I just came off a very busy clinical stretch at my hospital where I also serve as the Medical Director of Antimicrobial Stewardship. I was a bit disappointed in myself because I felt that I was accepting a large number of penicillin allergies at face value resulting in the use of more Carbapenems. Now that the dust has settled clinically (at least for a couple of days), I have had the chance to reflect on this as well as consult the literature in an effort to "mend my ways". Fortunately, Trubiano, Adkinson and Phillips just published an excellent clinical review on Penicillin Allergy in JAMA 2017;318 (1):82-83. They mad some excellent points which I think are important to highlight.
1) 10% of all inpatients will claim to have a penicillin allergy but only 10% of these or 1% of the population will have a true allergy.
2) If a patient has had a true IgE hypersensitivity reaction to penicillin these antibodies are often gone a decade after the reaction.
3) For patients who have a history of a remote and unknown reaction to penicillin the skin test positivity is only 1.7%. There appears little reason to withhold a penicillin agent in this group
3) the cross reactivity of penicillin and cephalosporin reactions is 5% and is low as 2% for third and fourth Generation Cephalosporins (Ceftriaxone, Cefepime). Based on this data there is little reason to withhold these drugs in a patient with a non-serious reaction to Penicillin
4) Late onset rashes occur with Beta-lactams are T cell mediated occur in 2-12%. Patients who have had these reaction do not have a contraindication from receiving a different Beta lactam in the future.
5) Carbapenems and the monobactam Aztreonam have negligible cross reactivity with Penicillin and can be used in the truly Pencillin allergic. It is important to not forget about using Aztreonam when only Gram negative coverage is necessary
It would seem to be optimal to have a Penicillin skin testing service available to sort through these nebulous clinical situations. Unfortunately, many hospitals have neither the reagents or the resources to perform this testing. An alternative strategy is to incorporate a clinical decision support tool into the EMR. A particularly useful tool was used in a study published by authors from Brigham and Women's Hospital (Blumenthal et al. J Allergy Clin Immunol July 2017). Implementation of this computerized guidance and clinical support was associated with a two fold increase in the use of penicillin and cephalosporins.
It is time we get serious about penicillin allergies as part of stewardship. Use of alternative agents is less effective, and associated with increased cost, toxicity and incidence of Clostridium difficile infections.
1) 10% of all inpatients will claim to have a penicillin allergy but only 10% of these or 1% of the population will have a true allergy.
2) If a patient has had a true IgE hypersensitivity reaction to penicillin these antibodies are often gone a decade after the reaction.
3) For patients who have a history of a remote and unknown reaction to penicillin the skin test positivity is only 1.7%. There appears little reason to withhold a penicillin agent in this group
3) the cross reactivity of penicillin and cephalosporin reactions is 5% and is low as 2% for third and fourth Generation Cephalosporins (Ceftriaxone, Cefepime). Based on this data there is little reason to withhold these drugs in a patient with a non-serious reaction to Penicillin
4) Late onset rashes occur with Beta-lactams are T cell mediated occur in 2-12%. Patients who have had these reaction do not have a contraindication from receiving a different Beta lactam in the future.
5) Carbapenems and the monobactam Aztreonam have negligible cross reactivity with Penicillin and can be used in the truly Pencillin allergic. It is important to not forget about using Aztreonam when only Gram negative coverage is necessary
It would seem to be optimal to have a Penicillin skin testing service available to sort through these nebulous clinical situations. Unfortunately, many hospitals have neither the reagents or the resources to perform this testing. An alternative strategy is to incorporate a clinical decision support tool into the EMR. A particularly useful tool was used in a study published by authors from Brigham and Women's Hospital (Blumenthal et al. J Allergy Clin Immunol July 2017). Implementation of this computerized guidance and clinical support was associated with a two fold increase in the use of penicillin and cephalosporins.
It is time we get serious about penicillin allergies as part of stewardship. Use of alternative agents is less effective, and associated with increased cost, toxicity and incidence of Clostridium difficile infections.
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