Oral Testing of Reported Penicillin Allergies?

Penicillin is miraculous.  It was discovered in 1928 by Alexander Fleming (founding the modern era of antibiotic medicine) and is still the most common antibiotic prescribed in my jails.  The dentist and I use Penicillin VK as our preferred initial agent for dental infections.  I prescribe PCN VK, as well, for strep throats.  I use amoxicillin occasionally for sinus infections and UTIs and even amoxicillin/clavulanate (Augmentin) occasionally. 

Because penicillin is so useful (and inexpensive), I hate to hear the words “I’m allergic to penicillin.” If a patient with a dental infection can’t take penicillin, for example, the dentist commonly prescribes clindamycin, which is expensive, a pain to administer three times a day and has potentially bad side effects.  I have seen more than one patient who developed C. difficile after getting a broad-spectrum antibiotic because of a reported penicillin allergy–probably unnecessarily!

This problem is pretty common since about 10% of the adult population will report a penicillin allergy.  However, research has shown that, when tested, more than 90-95% of patients who state that they have a penicillin allergy really do not. These patients can be harmed by giving them an inferior antibiotic more likely to cause them harm than plain old penicillin.

The test most commonly used to gauge true allergic status is Penicillin Skin Testing (PST). No jail or prison that I know of does skin prick tests.  We also don’t refer patients reporting penicillin allergy to an allergist for testing.  We just groan and prescribe an inferior antibiotic. 

However, this could potentially change based on research published this year on the safety and efficacy of “Direct Challenge” penicillin allergy testing.  Direct challenge means giving a low-risk (this is important) patient an oral dose of whatever penicillin you want to prescribe and observing them for an hour for an allergic reaction. This has been done in studies and has been reported to be safe and effective.

Comparing Direct Challenge of Penicillin Skin Testing for the Outpatient evaluation of Penicillin Allergy: A Randomized Controlled Trial was published this year and can be found here.  These researchers randomized 159 patients with a low-risk history of penicillin allergy to either skin testing (ST) or Direct Challenge (DC) and then observed them for about an hour.  The results showed that “DC was negative in 76 of 79 (96.2%) patients.”  Equally important (in my book anyway) was that all three positive reactions were minor.  Their conclusion: “In low-risk patients, DC provided a safe and effective alternative to PST in delabelling penicillin allergy.  Compared with PST, DC may also take less time, cost less money and lead to fewer penicillin allergy evaluations with false-positive results.”  What’s not to like about that?

Here’s another:  Direct oral amoxicillin challenge without preliminary skin testing in adult patients with allergy and at low risk with reported penicillin allergy, found here.  These researchers concluded: “This study added to the accumulating body of evidence that supports the safety and efficacy of direct provocative challenge without preliminary skin testing to exclude penicillin allergy in individuals at low risk.”

Evaluating Penicillin Allergies Without Skin Testing (here) concludes “Direct oral amoxicillin challenges in low-risk individuals are well accepted by patients and a safe and effective part of penicillin allergy delabelling.”

Finally, Evaluation and Management of Penicillin Allergy: A Review, was published in JAMA this year (here) and says “Direct amoxicillin challenge is appropriate for patients with low-risk allergy histories.”  Also, “Evaluation of penicillin allergy before deciding not to use penicillin or other Beta-lactam antibiotics is an important tool for antimicrobial stewardship.”

If you decide to do a Direct Penicillin Challenge in your facility, I highly recommend downloading and reading the JAMA article in its entirety. The most important aspect emphasized by all of these articles is that the patients must be low-risk. According to JAMA. low-risk patients are those who report non-typical allergic symptoms, such as GI upset, itching without rash, or unknown reactions that occurred greater than ten years ago (e.g. “My Mom told me I was allergic.”).  You then must obtain informed consent and then monitor the patient after administering the penicillin for about an hour in your medical area (they should not be sent back to their dorms). You need to be able to treat an anaphylactic reaction, should one occur.

As always, what I have written is my opinion, based on my training, experience and research.  I could be wrong!  If you think that I am wrong, please say why in comments!

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One thought on “Oral Testing of Reported Penicillin Allergies?

  1. AvatarBertram Moshier

    Hello,

    I agree with your direction. As for myself, I have a Suffa / Surfer allergy based upon breaking out all over my body with itching 2 days after I finished a course of Suffa antibiotic. This was 20 years ago this year and no doctor has wanted to try again after suggesting it.

    I am still wondering if it was a fluke or is it a serious allergy. The doctors say why risk it given there are alternatives. Guess they are right, but suffa drugs are the first line for certain infections and to eliminate them, just as in your article seems ashame.

    Thank you.

    Reply

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