rate of cephalosporins to penicillin because only onereaction occurredwhen this class of antibiotic was given topatients with a history of penicillin and without testing. Isuspect the same patients could have been given penicillinitself with the same safety.

Our experience at The New York Hospital Queensindicates that virtually all such patients can receive pen-icillin safely. For the last 4 years, we have been evaluatingapproximately 100 patients per year with a history ofpenicillin allergywho required a penicillin. All were testedwith penicilloyl polylysine and penicillin G untilSeptember 30, 2004, when the penicilloyl polylysinebecame unavailable in this country. We have seen positiveskin test responses only once or twice a year, and penicillinwas administered to all the patients with negative testresponses without any difficulty. In at least one third ofthe cases, no accurate history was available to evaluatewhether the reaction was originally a severe one. Thusrather than showing a very low cross-reaction rate betweenpenicillin and cephalosporins, I suspect that most of thesepatients were no longer allergic to penicillin.

Stanley R. Fine, MDThe New York Hospital Queens

56-45 Main St

Flushing, NY 11355

REFERENCE

1. Daulat S, Solensky R, Earl HS, Casey W, Gruchalla RS. Safety of

cephalosporin administration to patients with histories of penicillin

allergy. J Allergy Clin Immunol 2004;113:1220-2.

Available online April 5, 2005.doi:10.1016/j.jaci.2005.02.004

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Correspondence 1327

Reply

To the Editor:We appreciate Dr Fine’s1 comments regarding our

study.1a We disagree with his assessment that we ‘‘min-imized’’ the potential allergic cross-reactivity betweenpenicillin and cephalosporins. The retrospective protocolof evaluating cephalosporin reaction rates in patientswith a history of penicillin allergy has inherent limita-tions, which we clearly outlined in discussing ourfindings. One limitation was that inpatient pharmacistsmight have identified some patients with a history ofsevere penicillin allergy, and these individuals wereconsequently denied a prescribed cephalosporin (andtherefore would not be included in our sample of 606patients). The other limitation, as Dr Fine correctly pointsout, is that most of the patients probably lacked penicil-lin-specific IgE antibodies when they were treated withcephalosporins. However, we disagree with his sugges-tion that only 1% or 2% of patients with a history ofpenicillin allergy turn out to have positive penicillin skintest results. Although this might be the experience at hisinstitution, published studies on large groups of patientswith a history of penicillin allergy have reported positive

penicillin skin test result rates ranging from 7.1%2 to63%.3 Most large-scale studies have reported positivepenicillin skin test result rates of between 10% and20%.4-6 Therefore if we assume a conservative estimatethat 10% of the 606 patients (or 61 patients) in our studyhad penicillin allergy at the time of treatment withcephalosporins, only 1 of these 61 patients experienceda mild reaction.

We understand that ideally investigation of potentialallergic cross-reactivity between penicillin and cephalo-sporins requires confirmation of patients’ type 1 penicillinallergy through penicillin skin testing. One of the authors(RS) has reviewed the published medical literature andfound that of 220 patients with positive penicillin skin testresults challenged with various cephalosporins, 9 (4.1%)experienced reactions. It was not the objective of our studyto perform penicillin skin tests. It must also be recognizedthat in the real-world practice of clinical medicine,physicians typically do not refer patients with a historyof penicillin allergy for skin testing and frequently chooseto treat them with cephalosporins.7

In summary, our study found a low rate of reactionsto cephalosporins in a selected group of inpatients withhistories of penicillin allergy. We recognize and statedits limitations, and we look forward to future researchto answer once and for all the question of allergiccross-reactivity between penicillin and cephalosporins.We did not minimize the potential cross-reaction rate be-tween penicillin and cephalosporins, and in fact, we con-cluded our study by stating that ‘‘broad administrationof cephalosporins to patients with a history of penicillinallergy cannot be recommended at this time.’’

Roland Solensky, MDa

Sonak Daulat, MDb

Harry S. Earl, MDb

William Casey, RPhc

Rebecca S. Gruchalla, MD, PhDb

aThe Corvallis ClinicCorvallis, Ore

bUniversity of Texas Southwestern Medical Center

Division of Allergy and Immunology

UT Southwestern Medical Center5323 Harry Hines Blvd

Dallas, TX 75390-8859cParkland Health and Hospital System

Dallas, Tex

REFERENCES

1. Fine SR. Safety of penicillin administration to patients with histories of

penicillin allergy. J Allergy Clin Immunol 2005;115:1326-7.

1a. Daulat S, Solensky R, Earl HS, Casey W, Gruchalla RS. Safety of

cephalosporin administration to patients with histories of penicillin

allergy. J Allergy Clin Immunol 2004;113:1220-2.

2. Gadde J, Spence M, Wheeler B, Adkinson NF Jr. Clinical experience

with penicillin skin testing in a large inner-city STD clinic. JAMA 1993;

270:2456-63.

3. Sullivan TJ, Wedner JH, Shatz GS, Yecies LD, Parker CW. Skin testing

to detect penicillin allergy. J Allergy Clin Immunol 1981;68:171-80.

4. Sogn DD, Evans R, Shepherd GM, Casale T, Condemi J, Greenberger

PA, et al. Results of the National Institute of Allergy and Infectious

J ALLERGY CLIN IMMUNOL

JUNE 2005

1328 Correspondence

Disease collaborative clinical trial to test the predictive value of skin

testing with major and minor penicillin derivatives in hospitalized adults.

Arch Intern Med 1992;152:1025-32.

5. Solley GO, Gleich GJ, Van Dellen, RG. Penicillin allergy: clinical

experience with a battery of skin-test reagents. J Allergy Clin Immunol

1982;69:238-44.

6. Macy E, Richter PK, Falkoff R, Zeiger R. Skin testing with penicilloate

and penilloate prepared by an improved method: amoxicillin oral

challenge in patients with negative skin test responses to penicillin

reagents. J Allergy Clin Immunol 1997;100:586-91.

7. Solensky R, Earl HS, Gruchalla RS. Clinical approach to penicillin allergic

patients—a survey. Ann Allergy Asthma Immunol 2000;84:329-33.

Available online April 14, 2005.doi:10.1016/j.jaci.2005.02.027