Lecture 6 - general principles of treatment Flashcards

1
Q

Difference between primary and secondary prophylaxis ?

A

1 - prevent initial infection

2- prevent recurrent episodes

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2
Q

Name the five questions asked in accurate diagnosis of an infection

A
1- infection?
2- source?
3- microorganism?
4- need antibiotics or self limiting?
5- urgent or can diagnosis me made?
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3
Q

If a positive culture has been identified, when would you not start antibiotics ?

A

if culture is from a non sterile sit e.g. wounds

could just be colonisation

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4
Q

When would you use a broad spectrum antibiotic (2) what is the risk (1)

A

when microbiology is uncertain or infection is caused by a mixture of organisms. promotes resistance

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5
Q

What 5 things must you consider when evaluating if the drug is safe to give a particular patient

A

1) does the patient have impaired excretion
2) any drug interactions with preexisting prescriptions
3) is there a high risk of toxic effect e.g. CNS toxicity in epileptic, BM toxicity in transplant patients
4) does the patient have a known hypersensitivity?
5) is there a risk of Abx associated diarrhoea

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6
Q

When would a bacteriostatic antibiotic be effective?

A

if the toxin is the main pathogenic agent, bacertiocidal drugs would cause lysing of cells and therefor release more toxins

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7
Q

Name three situations when bacteriocidal drugs are preferred

A
the immunocompromosed (ill or stedoid therapy)
the immunodeficient (neutropenia or HIV)
difficult sites (meningitis or endocarditis)
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8
Q

Name some positives of changing from iv to oral antibiotics

A
reduces potential of line infection
saves nursing time
reduces patient discomfort
reduces treatment costs 
reduce risk of adverse effects
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9
Q

What is the criteria for changing from iv to oral antibiotics

A

Clinical improvement observes
Oral route is not compromised
Markers showing trend towards normalising
Specific indication/ deep seated infection

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10
Q

How long should most infections take to respond to treatment?

A

5-7 days according to severity of condition

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11
Q

What is outpatient parenteral antibicrobial therapy and when is it appropriate?

A

iv at home - long term semi-permanent line and self administered. used in long term treatment to reduce hospital bed days and less hospital acquired infections

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12
Q

Give three reasons why combination therapy would be more effective than monotherapy

A

broader spectrum cover
prevent resistance e.g. tb
synergistic e.g. penicillin and gentamicin

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13
Q

State two negatives to combination therapy

A

increase costs and increased risks of toxicity

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14
Q

When is it appropriate to give oral vancomycin and not systemic

A

with infections in the gut e.g. cdiff. dont use oral for systemic infections as wont work - use iv

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15
Q

Name 4 situations that may need extra considerations when prescribing

A

pregnancy
lactation
newborn
old age

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16
Q

Name some of the pharmacokinetic considerations in newborns

A
  • high ECF volume so lower plasma conc of drug
  • immature hepatic enzymes
  • lower g6pD concs (risk haemolysis)
  • renal immaturity (30-60% of adult GFR)
  • prolonged half life and raised cMAX
17
Q

Name some infection risks in pregnant women

A
URTI
LRTI
UTI
interuterine infection
amnionitis
18
Q

Name 5 antibiotics that are contraindicated in pregnancy (and what they cause)

A

sulphonamides (kernicterus), streptomycin (ototox), tetracyclines (tooth discolour and bone growth interfere), chloramphenicol (CV collapse), sulfonamides and nitrofurantoin (haemolysis)

19
Q

which antibiotic should you avoid when breast feeding and why

A

metronidazole as 1:1 serum to breast milk ratio

20
Q

when may Abx treatment in the elderly not be effective?

A
  • organ function in decline
  • often affected by multiple diseases/ on multiple long term meds
  • compliance may be compromised
21
Q

Name some of the pharmacokinetic considerations of the elderly

A
  • reduction in total bod water + distribution
  • GI surgery?
  • ph altered by drugs or diseases?
  • hepatic involution
  • reduced GFR with age
  • lower renal blood flow
22
Q

Name 6 life threatening infections that require immediate treatment

A

Meningitis, meningococcal sepsis, epiglottitis, encephalitis, Necrotising fascilitis, toxic shock syndrome

23
Q

Name some factors involved in the selection of appropriate antibiotic therapy

A

site of infection, seriousness, likely organism, patient circumstances, cost, toxicity and side effects, local/ national resistance rates, other underlying disease, contraindications

24
Q

What pharmokinetics must be considered when prescribing?

A

absorption (bioavailability, food, other drugs) distribution (serum tissue concs, protein binding, crossing natural boundaries), metabolism (half life), excretion

25
Q

Name three questions that must be asked when considering HOW much drug to dose a patient with

A
  • do they need a loading dose?
  • do they have renal failure (some drugs will need reduced dose)?
  • does dose need to be done by weight?
26
Q

Name three bacteriocidal drugs and there bacteriostatic

A
CIDAL = penicillin, ciprofloaxin and gentamycin 
STATIC = tetracyclines and sulphonamides
27
Q

What kind of infections would need to be treated longer?

A

deep seated infections e.g. liver abscess, osteomyelitis, empyema, cavitating pneumonia

28
Q

Name four drugs that have reduced elimination in the elderly

A

penicillins, cephalosporins, vancomycin and aminogycosides