Beta-lactam allergy in pediatric population Flashcards
What is a drug allergy?
immunologically mediated drug hypersensitivity reaction
What is the classification of drug allergies?
immediate: occurring within 1 hour
- only IgE-mediated drug allergy falls into this category
non-immediate: occurring after 1 hour, but often days or weeks later
What are the 4 types of immune reaction?
Type 1: IgE-mediated (=<1-2 hours)
- urticaria/angioedema, respiratory distress, GI sx, hypotension, anaphylaxis
Type 2: cytotoxic (10 hr-wks)
- anemia, thrombocytopenia
Type 3: immune-complex (1-3 wk)
- serum sickness-like reaction: fever, urticaria, vasculitis, arthritis/arthralgia
Type 4: T cell-mediated (2-14 days)
- maculopapular rash, SJS, DRESS, acute generalized exanthematous pustulosis (AGEP)
What is the percentage of pen anaphylaxis?
< 1%
beta-lactam allergy: 5-8% (N America and Europe)
What increases the risk of beta-lactam allergy?
- parenteral
- long-term
- high-dose
(as compared to oral, intermittent therapy )
Does FamHx of beta lactam allergy increase risk?
- famhx beta-lactam allergy doesn’t increase risk
What is the percentage of Type 4 pen reaction (maculopapular exanthem)?
- 5% of adults (true allergy)
- 2% children
- Most due to infection & don’t contraindicate further use of antibiotics
What is the rate of beta lactam allergy?
5-8% (N America and Europe)
Why does misdiagnosis of drug allergy occur?
- due to misclassification of symptoms of illness or common SE of abx
- interaction b/w abx and pathogen can mimic reaction
- circulating beta-lactam-specific IgE antibodies decrease naturally over time (many kids not reassessed to delabel)
What is the rate of cross-reactivity between pen and cephalosporins?
- True rate 2%
* 1% in self-reported but unconfirmed allergy
What is the NPV and PPV of intradermal testing for penicillin?
- NPV 100% adults; 94% children —> less useful in children than adults
- PPV as low as 40% —> not helpful for screening
what are contraindications to Provocative drug challenges?
- hx consistent with previous recent anaphylaxis
- systemic, non-immediate immunologic reaction (serum sickness-like reaction, SJS, DRESS, drug-induced hemolytic anemia)
- recent data: going directly to oral challenge, without skin testing, more reliable
What are clinical implications of erroneous beta-lactam allergy labelling ?
- second-line non-beta-lactam antimicrobials inferior for infection management
- prolong hospital stays
- higher admission rate for ICU
- readmissions
- mortality
- Broad-spectrum antibiotics:
- resistance (VRE, MRSA)
- C diff infection
- Rising health care costs
- higher antibiotics costs per hospitalization
- prolonged hospital stays
How many pts non-allergic to pen could be identified by hx alone?
- 60% non-allergic could be identified by low-risk hx alone
How frequent should kids with pen allergies be seen by allergist?
after 5 yrs (can be outgrown)
What is management of kids with severe systemic or cutaneous delayed adverse reactions following pen?
- shouldn’t have abx in future
- future decisions for penicillin based on benefit vs risk
- avoid cephalosporins with similar side chains (some recommend)
- no robust evidence of cross-reactivity b/w penicillins and cephalosporins with similar side chains
- refer to allergist
What is management of kids with Suspected IgE penicillin allergy?
- don’t prescribe pen or cephalosporins with similar side chains
- refer to allergist
- dissimilar cephalosporin side chains can be prescribed
- provocative challenge to specific cephalosporin can be used (when necessary or certain cephalosporin desirable)
What is management of kids with mild, delayed exanthems following pen?
- don’t contraindicate future use abx
- single dose amoxil (15 mg/kg) with 1 hr observation provides reassurance & confirms no allergy
- can have cephalosporins (all), carbapenems, monobactams (without monitoring dose)
What is management of kids with suspected pen reaction who have since tolerated?
- not allergic –> no restrictions!
What do you ask on history when assessing drug allergies?
o Which medication and indication?
o How many courses of this med or related?
o How many doses before reaction?
o Concurrent medication?
o How soon after most recent dose did reaction occur?
o Nature of reaction? (photographs optimal)
o any symptoms of severe cutaneous drug reaction? (SJS, DRESS, AGEP)
o Symptoms of unexplained fever, arthritis/arthralgia, lymphadenopathy, skin exfolation or mucous membrane involvement?
o Was medication stopped?
o Medication attention sought? How was reaction managed?
o how long did symptoms last?
o Subsequent administration? reaction?
After doing a history, what are the next steps for a drug allergy? (to delabel the allergy)
- recent data: going directly to oral challenge, without skin testing, more reliable
- provocative drug challenge (unless previous recent anaphylaxis or serious drug reaction like SS, SJS, DRESS, hemolytic anemia)
