Beta lactam allergy

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ß-Lactam Allergy

ß-Lactams are highly-effective, bactericidal agents often employed in 1st line empirical antibiotic regimens. The group includes:

Penicillins: e.g.

Amoxicillin, Benzylpenicillin, Co-amoxiclav (Augmentin^®), Flucloxacillin, Penicillin V (Phenoxymethylpenicillin), Piperacillin/tazobactam (Tazocin^®)

Cephalosporins: e.g.

Cefotaxime, Cefradine, Ceftazidime, Ceftriaxone, Cefuroxime.

Carbapenems:

Imipenem, Meropenem

Monobactams - not used at QMC.

Patients reporting an adverse reaction to penicillin are relatively common.

Therefore, it is important to clarify what reaction the patient actually has experienced (endorse reaction in drug card allergy box).

In some cases it is simply a common adverse drug reaction (e.g. diarrhoea or vomiting) rather than allergic in nature (e.g. rash, angiodema, anaphylaxis). In these cases the benefits of using a penicillin based regimen probably out-weigh the risks.

Crossover allergy

Patients with true allergy to penicillins should be thought to be allergic to all penicillins. They may also have a crossover-allergy to other ß-Lactams. The risk of crossover is quoted as between 2 and 16.5% for cephalosporins and 8.9% for imipenem (a carbapenem).

Recommendations for treatment and prophylaxis regimens.

If the patient has a non-serious allergy to penicillins (e.g. rash alone, with no anaphylactic symptoms or angiodema) cephalosporins/ carbapenems should still be used, when 1st line and the patient closely monitored.

Patients with serious allergic symptoms to penicillins (including previous anaphylaxis/angiodema) should avoid cephalosporins and carbapenems, where possible, and alternatives agents be administered.

For further advice on antibiotic choice please contact a medical microbiologist.

Page last edited: 16/01/2009

Caution; the antibiotic doses recommended on this website are intended for adult patients with normal renal and liver function unless otherwise stated. Dosing advice for patients with renal impairment is available here.