antibiotics

1. Allergies to Antimicrobials

2. Course content
Course
roadmap
Basic concepts
Common infections
2

3. “This may even bring the end of
modern medicine as we know it.
We need to act now to make sure
this does not happen.”
Dr. Margaret
Chan
New York, USA
18 April 2016
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4. Core competencies for
antimicrobial prescribing
C1: Understands the patient and the patient’s clinical needs
C2: Understands treatment options and how they support the
patient’s clinical needs
C3: Works in partnership with the patient and other healthcare
professionals to develop and implement a treatment plan
C4: Communicates the treatment plan and its rationale clearly to
the patient and other health professionals
C5: Monitors and reviews the patient’s response to treatment
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Core Competencies

5. Objectives
• Recognize that the majority of reported penicillin allergies are
not confirmed upon testing and expose patients to undue
harm
• Understand when diagnostic testing, including skin testing, is
indicated to confirm an antimicrobial allergy
• Employ strategies to determine if cephalosporins can be used
in patients with reported penicillin allergies.
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6. Antibiotic Allergies
Complicate choice of therapy
PCN most common
Limited confirmatory testing
Leads to costly ineffective treatment
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7. Antibiotic Allergies
De-labeling
removal of the false indication of
antibiotic allergy from a patient’s
record.
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8. Categorization of Allergies
Drug Allergy
drug hypersensitivity reaction that
is mediated by a patient’s
immunologic response to a drug
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9. Categorization of Allergies
Immediate reaction
• Occur rapidly
• IgE mediated
– Urticaria
– Angioedema
– Anaphylaxis

10. Categorization of Allergies
Immediate reaction
• Occur rapidly
• IgE mediated
– Urticaria
– Angioedema
– Anaphylaxis
Delayed reactions
• Occur later
• Most commonly T-cell
mediated
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11. Timeline to establish relationship
between drug and symptoms
Diagnosis of drug allergy
11

12. Diagnosis of drug allergy
Immediate
reaction
Severity
Drug
Prior exposure
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13. Diagnosis of drug allergy
Severe
reactions
Anaphylaxis
SJS/TEN
DRESS
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14. Severe reactions
Anaphylaxis
Hives, flushing, itching, erythema,
angioedema followed by
respiratory compromise
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15. Severe reactions
Stevens-Johnson
syndrome (SJS)
Toxic epidermal
necrolysis (TEN)
Extensive necrosis and
detachment of the epidermis
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16. Severe reactions
Drug Reaction
Eosinophilia
Systemic
Symptoms
(DRESS)
Fever, facial edema, rash
Eosinophilia, transaminitis and/or
end organ failure
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17. Diagnosis of drug allergy: Testing
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• ~80% of patients do not
react upon repeat
exposure
• Objective testing helpful

18. Diagnosis of allergy: Testing
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Tryptase
In vitro testing
Skin testing
Graded dose challenge
Patch testing

19. Diagnosis of allergy: Testing
19
Tryptase
In vitro testing
Skin testing
Graded dose challenge
Patch testing

20. Skin Testing
• Used for immediate reactions
• Skin prick test followed by
intradermal
• Contraindicated in patients
with:
– history of severe anaphylaxis,
– certain skin conditions
– certain medications
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WHO/ E. Robilotti

21. Skin Testing
• A negative skin test does not
exclude a drug allergy
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WHO/ E. Robilotti

22. Diagnosis of allergy: Testing
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Tryptase
In vitro testing
Skin testing
Graded dose challenge
Patch testing

23. Graded Dose Challenge
Used for patients unlikely to be
allergic
Skin prick test followed by
intradermal
Perform in a controlled
setting
protocols start with low doses
A negative challenge does not
absolutely mean the patient will
not develop an allergic reaction
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24. Diagnosis of allergy: Testing
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Tryptase
In vitro testing
Skin testing
Graded dose challenge
Patch testing

25. Penicillin allergies
Immediate Hypersensitivity
Delayed Hypersensitivity
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26. Penicillin Skin Testing
• Common
• Uses penicillin degradation
products = Major and minor
determinants
• Skin prick test followed by
intradermal
• Positive skin test + history can
confirm penicillin allergy
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WHO/ E. Robilotti

27. Case 1
Subsequent evaluation
Initial evaluation
Clinical
assessment
Diagnostic
work-up
Patient
education
Therapeutic
decisions
Modify
antimicrobials
Data
review
Clinical
re-assessment
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Core Competencies 1, 2, 3 & 5

28. 25 y/o pregnant female (16 weeks)
Treponema pallidum enzyme
immunoassay positive
RPR 1:16
HIV negative
gonorrhea and chlamydia negative
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29. Penicillin skin testing for
treatment of syphilis in pregnancy
• If skin testing negative 
perform graded dose
challenge
• If skin testing positive 
patient should undergo
desensitization
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WHO/ E. Robilotti

30. Case 1
Subsequent evaluation
Initial evaluation
Clinical
assessment
Diagnostic
work-up
Patient
education
Therapeutic
decisions
Modify
antimicrobials
Data
review
Clinical
re-assessment
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• Skin testing = negative
• Graded challenge with
penicillin tolerated
Core Competencies 1, 2, 3 & 5

31. Case 1
Subsequent evaluation
Initial evaluation
Clinical
assessment
Diagnostic
work-up
Patient
education
Therapeutic
decisions
Modify
antimicrobials
Data
review
Clinical
re-assessment
31
• Given benzathine
penicillin G
Core Competencies 1, 2, 3 & 5

32. Case 2
Subsequent evaluation
Initial evaluation
Clinical
assessment
Diagnostic
work-up
Patient
education
Therapeutic
decisions
Modify
antimicrobials
Data
review
Clinical
re-assessment
32

33. 65 y/o male planned for hip arthroplasty
Vague history of penicillin reaction
Skin testing if available
Review history of abx consumption
Timing of reaction is important
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34. Caring for Patients with Allergies
Avoid unnecessary antimicrobials
Prevent Infections
• Control comorbidities
• Vaccinate
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35. Review: Antimicrobial Allergies
Drug
Dose
Duration
Route
prescription
.............
.............
.............
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36. Review: Antimicrobial Allergies
Drug
Dose
Duration
Route
prescription
.............
.............
.............
Majority of penicillin allergies are
not confirmed upon testing.
False allergies expose patients to
harm.
Testing can assist clinicians in
evaluating immediate reactions.

37. Review: Antimicrobial Allergies
Avoid unnecessary antimicrobials
in patients with drug allergies.
Drug
Dose
Duration
Route
prescription
.............
.............
.............

38. Quiz time!
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