Selective sensitization to Penicillin V with tolerance to other betalactams.
BACKGROUND
Penicillin G and V have the same betalactam ring. Penicillin V (phenoxymethylpenicillin) results from the substitution of the phenyl acetic acid of benzylpenicillin by the phenoxy methyl side chain.


METHODS
Our patient was a 34-year-old man who experienced generalized urticaria after ingestion of Penicillin V. We performed skin prick tests and intradermal tests with a battery of betalactams including Penicillin V. We also determined specific IgE against penicillin V, penicillin G, amoxicillin, and ampicillin and performed a single-blind oral challenge with Penicillin V, amoxicillin, cefuroxime, and ceftazidime.


RESULTS
The results of skin prick and intradermal tests with the betalactams included were negative. Specific IgE with betalactams was < 0.10 IU/L. The result of a single-blind oral challenge with Penicillin V was positive: 40 minutes after receiving 125 mg of Penicillin V, the patient presented generalized pruritus with hives on his back and chest. He tolerated oral administration of amoxicillin, cefuroxime, and ceftazidime.


CONCLUSIONS
We report an exceptional case of sensitization to Penicillin V with negative results in the allergy workup. Diagnosis was based on a positive single-blind oral challenge result. The patient tolerated other betalactams. We provide a brief summary of the most relevant recent patents.
Leticia
L
Sánchez-Morillas
Patricia
P
Rojas-Pérez-Ezquerra
Rosario
R
González-Mendiola
Prado
P
Gómez-Tembleque
Servicio de Alergia, Hospital Central de la Cruz Roja, Reina Victoria 22, 28003 Madrid, Spain. lsanchezmorillas@hotmail.com.
Julio
J
Laguna-Martínez
D000284:Administration, Oral; D000328:Adult; D000818:Animals; D004342:Drug Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D000939:Epitopes / Q000378:metabolism*; D006801:Humans; D007108:Immune Tolerance; D007114:Immunization; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D010330:Patents as Topic; D010404:Penicillin V / Q000276:immunology / Q000378:metabolism*; D012882:Skin Tests; D014581:Urticaria / Q000175:diagnosis* / Q000276:immunology; D047090:beta-Lactams / Q000276:immunology
D000939:Epitopes; D047090:beta-Lactams; D007073:Immunoglobulin E; D010404:Penicillin V