Drugs-Antibiotics Allergy ======= See also þ Desensitization - [Tidwell BH, Cleary JD, Lorenz KR. Antimicrobial desensitization: a review of published protocols. Hosp Pharm 1997;32(10):1362-1369.] þ PCN allergy - 2-3% of treatment courses - 4-800 anaphylactic reactions per year - [Markowitz M, Lue HC. Allergic reactions in rheumatic fever patients on long-term benzathine penicillin G: the role of skin testing for penicillin allergy. Pediatrics 1996:97(6 Pt 2):981-3.] + 1740 patients on long-term IM benzathine PCN (mean 3.4 years) + 3.2% allergic reactions + 1.23/10,000 injections + 1/32,000 fatal reactions - Reported PCN allergy [Gadde J, Spence M, Wheeler B, Adkinson NF Jr. Clinical experience with penicillin skin testing in a large inner-city STD clinic. JAMA 1993;270:2456-2463.] + Inpatient data: 10% reported allergy to PCN + Only about 10% of THOSE actually have PCN allergy - 20% if hx of anaphylaxis - 776 patients with + hx skin tested - 55/776 (7.1%) had + skin test, 21 had equivocal skin test - 17.3% of those with anaphylaxis had + skin test - 12.4% with hx of urticaria had + skin test - 4% of those with exanthematous rash had + skin test + If negative history for PCN allergy, 2% with + skin test; 4% in another study: [Sogn DD, Evans R 3rd, Shepherd GM, et al. Results of the National Institute of Allergy and Infectious Diseases Collaborative Clinical Trial to test predictive value of skn testing with major and minor penicillin derivatives in hospitalized adults. Arch Intern Med 1992;152(5):1025-32.] + Treatment of skin-tested patients: 93% of history + but skin-test negative got PCN, 3% had acute allergic reaction compared to 0.5% in history - patients; Sogn (see above) found 0.566 with negative skin test had allergic reaction -- never an anaphylactic reaction in skin-test negative patiets in US. þ Cephalosporin-PCN cross-reactivity - The risk of cross-reactivity between penicillin and cephalosporins has been overestimated for second- and third-generation drugs. It is only a significant risk in first-generation cephalosporins that have a similar side chain to penicillin (cephalothin, cephalexin, cefadroxil, and cefazolin). With appropriate monitoring physicians could consider using second- and third-generation cephalosporins in these patients. [Pichichero ME. Cephalosporins can be prescribed safely for penicillin-allergic patients. J Fam Pract 2006; 55:106-12.] - "Patients without a history of an immediate (anaphylaxis) or accelerated (hives, laryngeal edema, bronchospasm, hypotension, angioedema within 72 hours) are no more likely to have a reaction to a cephalosporin than patients with no history of penicillin allergy. This would include patients with the common morbilliform rash. Consequently,k it is not necessary to avoid cephalosporins in these patients." (Mercy Pharmacy Newsletter, June 2002) - Actual cross-reactivity is a percent or less [Suresh AE, Reisman RE. Risk of administering cephalosporin antibiotics to patients with histories of penicillin allergy. Ann Allergy Asthma Immunol 1995;74:167-170; and, Saxon A. Antibiotic choices for the penicillin-allergic patient. Postgrad Med 1987;37:1175-1180]. - Historic 5-15% rate based on flawed study in Postgraduate Medicine, also reportedly from contamination of early cephalosporins with penicillin. - 0/27 PCN-skin-test + patients reacted to cepaholsporin [Solley GO,Gleich GJ, VAn Dellen RG. Penicillin allergy: clinical experience with a battery of skin-test reagents. J Allerg Clin Immunol 1982;69(2):238-244.] - 1/62 PCN-skin-test + patients reacted to cephalosoporin [Saxon A, Beall GN, Rohr AS, Adelman DC. Immediate hypersensitivity reactions to beta-lactam antibiotics. Ann Intern Med 1987;107(2):204-15.] - 2/19 PCN-skin-test + patients with hx of severe PCN allergy reacted to cephamandole; 1 with hypotension and upper airway edema to 20 mg SQ test dose, one with sustained hypotension after 500 mg IM dose - 1/98 (1%) PC-skin-test-positive had reaction to 2nd or 3rd gen cephalosporin. Rate was 6/310 (2%) in skin test negative. [Anne S, Reisman RE. Risk of administering cephalosporin antibiotics to patients with history of penicillin allergy. Ann Allergy Asthma Immun 1989;83:381-385.] þ Monobactams (e.g., Aztreonam) - 0/26 PCN-sensitive patients reacted to aztreonam (Bob Porter, ACEP 2000) þ Carbapenems (e.g., Imipenem) - 50% cross reaction with PCN (Bob Porter, ACEP 2000) - Only a slight increase in reactions if PCN-allergic, and not statistically significant. [Sodhi M, Axtell SS, Callahan J, Shekar R. Is it safe to use carbapenems in patients with a history of allergy to penicillin? J Antimicrob Chemother 2004;54(6):1155-7.] - "The incidence of patients with a reported or documented penicillin allergy experiencing an allergic-type reaction to a carbapenem was 11%, which is 5.2 times greater than the risk in patients who were reportedly not allergic to penicillin" [Prescott WA, Jr., DePestel DD, Ellis JJ, Regal RE. Incidence of carbapenem-associated allergic-type reactions among patients with versus patients without a reported penicillin allergy. Clin Infect Dis 2004;38(8):1102-7.] þ Vancomycin Rash - Vancomycin first dose given too fast; give over 3 hours; often causes "red man" syndrome, more on upper part of body, feels like "hair standing on end"; tell patients about this ahead of time so they aren't frightened. From histamine release. Not a true allergy. Treat with Benadryl. þ TMP/SMX (Bactrim, Septra): - estimated that 1 in a million users will develop Stevens-Johnson syndrome, which may be fatal [Wolfe MS. Acute diarrhea associated with travel. AJM 1990;88(suppl 6A):34S-37S.] þ Enterovioform