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Antimicrobial allergy

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9 Oct 2021

Allergy due to antimicrobials is the most common and fatal cause of morbidity. Measuring histamine levels, High molecular weight neutrophil chemotactic factor, and prostaglandin D2 metabolites help in the identification of various forms of the reactions. They are categorized by the type of allergy mediated by the drug and the particular time used by the drug to show in symptoms. it is mostly through the immunologic response provided by a drug to the system. Either Immediate or delay reaction can be seen. the immediate reaction is through IgE mediated antibodies and delay occurs through T-cells. Immediate reactions occur after the absorption of the drug in the body and delay reaction occurs after several days of taking. the diagnosis of the allergy is based on the severity of the reaction. a reaction such as anaphylaxis, steven-Johnsons syndrome(SJS), Drug reaction Eosinophilia systemic symptoms (DRESS), and toxic epidermal necrolysis (TEN).

The diagnosis is mostly done through:

  1. Skin testing

  2. Penicillin testing

  3. Graded dose testing

A) Skin testing: It is used to identify if the person shows an immediate reaction to the drug.

B) Penicillin skin testing: The person is given a skin prick test followed by an intradermal. redness around with spots indicates a positive skin test.

C)Graded dose challenge: This is mostly used for patients who are unlikely to develop allergies. low doses are firstly given.


While selecting up the antimicrobials, clinical assessment with diagnostic workup, history, and data review should be considered. The risk factors associated with drug allergy are nature of the drug, degree of exposure, age, genetic factor, multiple allergy syndromeRoute of administration, and previous drug reaction.


Commonly causing allergic reactions with drugs are:

1) Antibiotics

Drug: Penicillin allergy



  • Sulfonamides can cause steven-johnsons syndrome(SJS).

  • Trimethoprim and trimoxazole lead to aseptic meningitis.

  • Cephalosporin leads to serum sickness.

2)NSAID'S(Non-steroidal anti-inflammatory drugs)

  • Ibuprofen and naproxen causes allergic reaction.

  • Symptoms: Itching, nasal congestion, and wheezing.

3)Sulfa drugs

people who have an increased risk of antibiotic allergy have an increased risk of sulfa drug reaction.

Ex: Sulfasalazine

Sulfamethoxazole - trimethoprim


Specific drug and their reaction:

1) Monoclonal-anaphylaxis

2)Angiotensin inhibitor- Angioedema

3)Sulfamethoxazole- Maculopapular rash

4)Penicillin- Urticaria, angioedema, and anaphylaxis


Some of the regular access drug for prescribing according to WHO are amikacin, amoxicillin, clindamycin, cefazolin, and ampicillin. Among the various classes of antibiotics (penicillin and cephalosporins), cotrimoxazole and quinolones are the most common causes of antimicrobial allergy. The clinical manifestations of antibiotic allergy may be cutaneous, organ-specific ( e.g. blood dyscrasias, hepatitis), systemic( anaphylaxis, hypersensitivity). The identification of drug allergy is identified by the putative drug history and patient education. selection of proper antimicrobial is very important for good patient outcomes decreased resistance and effective treatment.




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Nishi Sheth

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