This current study found that among patients with a label of beta-lactam allergy there was a low rate of true allergy observed. The overall rate of false positive reports of penicillin allergy was high with 96.1% of patients with a prior history of beta-lactam allergy advised that they could safely re-introduce beta-lactam antibiotics. The rate of true penicillin allergy in this sample was much lower than in other studies of referral populations, which have documented 10–20% true allergy among patients labeled as beta-lactam allergic [1–3]. Consistent evaluation of patients with a history of beta-lactam allergy could reduce the use of broad-spectrum antibiotics if performed before labelling patients with a presumed allergy. This practice could significantly reduce the risk of patients receiving broad spectrum antibiotics inappropriately, which is thought to contribute to antibiotic resistance. The Centers for Disease Control and Prevention report that in the United States there are about 2 million illnesses and 23,000 deaths caused by antibiotic-resistant bacteria . The AAAAI has urged more aggressive use of drug allergy testing to reduce increasing rates of antibiotic resistance .
Previous studies have reported that 9–11% of patients have systemic reactions when skin testing is performed to beta-lactams [17, 18]. In a recent study 2.6% of beta-lactam allergic children reported mild to moderate reactions to skin testing . Our study, in contrast, noted no systemic reactions to skin testing (although several possible explanations could exist for this finding).
In the current study, no patient with negative intradermal testing had a subsequent anaphylactic reaction on oral challenge. One patient had emesis and abdominal pain, which was considered to be potentially indicative of a type I reaction as it was shortly following oral challenge in a toddler. In addition, 1.3% (4 patients) had a delayed reaction on oral challenge, despite negative intradermal testing.
A possible limitation of our study was the lack of delayed intradermal readings and use of patch testing. For delayed beta-lactam reactions, some studies have suggested that either or both of these methods may provide some value [20–22]. In fact, some clinical management reviews recommend delayed intradermal testing and/or atopy patch testing in the evaluation of non-immediate reactions to penicillins . Recent studies have also used 5-day drug provocation testing to evaluate non-immediate reactions to amoxicillin .
Our study followed the AAAAI practice parameter which recommends avoidance of testing and oral challenges in patients with a history of severe cutaneous adverse drug reaction such as serum sickness or Stevens Johnsons. Interestingly, other studies have noted a low correlation between reaction history for severe adverse drug reactions and subsequent risk of reactivity .
Low consensus between confirmed beta-lactam allergy and documented history of a beta-lactam allergy has implications for the implementation of a national agenda around interoperable digital patient health records among health care settings . Interoperability is proposed to improve patient care and outcomes  but could present problems if erroneous clinical information is being shared due to the lack of patient record accuracy. Health care providers and administrators should be aware of the risk of sharing potentially erroneous patient data. These findings suggest the need to more actively incorporate strategies into primary care practices to proactively identify patients who are likely mislabeled with beta-lactam allergy to avoid the harms of antibiotic avoidance.
This study tracked consultation recommendations as oppose to more objective test results which was expected to produce a more reliable measure of the effects of penicillin allergy consultation in determining rates of valid avoidance of beta-lactams. Assessing the practices of only two physicians operating within one clinic can create the potential for bias related to clinical decision making. Our sample is primarily pediatric patients and it may not apply to other populations without assessment of local prevalence and demographics of ‘penicillin allergy’. Furthermore, this sample is dependent on the referral of primary care physicians so it is uncertain if certain patient populations with greater or lesser risk of mislabeling are being referred or not.