Hypersensitivity reactions to beta-lactam antibiotics can be classified into:
Immediate Reactions (within 1 hour)
1. Anaphylaxis: severe, life-threatening allergic reaction
2. Urticaria (hives)
3. Angioedema (swelling of face, lips, tongue)
4. Bronchospasm (asthma-like symptoms)
5. Hypotension (low blood pressure)
Delayed Reactions (within 24-72 hours)
1. Maculopapular rash
2. Erythema multiforme (skin lesions)
3. Stevens-Johnson syndrome (severe skin and mucous membrane lesions)
4. Toxic epidermal necrolysis (skin blistering and peeling)
5. Interstitial nephritis (kidney inflammation)
Mechanisms:
1. IgE-mediated (immediate reactions)
2. IgG-mediated (delayed reactions)
3. Cell-mediated immunity (T-cell mediated)
Risk Factors:
1. Previous beta-lactam allergy
2. Family history of beta-lactam allergy
3. Concurrent viral infections
4. Immunocompromised patients
5. High-dose or prolonged beta-lactam therapy
Beta-lactam Antibiotics Most Commonly Associated with Hypersensitivity:
1. Penicillin G
2. Amoxicillin
3. Cephalosporins (especially 1st and 2nd generation)
Management:
1. Immediate discontinuation of beta-lactam antibiotic
2. Administer epinephrine (anaphylaxis)
3. Antihistamines (urticaria, angioedema)
4. Corticosteroids (delayed reactions)
5. Desensitization (in some cases)
Cross-Reactivity:
1. Penicillins and cephalosporins: 1-10% cross-reactivity
2. Carbapenems and monobactams: lower cross-reactivity
Diagnostic Tests:
1. Skin prick test
2. Intradermal test
3. Radioallergosorbent test (RAST)
4. Enzyme-linked immunosorbent assay (ELISA)
Prevention:
1. Careful medical history
2. Allergy testing (if necessary)
3. Gradual dose escalation
4. Monitoring for signs of hypersensitivity
It’s essential to recognize and manage hypersensitivity reactions promptly to prevent severe consequences.
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