Penicillin G is safe, reliable for testing children with history of penicillin allergy

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Children with a history of penicillin allergy can be safely and reliably skin tested with only penicillin G, new research suggests.

This approach could be a useful alternative to penicilloyl-polylysine (PPL), which has been commercially unavailable for most of the last decade, making penicillin allergy testing difficult, the authors write.

Dr. Jennifer A. Lowry of Children's Mercy Hospital and the University of Missouri-Kansas City (UMKC) School of Medicine told Reuters Health by email, "Allergy testing can be completed by obtaining an accurate history, and using the medication as a skin test is effective if suggestive of an IgE-mediated or immune related response. Also, rechallenging based on history and response to skin testing can accurately determine true allergies."

"Often, rashes (especially delayed with antibiotic uses) are not caused by the drug, but by the disease itself (most often viral illnesses). Additionally, we know that 90% of patients who believe they are allergic to penicillin are not. Thus, using an easier skin testing procedure with a graded challenge may help practitioners determine more readily if their patients truly cannot receive penicillin," she said.

But Dr. Lowry, who was not involved in the new study, cautioned, "Only providers with training should test children with penicillin G, and offices should be prepared to treat anaphylaxis emergently. While patients who have a history of anaphylaxis do not require skin testing - as the history should be enough to continue the allergy on the medical record - others may have anaphylaxis with skin testing."

To determine the safety and negative predictive value (NPV) of skin testing without PPL, using only penicillin G, lead author Dr. Matthieu Picard of Centre Hospitalier Universitaire Sainte-Justine of the Universite de Montreal in Quebec, Canada and colleagues studied children evaluated for a history of penicillin allergy at their clinic over three years.

They gave each child a skin test with only penicillin G and, if the skin test result was negative, followed up with a three-dose graded challenge to the culprit penicillin.

Among 563 children skin tested to penicillin G, 185 (33%) tested positive. These children had a shorter interval between the initial reaction and skin testing compared with children who had a negative skin test result (P=0.03). Overall, 375 of 378 patients with a negative skin test result were challenged and 18 (4.8%) reacted, giving a NPV of 95.2%.

Of the 17 children with a history of anaphylaxis and a negative skin test result, three reacted to the challenge (NPV, 82.4%). All challenge reactions were mild and resolved quickly with treatment, the authors report in their study online May 22 in the Annals of Allergy, Asthma and Immunology.

Dr. Jennifer L. Goldman, also of Children's Mercy Hospital and UMKC and also not part of the study team, told Reuters Health in an email, "This study highlights the importance of evaluating a method of penicillin skin testing with only penicillin G followed by a graded oral challenge in the absence of commercially available PPL. Evaluation of this method in children is critical to a better understanding of possible alternatives if the standard approach is impeded by lack of availability of the antigenic determinant. These findings offer an important reminder that both skin test and oral graded challenge are critical components of assessing these patients."

"In the era of increasing drug-resistant organisms causing infections in children and a dearth of new antibiotic development, better defining penicillin allergies in patients is critical so that unnecessary use of alternative broad-spectrum antibiotics can be avoided," she advised.

"Penicillins remain the recommended drug of choice for the treatment of many childhood infections including otitis media, strep throat, and community-acquired pneumonia. Penicillin allergy evaluation remains a key component for identifying those children labeled with a penicillin allergy who can safely take the drug and those who should avoid it," she said.

The corresponding author was unable to respond to requests for comments.

SOURCE: http://bit.ly/1pcNKct

Ann Allergy Asthma Immunol 2014.

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