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Microbiology and ID > Aminoglycosides > Flashcards

Aminoglycosides Flashcards

1
Q

What is the general action of aminoglycosides?

A

Bactericidal

Inhibit bacterial protein synthesis - targets 30S ribosomes

Leads to cell death

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2
Q

Name some common aminoglycosides

A

Streptomycin

Gentamicin

Neomycin

Kanamycin

Paromomycin

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3
Q

What are the indications for gentamicin?

A

Bacterial eye infection

Bacterial infection in otitis externa

Moderate - severe diabetic foot infection

Acute diverticulitis

Leg ulcer infection

Gram +ve bacterial / HACEK endocarditis

Septicaemia

Meningitis and other CNS infections

Biliary-tract infections

Endocarditis

Pneumonia in hosp patients

Adjunct in listerial meningitis

Prostatitis

CNS infections

Surgical prophylaxis

Acute pyelonephritis

UTI

Uncomplicated gonorrhoea

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4
Q

Describe the pharmacokinetics of gentamicin

A

Bioavailability = given via IV

Protein binding = 0-30%

Half-life = 75 mins after IV

Metabolism = little to none

Excretion = 70% kidneys via urine

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5
Q

What are the contraindications for all aminoglycosides?

A

Myasthenia gravis

(aminoglycosides may impair neuromuscular transmission)

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6
Q

What are the contraindications for gentamicin?

A

Patent grommet

Perforated tympanic membrane

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7
Q

What are the common/very common side effects of aminoglycosides?

A

Aphonia

appetite decreased

bronchospasm

chest discomfort

cough

deafness

diarrhoea

dizziness

dysphonia

fever

haemoptysis

headache

increased risk of infection

nausea

oropharyngeal pain

renal impairment

skin reactions

taste altered

tinnitus

vomiting

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8
Q

What types of toxicities are associated with aminoglycosides?

A

Ototoxicity

Nephrotoxicity

N.B. Gentamicin is considered to be more vestibulotoxic than cochleotoxic compared to other aminoglycosides

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9
Q

What are signs of ototoxicity?

A

issues with balance

nausea

tinnitus

hearing loss

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10
Q

What are signs of nephrotoxicity?

A

high plasma creatinine

high urea

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11
Q

What monitoring is required for gentamicin?

A

For multiple daily dose regimen, one-hour (‘peak’) serum concentration should be 5–10 mg/litre; pre-dose (‘trough’) concentration should be less than 2 mg/litre.

For multiple daily dose regimen in endocarditis, one-hour (‘peak’) serum concentration should be 3–5 mg/litre; pre-dose (‘trough’) concentration should be less than 1 mg/litre. Serum-gentamicin concentration should be measured after 3 or 4 doses, then at least every 3 days and after a dose change (more frequently in renal impairment).

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12
Q

What are the significant drug interactions for gentamicin?

A

Gentamicin + Ataluren/Colistimethate = increased risk of nephrotoxicity

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13
Q

According to UHS MicroGuide in which situations should you avoid giving gentamicin?

A

All decompensated cirrhotics i.e., Child Pugh score ≥ 7, irrespective of presence or absence of ascites

All those listed for liver transplantation irrespective of Child-Pugh score

All cirrhotics with baseline renal impairment (CrCl < 60ml/min), irrespective of Child Pugh score

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14
Q

According to UHS MicroGuide if a patient has a CrCl < 20mL/min should you give gentamicin?

A

No

Discuss alternatives with microbiology

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15
Q

According to UHS MicroGuide, when treating a patient for endocarditis what dosing should be used for gentamicin?

A

Multiple daily dosing regime

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16
Q

How do you calculate CrCl?

A

Using the Cockcroft-Gault equation

{((140–age in years) x weight in kg)/(72xSCr)}x 0.85 (if female)

SCr (serum creatinine) = mg/dL

https://www.kidney.org/professionals/kdoqi/gfr_calculatorcoc

17
Q

According to UHS MicroGuide, what initial dose of gentamicin should you give for all patients?

A

IV 5mg/kg (round to nearest 10mg)

Usual max single dose of 480mg

18
Q

For gentamicin dosing can you just use actual body weight?

A

No

Need to use ideal body weight

19
Q

How do you calculate ideal body weight in males?

A

50 + 2.3 x (each inch over 5 foot in height)

20
Q

How do you calculate ideal body weight in females?

A

49 + 1.7 x (each inch over 5 foot in height)

21
Q

A patient has normal renal function (i.e., CrCl > 60mL/min). According to UHS MicroGuide, what dose of gentamicin should they be given?

A

5mg/kg OD

22
Q

According to UHS MicroGuide, when would you need to measure the trough level for gentamicin for a patient with normal renal function?

A

If > 2 doses are being administered

23
Q

According to UHS MicroGuide, when do you measure the trough level for gentamicin for someone with normal renal function?

A

20 hours post 2nd dose

24
Q

According to UHS MicroGuide, for patients on gentamicin with normal renal function if the trough level is < 1mg/L what should you do?

A

Continue with 5mg/kg OD

Measure trough level 20 hours post dose every 1-2 days

25
Q

According to UHS MicroGuide, for patients on gentamicin with normal renal function if the trough level is > 1mg/L what should you do?

A

DO NOT give gentamicin

Re-check trough level every 12 hours

Once trough level < 1mg/L re-dose at 3mg/kg

Measure trough level 20 hours post dose

26
Q

A patient has impaired renal function (i.e., CrCl < 60mL/min) or they are ≥ 80 years. According to UHS MicroGuide, what dose of gentamicin should they be given?

A

IV 5mg/kg STAT DOSE ONLY

27
Q

When would you measure the trough level for a patient with impaired renal function (i.e., CrCl < 60mL/min) or they are ≥ 80 years, according to UHS MicroGuide?

A

After every dose

28
Q

According to UHS MicroGuide, for patients on gentamicin with impaired renal function or they are ≥ 80 years, if the trough level is < 1mg/L what should you do?

A

Re-dose with 3mg/kg once daily

Measure trough level 20 hours post dose

29
Q

According to UHS MicroGuide, for patients on gentamicin with impaired renal function or they are ≥ 80 years, if the trough level is > 1mg/L what should you do?

A

Do NOT give gentamicin

Re-check trough level every 12 hours

Once trough level <1mg/L, re-dose at 3mg/kg

Measure trough level 20 hours post dose

30
Q

According to UHS MicroGuide, for the multiple daily dosing regime for endocarditis what dose of gentamicin should be given?

A

IV 1mg/kg BD (round dose to nearest 10mg/maximum dose 80mg BD)

31
Q

According to UHS MicroGuide, for the multiple daily dosing regime of gentamicin for endocarditis what should be the aim trough and when do you measure this?

A

< 1mg/L

Immediately pre-dose

Measure levels around 3rd dose after starting or dose change; otherwise 2ce weekly if renal function is stable

32
Q

According to UHS MicroGuide, for the multiple daily dosing regime of gentamicin for endocarditis what should be the aim peak and when do you measure this?

A

3-5mg/L

One-hour post dose

Measure levels around 3rd dose after starting or dose change; otherwise 2ce weekly if renal function is stable

33
Q

According to UHS MicroGuide, for the multiple daily dosing regime of gentamicin for endocarditis if the patient has high trough or peak levels what should you do?

A

Do NOT give next dose

If trough level > 1mg/L, increase dosage interval e.g., from 2ce daily to 1ce daily

If peak level > 5mg/L, decrease dose

N.B. Linear kinetics so 10% dose reduction should give 10% reduction in levels

34
Q

Which bacterial cover dose gentamicin, tobramycin and amikacin have?

A

Gram negative bacilli i.e., Pseudomonas, E.coli, Klebsiella, ESCAPPM

35
Q

What are the ESCAPPM/ESCAHAPPM microbials?

A

E: Enterobacter spp.
S: Serratia spp.
C: Citrobacter freundii
H: Hafnia spp.
A: Aeromonas spp.[citation needed]
P: Proteus spp. (excluding P. mirabilis)
P: Providencia spp.
M: Morganella morganii

https://en.wikipedia.org/wiki/ESCAPPM

Microbiology and ID (5 decks)

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