Penicillin allergic patients and surgical prophylaxis NEW APPROACH

Penicillin allergic patients and surgical prophylaxis NEW APPROACH TO CEFAZOLIN

IS CHANGING TO “Cefazolin can be safely administered to patients with history of allergy to penicillins including anaphylaxis, EXCEPT in those with severe delayed skin reactions – e. g. Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS. ” If Ce. FAZolin allergic:

Objectives • Explain differences between beta-lactams • Explain cross reactivity – For specific types of beta-lactam • Explain the new approach to surgical prophylaxis

Beta-lactam Ring

Cephalosporin Penicillin Four different Classes of Beta-lactam All Unique Central Structure Carbapenem (e. g. meropenem) Monobactam

Cephalosporin Penicillin Side Chains make the difference within the classes and are responsible for most allergic reactions Carbapenem (e. g. meropenem) Monobactam

So Reactions aren’t about Classes Cephalosporins Penicillins Similar C-7 Position Side Chain – Cross Reactivity Possible Within Group Similar C-3 Position Side Chain – Cross Reactivity Possible Within Group 1 Penicillin G Group 2 Amoxicillin Ampicillin Group 3 N/A Group 1 N/A Group 2 N/A Group 3 N/A Cefoxitin Cephalothin Cefaclor Cefadroxil Cefprozil Cephalexin Cefotaxime Ceftizoxime Ceftriaxone Cefepime Cefadroxil Cephalexin Cefotaxime Cephalothin Cefuroxime Cefoxitin Note that Cefazolin is not here: It has unique side chains that are not found in any other beta -lactams

General Population Of 1000 people reporting a penicillin allergy Only 100 will have their allergy confirmed The real occurrence of allergy in children is lower at around 6% (or 60 in 1000 with a reported allergy). Most reactions are minor such as mild delayed rashes Of the 100 people with a true allergy to penicillin there is a low likelihood of reaction to another beta-lactam Infographics taken from INESSS “Outil D’aide à la Décision en cas D’allergy aux pénicillines`, Juin 2017

Similar Cephalosporins 10 -15 people might react if given a cephalosporin that shares structural similarity with the involved penicillin Different Cephalosporins 1 -2 people might react if given a cephalosporin that does not shares structural similarity with the involved penicillin Carbapenems Less than 1 person is likely to react to a carbapenem Infographics taken from INESSS “Outil D’aide à la Décision en cas D’allergy aux pénicillines`, Juin 2017

What is the math? • If my patient is labelled as penicillin allergic: • 10% chance patient is actually allergic • 1% chance of reaction if given cephalosporin with a similar side chain • 0. 1% chance (1/1000) of reaction if given cefazolin

Why so many wrong allergies on profile? • After 10 years, 80% of people lose allergy • Older drugs weren’t pure – Many had contaminants • Hard to know what is allergy and what isn’t if rash present • Many drugs are often given together, unable to tell which drug caused reaction

Beta-Lactams are Better Use of alternatives antibiotics results in: • Worse efficacy – 2 -7 x more infections • Increased toxicity – 2 x time the readmission rate – 3 x times the C. diff and kidney injury rate • Slower OR flow-through – E. g. Vancomycin takes longer to infuse • ? Increased resistance

What About Severe Reactions? • Anaphylaxis is the most predictable reaction – Anaphylaxis to penicillin is NOT a contraindication to cefazolin • Delayed mild rashes may occur (not a true allergy) – The benefits of beta-lactams outweighs the risk • Severe delayed reactions are poorly understood – Stevens-Johnson, Toxic Epidermal Necrolysis

How do I know? • Signs of severe delayed infection: – Reaction was more than 72 hours after drug started – There were systemic signs of reaction • Fever, hypotension – Skin sloughing – Organs failed (e. g. kidneys, liver) – Patient required hospitalization

How likely are severe reactions? • SJS-TENS occurs in 5 -10/million population • Neutropenia is generally reversible and occurs after several weeks of therapy • Serum sickness is very rare and usually occurs after multiple doses of medication

If this is such a great idea. . . Why isn’t everybody doing it?

They are: 6 Provinces have adopted guidelines

Summary • Ce. FAZolin is safe with almost all penicillin allergies • Severe delayed reactions excluded (for now) • We are starting education in the OR because – It’s where we use the most ce. FAZolin – It supports OR flow-through – This reduces adverse events and surgical infections • We are making sure this is safe moving forward