Claritin combats bacterial resistance

Abstract

The common antihistamine loratadine—the active ingredient in some over-the-counter allergy medicines, including Claritin—makes some species of antibiotic-resistant bacteria susceptible to antibiotics in lab experiments (ACS Infect. Dis. 2019, DOI: 10.1021/acsinfecdis.9b00096). Loratadine also breaks up bacterial biofilms, which can form on implants and catheters. The results offer a new route to developing drugs for these hard-to-treat infections, the researchers say. Study authors Meghan S. Blackledge and Heather B. Miller of High Point University treated cultures of Staphylococcus aureus and S. epidermis, including strains isolated from hospital-acquired or community-acquired infections, with a common antibiotic, oxacillin. S. epidermis strains’ responses to the antibiotic were unaffected by the loratadine. But the antihistamine was surprisingly effective against S. aureus. Strains that were treated with oxacillin and loratadine were 8 to 500 times as sensitive to the antibiotic. Furthermore, loratadine blocked biofilm formation and broke up preformed biofilms of all S. aureus strains tested. A knockout