How Should Practitioners Change Their View of Cross-Reactivity Among Beta-Lactams?
JUN 02, 2017 | CONTAGION® EDITORIAL STAFF
Meghan Jeffres, PharmD, assistant professor in the Department of Clinical Pharmacy, University of Colorado Skaggs School of Pharmacy, explains why practitioners need to think about the rate of cross-reactivity between antibiotic penicillin and specific cephalosporins.
Interview Transcript (slightly modified for readability)
“The risk of cross-reactivity between beta-lactams should be [realigned] as the cross-reactivity between specific beta-lactams. Instead of assuming a rate of cross-reactivity between penicillins and cephalosporins, [something] which is classically taught in school, we need to think about the rate of cross-reactivity between the antibiotic penicillin and specific cephalosporins.
One of the more commonly used cephalosporins is cephalexin. This is one of the oral cephalosporins that we use quite a bit in the outpatient setting. It has a similar side chain with amoxycillin and ampicillin, which is also cross-reactive with penicillin. Cefazolin, [however], does not have a similar side chain, and it does not have any cross-reactivity between those two. And so, even though, they are both first generation cephalosporins that are commonly used, they have very different rates of cross-reactivity.
Antibiotics that share a side chain have a cross-reactivity rate of approximately 20%; whereas, dissimilar antibiotics, or ones that do not have any side chain similarities, have a cross-reactivity rate of 0.
[Therefore], we really need to think about this as specific drug-to-drug cross-reactivity versus class cross-reactivity.”
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