus
3) Meningococcal infections e.g. meningitis and septicaemia

49
Q

actions of penicillins

A

Inhibits the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls

50
Q

How do bacteria acquire resistance to pencillins

A

Bacteria make beta-lactamase enzymes

This breaks the beta-lactam ring

51
Q

How common are pencillin allergy

A

affects 1-10% of people
Usually skin rash 7-10 days after first exposure or 1-2 days after repeat

Less commonly is an anaphylactoid reaction - hypotension, bronchial spasm, angioedema

52
Q

Adverse effects of pencillins

A

1) allergy

2) CNS Toxicity –> including convulsions and coma

53
Q

Warnings of using penicillins

A

1) Renal Impairment

54
Q

Interactions of penicillins

A

1) methotrexate - reduces its renal excretion hence increased risk of toxicity

55
Q

How can you give benzypenicillinsn

A

IV or IM as hydrolysis by gastric acid prevents GI absorption

56
Q

How can you give PenV

A

It is stable in gastric acid hence can be given orally

57
Q

What would you prescrive for young person with a sore throat

A

If it requires antibitoics GIVE PENV (not amoxicillin)

This is because if the sore throat due to EBV amoxicillin it causes rash - mistaken for allergy

3rd Year Drugs (10 decks)

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