Penicillins allergy skin testing

TABLE 16.6 Comparison of Allergy History with Penicillin Skin Test Results ... 

Sogn DD, Evans R III, Shepherd GM, Casale TB, Condemi J, Greenberger PA et al. Results of the National Institute of Allergy and Infections Diseases 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. 

Simple patch skin testing is naturally most useful in diagnosing contact dermatitis, but it is unreliable for other allergies. Skin prick tests are helpful in specialist hands for diagnosing IgE-dependent drug reactions, notably due to penicillin, cephalosporins, muscle relaxants, thiopental, streptokinase, cis-platin, insulin and latex. They can cause anaphylactic shock. False positive results occur. 

Green GR, Rosenblum AH, Sweet LC. Evaluation of penicillin hypersensitivity value of clinical history and skin testing with penicilloyl-polylysine and penicillin G. A cooperative prospective study of the penicillin study group of the American Academy of Allergy. J Allergy Clin Immunol 1977 60(6) 339-45. 

There was a high degree of cross-reactivity between imipenem determinants, analogous to the penicillin determinants in penicillin-allergic patients. Nine of twenty patients with positive penicillin skin tests had positive skin reactions to analogous imipenem determinants (40). In view of this appreciable cross-reactivity, imipenem should not be given to patients with penicillin allergy. 

Neither in vitro tests nor skin tests reliably predict cephalosporin allergy (166). The true frequency of allergic reactions in penicillin-allergic patients exposed to cephalosporins has been estimated to be 1 or 2% (167). Nevertheless, when there is a history of penicillin anaphylaxis or other severe IgE-mediated reactions, it is wise to avoid cephalosporins. 

Solley GO, Gleich GJ, Van Dellen RG. Penicillin allergy clinical experience with a battery of skin-test reagents. J Allergy Qin Immunol 1982 69(2) 238-44. 

Negligible cross-reactivity has been reported in both animal and human studies involving hapten inhibition, skin tests, and treatment of penicillin-allergic patients with therapeutic doses of aztreonam (12,14-19). Aztreonam therefore seems to be a safe alternative for patients with penicillin allergy. However, the numbers of safely treated patients reported are still small, and immediate type hypersensitivity to aztreonam has been reported in patients with penicillin allergy (20-23). 

Mechanisms of non-immediate reactions are unclear but may be immunological and non-immunological. Delayed reactions of the IgE type are known (131). Aminopenicillins seem to be an important cause of non-immediate reactions (132-134). The morbilliform rash that begins 1-10 days after amoxicillin can be caused by a delayed cell-mediated immune reaction (135) as can fixed drug eruptions (136,137), toxic epidermal necrolysis (138-140), bullous erythroderma (141), and contact eczema (142). Investigation of these disorders should include delayed readings of skin tests (135). In patients with chronic urticaria, penicillin allergy was demonstrated by cutaneous tests. 

Skin tests are first applied as a prick test for safety. In the absence of a local or systemic reaction, an intradermal test is performed and interpreted as described elsewhere (181,182). Experience with skin testing in penicillin allergy has been reviewed (176,183). Properly performed sequential testing is considered a safe procedure, and only an estimated 1% or less of penicillin allergic patients will have systemic symptoms while undergoing skin tests. However, at least three deaths have been reported with both epicutaneous and intradermal testing (184). 

Patients with a history of penicillin allergy should undergo skin testing with both peniciUoyl-polylysine and minor determinant mixtures. Patients with positive skin tests should be treated with another immunologically unrelated compound or should undergo desensitization. The management of patients with a negative skin test but a history of a severe IgE-mediated reaction has to be individualized options include the use of an alternative compound, desensitization, or the controlled administration of a test dose. 

Macy E, Richter PK, Falkoff R, Zeiger R. Skin testing with penicUloate and penilloate prepared by an improved method amoxicillin oral challenge in patients with negative skin test responses to penicillin reagents. J Allergy ain Immunol 1997 100(5) 586-91. 

Ressler C, Mendelson LM. Skin test for diagnosis of penicillin allergy—current status. Ann Allergy 1987 59(3) 167-70. 

One of the most helpful tests to evaluate risk of penicillin allergy is the skin test. Skin testing can demonstrate the presence of penicillin-specific IgE and predict a relatively high risk of immediate hypersensitivity reactions. Skin testing does not predict the risk of delayed or most dermatologic reactions. 

In peniciUin-aUergic patients, oral or parenteral clindamycin may be used. Alternatively, a first-generation cephalosporin, such as cefazohn (1-2 g intravenously every 8 hours), may be used cautiously for patients who have not experienced immediate or anaphylactic penicitlin reactions and are negative for a penicillin skin test. In mild cases in which an oral cephalosporin can be nsed, ce-fadroxU 500 mg twice daily or cephalexin 250-500 mg four times daily is recommended. Other oral cephalosporins, such as cefaclor, cefprozil, and cefpodoxime proxetil, are also effective in the treatment of ceUnhtis bnt are considerably more expensive. In severe cases in which cephalosporins cannot be used because of documented methicihin-resistant staphylococci or severe /3-lactam allergies, vancomycin shonld be administered. 

If a patient has a mild, delayed allergy to penicillin, first-generation cephalosporins (such as cefazolin) are effective alternatives, but they should be avoided in patients with a history of immediate-type hypersensitivity reactions to penicillins (see Table 109-6). The potential for a true immediate-type allergy should be assessed carefully, and a penicillin skin test should be conducted before giving antibiotic treatment to any patient claiming an allergy. 

Wong, B. B., Keith, P. K, Waserman, S. (2006 Aug). Clinical history as a predictor of penicillin skin test outcome. Annals of Allergy, Asthma (s Immunology Official Publication of the American College of Allergy, Asthma, (s Immunology, 97(2), 169—174. 

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