Published Online: June 14, 2016
Cefazolin, a first generation cephalosporin is often used as pre-operative antibiotic prophylaxis and is known to be a major cause of anaphylaxis. However, correct diagnosis of cefazolin hypersensitivity is not straightforward, mainly because of the lack of in vitro tests and uncertainties concerning the optimal cefazolin concentration for skin testing. Up to now, a maximal non irritating concentration of 2 mg/mL is recommended, although there are reports mentioning higher concentrations to be also non irritating. In the literature, cross-reactivity studies suggest cefazolin hypersensitivity to be a selective hypersensitivity.
In a study recently published in The Journal of Allergy and Clinical Immunology: In Practice, Uyttebroek and colleagues validated the skin test with cefazolin and assessed the drug’s cross reactivity pattern. In this study the team included 66 patients who experienced an anaphylaxis during surgery and were exposed to cefazolin. As a first measure, 20 mg/mL was established as the maximal non irritating concentration for cefazolin. Patients identified as cefazolin allergic underwent skin- and graded challenge testing with alternative beta lactams.
Increasing skin test concentration up to 20 mg/mL allowed the authors to identify an additional 27% of cefazolin allergic patients. All the patients with an IgE-mediated hypersensitivity towards cefazolin displayed negative skin tests for a panel of β-lactam antibiotics (penicillin, cephalosporins, carbapenems and monobactams), and tolerated graded challenges with them.
This study shows that 20 mg/mL is the maximal non irritating concentration that should be used in patients with suspected cefazolin hypersensitivity. Furthermore, the data confirm that cefazolin hypersensitivity seems to be a selective allergy with good tolerance to other β-lactam antibiotics including other cephalosporins.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.