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Amoxicillin and antibiotics

Amoxicillin may be the most useful antibiotic to the practicing pediatrician because of its good activity toward Streptococcus pneumoniae, its effectiveness for a wide array of infectious diseases, its low cost and adverse effect profile, and its favorable pharmaceutical profile (good taste of oral suspension and numerous dosage forms). Amoxicillin or ampicillin may result in a unique rash which is not indicative of an IgE-mediated penicillin allergy and which does not require skin testing. This maculopapular rash occurs in approximately 5%-10% of patients given amoxicillin or ampicillin. Upon readministration of amoxicillin or ampicillin, this rash may reoccur, although systemic symptoms rarely occur. For the child who suffers a reaction more indicative of an IgE-mediated reaction, such as an urticarial rash, penicillin skin testing should be utilized.

Many commercially available antibiotics and classes of antibiotics share a common chemical structure, the ß-lactam ring, and these antibiotics are referred to as ß-lactam antibiotics. Penicillin (and the penicillins {eg, piperacillin}), amoxicillin, the cephalosporin class and carbapenem (eg, imipenem, meropenem) antibiotics are all classified as ß-lactam antibiotics, and all share the potential for cross-reactivity in a patient with a history of an IgE-mediated hypersensitivity reaction to penicillin. The cephalosporins are likely the most utilized class of non-penicillin ß-lactam antibiotics prescribed by office-based pediatricians. These cephalosporins include cephalexin (Keflex, Advancis), cefuroxime (Ceftin, GlaxoSmithKline), cefpodoxime (Vantin), cefdinir (Omnicef, Abbott), and ceftriaxone (Rocephin, Roche). The risk of a child, who has reacted positively to penicillin skin testing, suffering an allergic reaction to a cephalosporin antibiotic is quite low – <2%. It is believed that the 1st-generation cephalosporins (eg, cephalexin) are more likely than 2nd-generation (eg, cefuroxime) or 3rd-generation (cefpodoxime) cephalosporins to be cross-reactive. This is due to the chemical similarity of side-chains of the ß-lactam ring between penicillin and 1st-generation cephalosporins. If a child with a history suggestive of an IgE-mediated allergic reaction to penicillin (eg, urticarial rash) requires treatment with a cephalosporin, skin testing for penicillin therapy should be done. If skin testing for penicillin allergy is positive, therapeutic options include avoiding use of cephalosporin antibiotics, or graded challenges or desensitization with a cephalosporin (the latter are best preformed by a clinician trained in allergy-immunology). While the risk of cross-reactivity between the penicillin and cephalosporin class is relatively low, anaphylactic deaths have been documented in penicillin skin test-positive patients who have received cephalosporins. Children with a history of an IgE-mediated allergic reaction to a cephalosporin who require penicillin or amoxicillin should be skin tested for penicillin allergy. In the child with a history of penicillin allergy who has recently safely been treated with a cephalosporin, cephalosporin skin testing is not necessary. Commercially available cephalosporin skin testing reagents are not available, and although protocols for cephalosporin skin testing with diluted cephalosporin antibiotics are available, their use has not been standardized and the negative predictive value is not known.



 


Date: 2015-12-11; view: 910


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