Increased Adverse Drug Reactions to Cephalosporins in Patients with a Positive Penicillin Skin Test

Abstract

RATIONALE: The American Academy of Pediatrics has endorsed the use of cephalosporins for patients with reported allergies to penicillin (PCN). However, a study of fatal anaphylaxis in England from 1992 to 1997 revealed that 3 of the 6 fatalities were due to cephalosporins in patients known to be allergic to amoxicillin and one to PCN. Hence, caution is still advised if a cephalosporin is to be given in patients with a history of PCN allergy. We conducted a retrospective cohort study comparing the rates of adverse drug reactions (ADR) to cephalosporins in patients with a positive PCN skin test compared to a negative PCN skin test.METHODS: Patients with a history of PCN allergy who underwent PCN skin testing had medical records reviewed for antibiotic administration outcomes. Using the χ2 test, we compared the differences in the proportion of ADR among study patients and historical controls (negative penicillin skin test challenged with a cephalosporin). P value ≤ 0.05 was considered statistically significant.RESULTS: 37 of 125 (30%) patients with a positive PCN skin test received a cephalosporin. 2 of 37 (5%) developed an ADR (rashes) compared to 5 of 675 (0.7%) with a negative PCN skin test (p < 0.01).CONCLUSIONS: Patients with reported PCN allergy and a positive PCN skin test are at a higher risk of an ADR to cephalosporins. PCN skin testing in patients with a reported PCN allergy may be a safe and effective method in stratifying the risk of an ADR before the administration of a cephalosporin. RATIONALE: The American Academy of Pediatrics has endorsed the use of cephalosporins for patients with reported allergies to penicillin (PCN). However, a study of fatal anaphylaxis in England from 1992 to 1997 revealed that 3 of the 6 fatalities were due to cephalosporins in patients known to be allergic to amoxicillin and one to PCN. Hence, caution is still advised if a cephalosporin is to be given in patients with a history of PCN allergy. We conducted a retrospective cohort study comparing the rates of adverse drug reactions (ADR) to cephalosporins in patients with a positive PCN skin test compared to a negative PCN skin test. METHODS: Patients with a history of PCN allergy who underwent PCN skin testing had medical records reviewed for antibiotic administration outcomes. Using the χ2 test, we compared the differences in the proportion of ADR among study patients and historical controls (negative penicillin skin test challenged with a cephalosporin). P value ≤ 0.05 was considered statistically significant. RESULTS: 37 of 125 (30%) patients with a positive PCN skin test received a cephalosporin. 2 of 37 (5%) developed an ADR (rashes) compared to 5 of 675 (0.7%) with a negative PCN skin test (p < 0.01). CONCLUSIONS: Patients with reported PCN allergy and a positive PCN skin test are at a higher risk of an ADR to cephalosporins. PCN skin testing in patients with a reported PCN allergy may be a safe and effective method in stratifying the risk of an ADR before the administration of a cephalosporin.