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PR3151 (cleefy) > IC7 PR3151 Principles of antimicrobial use > Flashcards

IC7 PR3151 Principles of antimicrobial use Flashcards

1
Q

what is the systematic approach to abx use

A

1) confirm the presence of inf
2) determine pathogen
3) select antimicrobial
4) monitoring

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2
Q

what to do in step 1 of abx use

A

CONFIRM presence of infection:

1) risk factors
2) subjective
3) objective
4) potential site of infection

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3
Q

what are the risk factors for infection

A

1) age
2) immunosuppression
3) disruption of protective barriers
4) alterations to host flora

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4
Q

what are some examples of pyretic drugs

A

thyroid medications
anti-epileptics
beta-lactams

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5
Q

what are some subjective signs of infection

A

systemic and localised signs

Localised symptoms
* Diarrhoea, nausea, vomiting, abdominal distension
* Cough, purulent sputum
* Dysuria, frequency, urgency
* Pain and inflammation at site of infection – erythema, swelling, warmth
* Purulent discharge (wound, vaginal, urethral)

Systemic symptoms
* Feverish, chills, rigors
* Malaise
* Palpitations
* Shortness of breath
* Mental status changes
* Weakness

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6
Q

what are some objective signs of an infection?

A

vital signs
- fever > 38
- SBP < 100
- RR > 22
- HR >90
- glascow coma scale

lab tests
- TW
- neutrophils
- CRP
- ESR
- procalcitonin

radiology

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7
Q

what is the TW suggestive of an infection?

A

10 x 10^9 /L

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8
Q

what is the neutrophil count suggestive of an infection

A

> 75%

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9
Q

what is the CRP suggestive of an infection?

A

> 40mg/L

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10
Q

what is the procalcitonin suggestive of an infection?

A

> 0.5micrograms/L

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11
Q

difference between pathogen, coloniser and contaminant
provide some examples of the latter 2.

A

pathogen
- invade tissue and cause host immune response
- may be picked up from external environment or from the normal flora

coloniser
- from natural host flora but does not cause immune response
e.g., yeast

contaminant
- from external sources
e.g., s epidermis and bacillus from blood samples

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12
Q

how to find the difference between pathogen, coloniser and contaminant

A

1) single or mix growth?
2) signs and symptoms
3) consider whether the pathogen is usually found at the site of infection
4) consider epidemiology and likelihood of cause of disease
5) signs of tissue invasions
6) isolated from a single cell culture?

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13
Q

what are the 3 steps to antimicrobial selection?

A

organism, host (patient), and drug factors

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14
Q

benefits of combination therapy

A

increase the spectrum of activity, reduce incidence of resistance, synergistic effect

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15
Q

what is one example of synergistic effect

A

ampicillin + gentamicin OR ceftriaxone for enterococcal species

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16
Q

which penicillins have similar r1 side chains

A

pencillin G and V

17
Q

which penicillins vs cephalosporins have similar r1 side chains

A

ampicillin vs cefalexin

18
Q

which cephalosporins have similar r1 side chains

A

ceftriaxone vs cefepime

ceftazidime vs aztreonam

19
Q

what is the rate of cross reactivity in penicillins vs cephalosporins and carbepenems

A

<2 and <1% respectively

20
Q

(penicillin allergy history and management) what to use if patient has a severe immediate penicillin allergy

A

OKAY:
- non beta lactam antibiotics
- aztreonam

NOT OKAY
- non cross rxt cephalosporins abx can still be used but with close monitoring
- penicillins and cross rx cephalosporins unless (1) skin prick / intradermal followed by drug challenge OR (2) desensitisation

21
Q

(penicillin allergy history and management) what to use if patient has a NON-severe immediate penicillin allergy

A

OKAY:
- non beta lactam
- aztreonam
- carbapenems
- non cross rx cephalosporins

NOT OKAY
- penicillins and cross rx cephalosporins unless (1) skin prick / intradermal followed by drug challenge OR (2) desensitisation

22
Q

(penicillin allergy history and management) what to use if patient has a severe delayed (type 4) penicillin allergy

A

OKAY:
- non beta lactam
- aztreonam

NOT OKAY
- penicillin carbapenem cephalosporins
- avoid desensitisation

23
Q

(penicillin allergy history and management) what to use if patient has a non severe delayed (type 4) penicillin allergy

A

OKAY:
- non beta lactam
- aztreonam
- carbapenems
- cephalosporins

  • can consider penicillins with close monitoring
24
Q

what are the antibiotics with good csf penetration

A

linezolids, penicillins, 3-5 gen cephalosporins, meropenem, vancomycin, aztreonam

25
Q

what are abx with poor csf penetration

A

1-2 gen cephalosporins, aminoglycosides, macrolides, lincosamides

26
Q

what are the different types of killing for antibiotics

A

time dependent
conc dependent
exposure dependent

27
Q

what are the qualities of conc dependent killing? list benefits and examples

A

high doses with extended intervals, e.g., one single extended dose.

e.g., aminoglycossides
- reduces cost
- reduce the chance of resistance
- reduce nephrotoxicity as the tubules are already saturated.
- post antibiotic effect (pae)

28
Q

aminoglyclosides target cmax/mic

A

8-10

29
Q

recall hartford nomogram for gentamicin

A

dosing:

if TBW <30% IDW: use TBW

if TBW > 30% IDW: use adjBW
adjBW = 0.4*(TBW-IBW)+IBW

30
Q

gentamicin dosing

A

5-7mg/kg
once-daily dosing
peak: 16-24mg/ml
trough <1 mg/ml

31
Q

time dependent killing qualities

A

time > mic should be 40-70%

in cases where the pt is critically ill or there is poor concentration at the target site:
time > MIC should be 4-5x at 5-100 percent of the dosing interval

32
Q

examples of drugs with concentration dependent killing

A

fluroquinolones
ahminoglycosides
metronidazole

33
Q

examples of drugs with time dep killing

A

CCP - M
beta lactams: carbapenem, cephalospor, penicillin, monobactams

34
Q

examples of drugs with AUC dependent killing

A

CLMT V
clinda
linezolid
macrolide
tetracycline
vancomycin

35
Q

vancomycin AUC/MIC dosing

A

400-600

36
Q

fluoroquinolones dosing

A

gram (+) auc/mic >30
gram (-) auc/mic > 125, cmax/mic: 8-12

37
Q

strategies to improve time depedent killing

A

1) block excretion via probenecid
2) increase frequency of admin
3) continuous infusion (iV)

38
Q

MINDME for ABX stewardship

A

Microbiology guided
Indication is evidence-based
Narrow spectrum
Dose is appropriate
Minimise duration of therapy
Ensure monotherapy

PR3151 (cleefy) (12 decks)

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