SAN ANTONIO — A penicillin skin test is expected to return to the market in about 1 year to fill the gap that was left when the original manufacturer, Hollister-Stier, halted production of PrePen in September 2003.
The announcement, which was made at the annual meeting of the American Academy of Asthma, Allergy, and Immunology, is good news for patients, physicians, and the health care system in general, said outgoing AAAAI President Michael Schatz, M.D.
Without the availability of a penicillin skin test, physicians have “stepped back 30 years” in managing the 10% of the population who have a history of penicillin allergy, the most frequently reported drug allergy, said Eric Macy, M.D., chair of the AAAAI's Adverse Reactions to Drugs and Biologicals Committee.
The use of penicillin skin testing can rule out a true penicillin allergy in 90% of this at-risk population, allowing such patients to receive penicillin treatment. But since PrePen became unavailable—followed shortly by the disappearance of its European counterpart—physicians have had no alternative but to treat all of these patients with broad-spectrum alternatives, which are more costly and contribute to antibiotic resistance, Dr. Macy said.
AllerQuest, the newly formed company that will manufacture the as-yet-unnamed test, was formed by four AAAAI members. They will partner with Hanford Pharmaceuticals, the leading manufacturer of generic penicillin and antibiotic products in the United States, said Louis Mendelson, M.D., AllerQuest president and CEO.
PrePen was a major determinant for identification of penicillin allergy, meaning that it picked up about 80% of true allergies. Until now, there has been no commercially available minor determinant to pick up the remaining 20% of true penicillin allergy.
However, AllerQuest plans to produce a commercially available minor determinant, “which will extend the diagnostic accuracy for patients,” said Franklin Adkinson Jr., M.D., one of AllerQuest's founding members.
Allergists have been “clamoring” for a penicillin allergy test, Dr. Macy said. “Essentially we have been practicing medicine like we did in 1973,” before the introduction of PrePen, he added.
The consequences of not confirming penicillin allergy—morbidity, mortality, and costs—are often underappreciated by physicians, Roland Solensky, M.D., said in a separate presentation during the meeting.
Studies have shown that unconfirmed “penicillin allergy” accounts for between 31% and 51% of vancomycin prescriptions in hospitals. Such prescriptions can increase the risk of vancomycin-resistant enterococci by fivefold, said Dr. Solensky, of Corvallis, Ore.
At Beth Israel Deaconess Medical Center in Boston, a pilot project to skin test patients for penicillin allergy yielded an 86% rate of negative results and resulted in a significant reduction in the use of vancomycin, quinolones, and clindamycin, he said (Am. J. Med. 1999: 107;166-8).
The study showed that after skin testing, the cost of antibiotics was $106 per patient, whereas before skin testing it had been $209.
Similarly, a recent effort to perform penicillin skin testing at the Mayo Clinic resulted in a reduction in vancomycin use from 30% to 3%.
And at the Cleveland Clinic, penicillin skin testing resulted in changes in therapeutic antibiotic use in 82% of patients, with reductions in the use of vancomycin and quinolones (Infect. Control Hosp. Epidemiol. 2003:24:347-50).