Allergic reactions to common antiinfective drugs.

15 to 20 % of all subjects treated with antibiotics or antiinfective sulpho namides, regardless of age, report reactions suggestive of hypersensitivity to these drugs. The antiinfective agents most frequently involved are beta -lactam antibiotics. It is very important, especially in the case of repeat ed reactions to various antiinfective drugs, to eliminate intolerance or al lergy to concomitant drugs or additives by means of a detailed clinical int erview careful examination of prescribing information of the drugs incrimin ated and, possibly, a challenge or provocation test. Tn the current state o f knowledge, the diagnostic and predictive value of immediate reading skill tests has only been formally demonstrated for beta-lactam antibiotics: the y are essentially indicated in patients presenting symptoms highly suggesti ve of immediate hypersensitivity in whom they confirm or exclude sensitizat ion to beta-lactam antibiotics, and can determine whether the patient is se nsitized to only one or several (classes of) beta-lactam antibiotics, The r esults of recent studies also suggest that immediate reading skin tests to quinolones may present satisfactory sensitivity and specificity. With the e xception of patch-tests (eczema), photopatch-tests and photo-tests after in gestion (photodermatoses), the diagnostic and predictive value of delayed r eading skin tests to antiinfective drugs remains uncertain, and the majorit y of semi-delayed and/or delayed hypersensitivity reactions to these drugs are diagnosed by challenge tests. In general, challenge tests are the only reliable method currently available to confirm or exclude allergy to an ant i-infective drug other than beta-lactam antibiotics, but they are formally contraindicated in patients reporting potentially harmful toxidermia. In th ese patients, it is essential to exclude an infectious cause which, when de tected, excludes the role of the drug.