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Introduction: Beta-lactam antibiotics are the most frequent cause of antibiotic hypersensitivity reactions. The study of all cases of suspected beta-lactam hypersensitivity is highly important, to avoid the use of less efficient or more expensive alternatives, for fear of a reaction., Materials and Methods: Sixty-seven consecutive patients with suspected beta-lactam hypersensitivity reactions were studied. Skin prick tests (SPT), intradermal tests (IDT) and specific IgE determination were performed. In non-immediate reactions, epicutaneous testing was also done. If all were negative, a drug challenge was performed., Results: Sixty-seven patients (54 female symbol), with a mean age + or - SD of 36.6 + or -19.3 years (4-78 years) were studied. The self-reported antibiotics were amoxicillin and amoxicillin/clavulanic acid in 30 (45%), penicillin in 24 (36%), cephalosporins in 11 (16%) and flucloxacillin in 2 (3%). SPT and IDT were positive in 6 patients (9%) and specific IgE in 11 (16%). Only one patient had both positive specific IgE and skin tests. Of the remaining 51 cases, 33 underwent a drug challenge with the culprit antibiotic, with a positive reaction in 2 (6%). In all positive cases and when a drug challenge with the suspected antibiotic was not indicated, a challenge with an alternative drug was done, all with negative results., Conclusions: Of the 67 studied cases with history of beta-lactam hypersensitivity reactions, 18 (27%) were confirmed after testing. A combination of skin testing, specific IgE determination and drug challenge is necessary since none has sufficient sensitivity to be used alone.

Methylphenidate is the treatment of choice in attention-deficit/hyperactivity disorder (ADHD). The authors report the case of a 7 year old boy with ADHD and psoriasis who developed generalised erythema, pruritus and fever 5 hours after the first oral administration of methylphenidate. After 2 days of treatment the drug was discontinued with complete resolution of symptoms. Later on, the drug was re-introduced with recurrence of the same clinical symptoms. Patch tests were performed with negative results. Desensitization was proposed and performed because there is no alternative treatment for ADHD. After the therapeutic dose was achieved, the mother interrupted drug intake because of a misunderstanding of instructions, and a mild rash subsided when another pill was administered. After this event the same desensitization procedure was carefully repeated. Interruption of drug intake during desensitization and consequent recurrence of clinical symptoms highlights the importance of continued exposure to the culprit drug in this kind of procedure. This modified protocol may enable patients with cutaneous reactions to this drug, to maintain therapy without recurrent reactions.

Allergic reactions to midriatic eyedrops are rare despite extensively used by ophthalmologists. Phenylephrine is responsible for 54-95% of cases reported in literature. We present the case of a 56-year-old man with blepharoconjunctivitis after instillation of phenylephrine 5%, tropicamide 0.5%, oxibuprocaine eyedrops. The patient reported good tolerance to the mentioned drugs. Immediate readings of prick and intradermal tests, performed with the suspected drugs, were negative. Late readings (48 and 72 hours) of epicutaneous tests were also negative. At 72 hours, prick and intradermal tests to phenylephrine were positive. Allergic blepharoconjunctivitis to phenylephrine was diagnosed. Phenylephrine is an extensively used midriatic that can act as a potent sensitizing agent and can be the cause of allergic contact reactions in exposed patients. With this case we illustrate the relevance of late readings of intradermal tests in the diagnosis of late hypersensitivity drug reactions. The authors discuss about possible mechanisms responsible for negative results of epicutaneous tests.

Background: Corticosteroids (CS) are widely used in the treatment of asthma, allergic disorders and other immunological diseases due to their anti-inflammatory and immunosuppressive properties. Physicians seldom suspect them of causing allergic reactions. However, more and more cases of hypersensitivity reactions to CS have been described. Reports of delayed allergic reactions to CS in patients with asthma or allergic rhinitis are scarce., Material and Methods: We report the case of a 44-year-old woman with a history of mild persistent asthma and intermittent allergic rhinitis, treated with inhaled beclomethasone and salbutamol, who developed a delayed mucocutaneous and respiratory reaction after substitution of beclomethasone with budesonide., Conclusions: The interest of this case lies in the rarity of allergic reactions from inhaled CS in patients with asthma and/or rhinitis. These reactions therefore represent a diagnostic and therapeutic challenge.

Background: Nimesulide is a cyclooxygenase (COX) inhibitor with a high degree of selectivity to COX-2. It is a widely used and well tolerated nonsteroidal antiinflammatory drug that also has analgesic and antipyretic properties. The most frequently reported side effects concern the gastrointestinal tract. Pruritus and skin rash are the most common cutaneous adverse reactions. There are only eight cases of fixed drug eruptions due to nimesulide, described in the literature., Case Report: The authors report a case of a patient with a history of antihistamine hypersensitivity who developed a bullous form of pigmented fixed drug eruption after nimesulide ingestion. Patch tests performed on residual skin lesion were positive to nimesulide, confirming that this was the culprit drug., Conclusions: Fixed drug eruptions are common cutaneous drug reactions, often misdiagnosed. A detailed anamnesis and physical examination are the key to suspect this condition.

Cockroaches have been increasingly recognized as an important source of indoor allergens. In this study we assessed the prevalence of cockroach sensitization among an outpatient population observed at our Department (155 patients with a mean age of 29 +/- 12 years), based on skin "prick" tests with four commercial cockroach extracts along with a common battery of standardized inhalant allergens. We found a positive wheal to at least one of these four extracts in 27 patients: 26 (96.2%) to Blatta orientalis, 10 (37%) both to Blatella germanica and 1 (3.7%) exclusively to Blatella germanica, with no significant concordance between them. We also observed in patients with cockroach positive skin "prick" test an association with atopy (p < 0.001) and with cutaneous reactivity to other indoor allergens, namely house dust mites (p = 0.02), danders (p = 0.01) and fungi (p = 0.01). These data confirm the higher risk of cockroach sensitization among the atopic population sensitized to indoor allergens. However, the heterogeneity of the positive cutaneous responses obtained in this study, possibly reflecting the incomplete standardization of cockroach extracts, questions the real prevalence and clinical significance of this particular sensitization.

Absolute T and B lymphocytes, assayed by E and EAC rosette techniques, serum IgE levels, total eosinophil counts and delayed hypersensitivity cutaneous reactions were studied in 39 asthmatic subjects (19 extrinsic asthmas and 20 intrinsic asthmas) and in 15 age-matched control subjects. The mean value of T lymphocytes was 1753 +/- 709 mm.3 in the extrinsic group, 1511 +/- +/- 530 mm.3 in the intrinsic, and 1609 +/- 451 mm.3 in the controls. There was no statistical difference between the two groups of patients and the controls (P > 0.05). There was also no statistical difference of B lymphocytes between the two groups of patients and the controls. Serum IgE was elevated in 8 extrinsic asthmatics (42.1%), in one intrinsic (5%), and in none of the control population. The mean value of eosinophils ws significantly higher (P < 0.01) in the extrinsic group as compared to the controls. The same was true of the intrinsic group, but not so significantly (P congruent to 0.02). No correlation was observed between the number of T lymphocytes and the skin tests, serum IgE and total eosinophil counts.