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Allergy to penicillin is reported to occur in up to 8% of the patients who receive this class of drugs. 80 to 85% of the patients with a positive clinical history to penicillin will nevertheless tolerate penicillin with no adverse effect. Of the remaining 15 to 20%, only a few will develop a severe adverse reaction, and these patients can be identified by skin tests with derivatives of penicillin used at optimal concentrations according to a protocol that is effective and safe. Skin tests to penicillin are positive in 25% of patients with a history of an immediate reaction to penicillin; they are more frequently positive in those who have had a severe reaction. In addition to being able to identify patients who are at risk for a severe reaction when they take penicillin, skin tests can also provide immunological evidence of the origin of delayed clinical reactions such as maculopapular rashes. Such rashes, a frequent and benign manifestation of penicillin allergy, are usually caused by the widely used aminopenicillins. Intradermal skin tests (IDR) and late phase (patch) tests can demonstrate allergy to betalactamines in 5 to 45% of patients with negative skin tests to major and minor determinants of penicillin. When skin tests are positive, provocation tests are not recommended. On the other hand, when the skin tests are negative, an oral provocation test should be done, but such tests can result in an immediate clinical reaction, which may be severe in 3 to 10% of cases. [Copyright &y& Elsevier]

We report the case of a 37 years-old nonatopic woman who experienced several anaphylactic reactions after ingesting low doses of the methylmorphine derivatives codeine and codethyline. The IgE mediated mechanism was confirmed by the detection of morphine-specific IgE antibody, determined by radioimmunoassay (RAST). Cross reactivity with codeine was shown by inhibition of the morphine RAST. The gravity of the clinical state not permitting an oral provocation test, we were able to confirm an IgE-mediated mechanism by demonstrating that the anti-morphine IgE did not recognize the quarternary ammonium group. [Copyright &y& Elsevier]

Prick-tests to foods are usually carried out as the first step in the diagnosis of food allergy. Severe anaphylaxis accounts for 4.9 % of allergies in children and occurs more frequently in adults, raising the possibility of systemic reactions to prick-tests in highly sensitized people. Several studies published in the literature have used commercial extracts. As for airborne allergens, concentrations causing a skin reaction of 15 mm do not present a risk of systemic reactions. Prick-tests to native foods--prick-in-prick tests--have been less extensively studied. The CICBAA1 data, from 1,138 food allergic patients of all ages, cover 34,905 prick-in-prick tests to foods. The wheal of these prick-tests has been regulary registered. The risk of systemic reactions can be evaluated at 0.008 %. There were no severe reactions and anti-histamine and corticosteroid therapy were sufficient. These results are similar to those of the large study in 2000 carried out by Devenney in neonates (0.005%). A review of the literature reveals only a few severe reactions in adults. The authors draw attention to the necessary precautions: temporary contra-indication for skin prick-tests in children and adults with grade 3 or 4 asthma, with particular attention to such foods as all kinds of nuts, fish, etc.

The diagnosis of latex allergy is mainly based on prick-tests. In order to improve the efficiency of the diagnosis, a comparative study of three latex materials is carried out in 64 controls and 29 patients allergic to latex = Stallergènes and Allerbio extracts, prepared from crude natural latex, and an ammoniated emulsion of rubber latex (AEL). No adverse reactions are recorded. The specificity is 100% for both extracts, 85% for AEL. Sensitivity is respectively 68%, 63%, 72%. The range of values of the wheal is significantly narrower for Stallergènes extract. 46% of allergic patients are reactive to the three materials. The combined use of three materials reaches an 80% efficiency similar to that of Rast Cap System and the addition of three prick-tests and Rast obtains an efficiency of 93.1%. Using several latex materials could increase the efficiency of the diagnosis, inasmuch as the extracts are generated from natural latex, whereas patients are sensitized to manufactured products originating from ammoniated latex.