Apparently, when I was little I was given tennis Ilyn and had terrible hives. And the pediatricians told my parents that, if I was ever given it again I would die. So my entire life I was told that if I ever took penicillin it would kill me. Over 95% of people labeled as penicillin or allergic or not despite the fears expressed by this patient. And those like her for most people penicillin antibiotics are safe. And effective there is also an optimal treatment for many infections. It's important for individual patients as well as the healthcare system as a whole that these inappropriate diagnoses be removed from the patient’s medical records. So all patients with a penicillin allergy diagnosis should be evaluated the overdiagnosis of a tennis analogy is the subject of a clinical review. This post covers five toolkits from those reviews that are a resource for clinicians interested in performing penicillin allergy testing in their practice.
This post will explain the risk stratification of patients undergoing penicillin allergy testing patient preparation for testing low-risk patients. And management of reactions to oral penicillin challenge including anaphylaxis testing moderate-risk patients. And follow-up management before testing you must first determine your patient's penicillin allergy risk level. Through a thorough history since there are three parts to penicillin allergy testing skin prick intradermal.
And oral challenge identifying a patient has a low moderate or high risk for having a true penicillin allergy will determine what types of testing they'll need the history should include details of the past reaction. If the patient knows any including timing relative to the penicillin dose and what treatment the patient received at the time of the reaction.
Some examples of low-risk patients include the patient who says they're allergic to penicillin but also reports tolerating a course of augmentin prescribed to them at urgent care last year patients like this can be reassured that they're not allergic to penicillin patients who report reactions to penicillin.
That is consistent within tolerance rather than true allergy nausea vomiting diarrhea or headache can also be reassured through a direct amoxicillin challenge that may be needed to provide maximal reassurance to the patient. On the other hand, patients who have experienced severe reactions to penicillin in the past including blistering rash, hemolytic anemia, thrombocytopenia, nephritis, hepatitis, fever, joint pain or anaphylaxis are considered high-risk and should not be tested. But can be considered for a specialist referral to patients with unstable or compromised hemodynamic or respiratory status. Or pregnancy is always considered to be at least moderate risk for having a true penicillin allergy.
Anyone else with a history of a reaction temporarily associated with penicillin should undergo some form of penicillin allergy testing. Once you've determined your patient's risk level you can move on to testing review what medications.
Your patient is currently taking before beginning any part of penicillin allergy testing for higher-risk patients beta-blockers should be held for two days before testing. Because beta-blockade can inhibit the action of epinephrine during anaphylaxis of challenges are routinely performed, inpatients. On beta-blockers, your anaphylaxis kit should include glucagon to overcome beta-blockade. If necessary for skin testing the patient should not have taken an antihistamine in the last five days tricyclic antidepressants. And antipsychotics can have strong antihistamine activity that can last a week or longer after stopping the medication. High doses of immunosuppressants including steroids are most likely to interfere with a delayed response. But also may interfere with skin testing to rule out IgE mediated reactions.
However, you can do a skin test as long as there's a positive histamine response. So you can check a histamine prick test before canceling the test after medication review perform.
A physical exam including vitals inspection of the oral pharynx and uvula. If available establishing a baseline peak flow meter reading confirm that the patient is in their usual state of health contraindications to testing include acute illness.
New medications increased rescue, inhaler use increased oxygen requirement or new chest tightness toolkit. I provide a sample anaphylaxis kit checklist prior to any testing you must have an anaphylaxis kit in the clinical area that has medications needed to rescue.
Someone in the event of an anaphylactic reaction. It should also include IV fluids in an IV start kit check the kit. Before each test to make sure nothing missing or expired any drug. Used should be immediately replaced although all sites should have access to a similar kit.
Keep in mind that anaphylaxis resulting from oral amoxicillin challenge testing is an extremely rare event. If your patient is low risk then they can proceed to the direct oral amoxicillin challenge toolkit B covers the oral amoxicillin challenge for low-risk patients. which is a single 250milligram or 500-milligram dose of amoxicillin followed by observation for a minimum of an hour with vital sign checks every 30 minutes going directly to the oral challenges appropriate for patients? The most common reactions will be subjective symptoms such as itching without a rash scratchy.
Throat or vague gastrointestinal symptoms. These symptoms are often side-effects or results from patient anxiety if a patient complains of any of these check their vital signs and examine them. Looking for objective signs of an allergic reaction and observe for an additional 30 minutes.
If at that point there are no objective symptoms the patient can be reassured that the symptoms were likely not an allergic reaction. ।f there are doubts about symptoms resulting from an oral challenge then consider specialty referral the next most common reactions are mild cutaneous ones that can be treated with antihistamines like Racine. Or effects Afeni Deandiphenhydramine can be used. But will cause drowsiness epinephrine may be used for more diffuse urticaria reactions. And will work more rapidly. Than antihistamines again increase the observation period by 30 minutes.
To make sure there are no signs of a systemic reaction and that the cutaneous reactions subside. These symptoms represent a potential penicillin-allergic response. So the patient should remain labeled as penicillin-allergic and specialty referral may be considered anaphylaxis. Typically involves more than two organ systems look for these cutaneous respiratory cardiovascular and gastrointestinal symptoms low blood pressure alone in the setting of known allergen exposure is also considered anaphylaxis. Again epinephrine can be considered for diffuse urticaria to abort a reaction quickly and avoid progression to anaphylaxis. If a patient is having an anaphylactic reaction get out the anaphylactic kit and open it. Uplay the patient supine and elevate their legs. Check the airway breathing circulation. Give up nephron adjunctive medications and IV fluids and call 911.
Determine to be of moderate risk skin testing is performed before an oral amoxicillin challenge for penicillin allergy skin testing. This is what you'll need these are usually provided in commercially available kits in the U.S. There is one such kit on the market the optimal site for both prick and intradermal skin testing is the volar surface of the forearm. Or extensor surface of the upper arm.
Note any rash irritation or tattoos. You want to avoid these during skin testing use an alcohol swab to clean the skin. Once that's dried use a permanent marker to mark where each reagent will be placed. Because most negative skin tests are going to be completely invisible. The markings help you remember where you put the skin test we use a plus to indicate the histamine control. And a minus to mark the Saline negative control. We use PHP to indicate pre pen or the major antigenic determinant of the placement. It doesn’t matter though it's best to place the histamine furthest from the major determinant. Because the flare can bleed into the next test.
If a patient has a very strong reaction to the histamine take the applicator from the reagents then place the applicator on clean dry intact skin. You need to apply a little bit of pressure to break the epidermis. A small drop of the reagent is going to sit on top of the skin and be absorbed through the small punctum. You've created repeat with the other reagents set a timer for 15 to 20 minutes. Before interpreting the results the test is interpreted by comparing the reaction to the major determinant with the reactions to histamine. And sailing controls begin by blotting off extra reagents from the skin. Measure the size of the wheel and the flare across the widest diameter at each site there are different acceptable criteria for determining a positive test. One is a wheel larger than five millimeters as long as the flare is larger than the wheel. Another is a wheel larger than three millimeters with a change. In the baseline erythema of the flare larger than five millimeters. This histamine site is about four millimeters across the widest diameter of the wheel. And about 42 millimeters across the widest diameter of the flare. So this is positive as expected this saline control is negative as expected. And at the major determinant site, you see a 5-millimeter Wheeland a 31-millimeter flare. So this skin prick test is positive which is rarely seen the application of topical diphenhydramine or hydrocortisone to the positive histamine control and other positive tests is rarely needed but can be used to relieve short-lived symptoms. The histamine test should be clearly a positive common reason for a negative histamine test. Include inappropriate placement of the test or inhibition by medications often antihistamines. And chronically ill patients may not respond appropriately.
Positive sailing include Dermott agraphia and chronic urticaria. The Saline controls should be clearly negative is common reasons for a positive sailing include Dermott agraphia and chronic urticaria. The next step after negative skin testing intradermal testing. Before proceeding to the final step the oral amoxicillin challenge each step increases the negative predictive value of penicillin allergy testing. The skin preparation and placement of the markings are the same except you don't have to place an intradermal histamine control for intradermal testing. Onle sterile reagents and vials are used drawn up into tuberculin syringes the technique is similar to that used for placing a PPD injection amount of reagent approximately 0.02milliliters. Just below the epidermis to raise a tiny blip after placing the blabs wait for 15 to 20minutes and interpret the results. Using the same criteria as the skin prick test skin testing is completed wipe the area down with an alcohol swab. You can apply topical diphenhydramine or hydrocortisone to relieve itching from a positive test.
Here we have an example of a negative skin prick test on the left arm followed by a negative intradermal test on the patient's right arm. This is far more common sight than the positive test demonstrated earlier. If intradermal testing is negative you can proceed to the oral amoxicillin challenge which is the same as the direct oral amoxicillin challenge for low-risk patients. If a patient reacts during either skin test do not proceed with an oral challenge and consider specialty referral most patients. Don't complain of pain from the skin Creekfest applicators or the small needles used for intradermal testing. Though almost everyone will have itching at the site of the histamine test occasionally bruising seen in patients on antiplatelet drugs or anticoagulants. But this is easy to distinguish from a positive test. Fewer than five and a hundred people undergoing penicillin allergy testing will have a reaction. These are usually the mild skin reactions that can be managed with antihistamine medications as outlined earlier. In this post again anaphylaxis during penicillin allergy testing is extremely rare once testing is complete the patient's chart needs to be clearly and thoroughly updated.
If testing is negative removing a label of penicillin allergy can be difficult first edit the penicillin allergy entry in the allergy record adding details of the thorough allergy history. You took prior to testing use the free text box. Most DMR's will have to document the test date and the result. Then delete the allergy from the record some EMRs will require a reason to delete analogy. Something like the resolution of allergy is appropriate second provides for the patient to share with other clinicians and pharmacists. Ideally, your clinic will take the time to communicate directly with the patient's pharmacy. If you're not the patient's primary care clinician the results also need to be communicated directly to the primary care clinician. Finally, communicate to the patient that they should call you if they develop new symptoms like itch or rash in the next 24 hours. Or if the site of a skin test turns hard and itchy a negative test consisting of negative skin testing. And a minimum of one hour of observation.
After an oral challenge means that the patient does not have a risk of an immediate reaction. But the risk of a delayed reaction at the population level is between two and five percent. If a delayed reaction develops either at the site of skin testing or rash this should be clearly documented ideally including a photograph. And specialty referral considered if testing is positive again. You'll need to first edit the penicillin allergy record in the EMR adding the details about the patient's allergy history that you've elicited and added the test date and results. That demonstrates allergy whether it's a positive skin test or a reaction to an oral challenge specify the subjective and objective. Findings of the reaction second provide the patient with the documentation for their outside clinicians and pharmacy again ideally you'll communicate directly with the patient's pharmacy. And primary care clinician third lets the patient know that positive tests can wane over time.
Avoid all penicillins cephalosporins and carbapenems
So that retesting in five years should be considered finally instruct the patient to avoid all penicillins cephalosporins and carbapenems until they undergo further evaluation specialists.
If deemed appropriate the need for specialty care can be based on the patient's specific health needs some additional considerations tolerance of a cephalosporin or other beta-lactam in a patient labeled. Penicillin allergy doesn't rule out penicillin allergy tolerance of penicillin in a patient with a history of cephalosporin allergy does not rule out a cephalosporin allergy. This is because cross-reactivity between different beta-lactams can occur based on shared my chains in the setting of positive penicillin skin testing consider specialty consultation for further testing to assess for cross-reactivity.
Between penicillin and other beta-lactams or if a patient has a history of cephalosporin allergy and negative penicillin skin testing and amoxicillin challenge consider specialty referral for further testing. To address the cephalosporin allergy patients with a history of reacting to augmentin may have reacted to the Clavel innate component rather than amoxicillin.
So negative penicillin skin testing and oral amoxicillin challenge do not exclude augmentin allergy in these patients. A specialist can test for sensitivity to Clavel innate. Finally, the information provided in this post is applicable to adult populations.
In the U.S. there are extra considerations when testing kids hospitalized patients and pregnant women. So these patients should be evaluated by specialists given a large burden of inaccurate. Penicillin allergy diagnosis clinician who starts allergy testing in their practice will be helping their own patients. Should those patients need penicillin therapy in the future and also be contributing to the population level reducing costs and minimizing a major contributing factor in the antimicrobial resistance crisis.