Magnetic Nanoparticles Detect Amoxicillin Allergy With 98% Sensitivity in Early Tests

A multidisciplinary team at the University of Malaga in Spain has developed a new diagnostic technology, based on magnetic nanoparticles, that can detect allergy to beta-lactam antibiotics such as amoxicillin and other penicillins more precisely and rapidly than existing tests. The findings are published in the journal Materials Today Bio.

The platform uses nanoparticles about 30 nanometers across, with an iron oxide core and a silica shell, that act like a tiny magnet covered with molecular "hooks." If a patient's blood contains the IgE antibodies responsible for the allergy, the nanoparticles capture them more readily than conventional methods, said Ezequiel Pérez-Inestrosa, a professor of organic chemistry at the University of Malaga and one of the study's authors.

Penicillin allergy is widely overdiagnosed: while between 8% and 25% of the population reports being allergic to these antibiotics, only 1% to 10% actually are, said María José Torres, a professor of medicine who also led the study. Incorrect diagnoses lead doctors to prescribe alternative drugs that are generally less effective, more toxic, and contribute to the emergence of bacterial resistance.

For the study, researchers analyzed blood samples from nearly 100 people — 50 patients with confirmed amoxicillin allergy and 44 who tolerated the antibiotics — comparing the new platform with two existing techniques, ImmunoCAP and conventional RAST. For amoxicillin specifically, the new platform achieved 98% sensitivity, compared with around 17% for ImmunoCAP, the most widely used commercial test.

The method also avoids drug provocation tests, in which patients are given the medication itself to see if they react, a procedure that carries risks. The authors say further, larger multicenter studies and clinical validation are needed before the technology can be introduced into hospitals and used routinely.