Can I administer Cefazolin (Ancef) and Ceftazidime (Fortaz) in the presence of a Vancomycin allergy?

From the Guidelines

Yes, you can give Ancef (cefazolin) and Fortaz (ceftazidime) to a patient with a vancomycin allergy, as the risk of cross-reactivity is extremely low. According to the Dutch Working Party on Antibiotic Policy (SWAB) guideline for the approach to suspected antibiotic allergy 1, there is no significant cross-reactivity between vancomycin and cephalosporins. The guideline recommends that patients with a suspected immediate-type allergy to cephalosporins can receive penicillins with dissimilar side chains, and cephalosporins with a dissimilar side chain can be used in patients with a suspected immediate-type allergy to a cephalosporin, irrespective of severity and time since the index reaction.

Key points to consider:

• Vancomycin is a glycopeptide antibiotic, and its chemical structure is distinct from cephalosporins, making cross-reactivity rare.
• The patient's allergy history should be confirmed, and the nature of the vancomycin allergy should be documented clearly.
• Monitoring for signs of allergic reaction, such as rash, itching, fever, or respiratory distress, is essential after the first dose of Ancef or Fortaz.
• If the patient has a documented beta-lactam allergy, especially to penicillins, there is a 5-10% cross-reactivity risk with cephalosporins, which may warrant additional caution or consideration of alternative antibiotics.

It is essential to note that the guideline suggests that any carbapenem can be used in patients with suspected immediate-type allergy to a cephalosporin, irrespective of severity or time since the index reaction 1. However, in the context of a vancomycin allergy, the use of Ancef and Fortaz is considered safe, given the low risk of cross-reactivity.

From the FDA Drug Label

Vancomycin solution exhibits a physical incompatibility when mixed with a number of drugs, including ceftazidime. The likelihood of precipitation with ceftazidime is dependent on the concentrations of vancomycin and ceftazidime present It is therefore recommended, when both drugs are to be administered by intermittent IV infusion, that they be given separately, flushing the IV lines (with 1 of the compatible IV fluids) between the administration of these 2 agents.

The answer to the question is no, you should not give Ancef and Fortaz if there is a vancomycin allergy, as the issue is not the allergy itself but rather the physical incompatibility between vancomycin and ceftazidime (Fortaz). However, this incompatibility does not necessarily mean that the patient is allergic to ceftazidime, it is a recommendation for administration.

• Key point: The physical incompatibility is related to the concentrations of vancomycin and ceftazidime, and the recommendation is to administer them separately, flushing the IV lines between administrations 2.

From the Research

Cephalosporins and Penicillin Allergy

• The risk of cross-allergic reactions between penicillins and cephalosporins is lower than previously reported, with an overall cross-reactivity rate of approximately 1% when using first-generation cephalosporins or cephalosporins with similar R1 side chains 3.
• Third- or fourth-generation cephalosporins or cephalosporins with dissimilar side chains than the offending penicillin carry a negligible risk of cross allergy 3, 4.
• Cefprozil, cefuroxime, cefpodoxime, ceftazidime, and ceftriaxone do not increase the risk of an allergic reaction in patients with penicillin allergy 4.

Vancomycin Allergy

• Vancomycin can cause immediate reactions, including non-IgE-mediated reactions (e.g., red man syndrome) and IgE-mediated hypersensitivity (e.g., anaphylaxis) 5, 6.
• Vancomycin infusion reaction (previously called "red man syndrome") is caused by infusion rate-dependent direct mast cell degranulation, and severity can range from flushing and pruritis to angioedema, bronchospasm, and hypotension that mimic type I HSRs 5.
• IgE-mediated HSRs to vancomycin are rare, and vancomycin skin testing yields high false positive rates 5, 6.

Cephalosporins in Patients with Vancomycin Allergy

• There is no direct evidence to suggest that a vancomycin allergy increases the risk of an allergic reaction to cephalosporins such as Ancef (cefazolin) or Fortaz (ceftazidime) 3, 7, 4.
• However, it is essential to note that patients with a history of allergy to one antibiotic may be more likely to have an allergy to another antibiotic, and caution should be exercised when prescribing any antibiotic to a patient with a known allergy 7, 5.