Rhodococcus Equi: Challenges to Treat Infections and to Mitigate Antimicrobial Resistance

Rhodococcus equi, a gram-positive facultative intracellular pathogen and a soil saprophyte, is one of the most common causes of pneumonia in young foals. It poses a threat to the economy in endemic horse -breeding farms and to animal welfare annually. Many farms use thoracic ultrasonographic screening and antimicrobial treatment of subclinically affected foals as a preventive measure against severe R. equi infec-tions. The wide use antimicrobials to treat subclinically affected foals has contributed to the emergence of multidrug resistant (MDR) -R. equi in both clinical isolates from sick foals and in the environment of horse-breeding farms. Alternatives to treat foals infected with MDR -R. equi are scarce and the impact of the emergence of MDR -R. equi in the environment of farms is still unknown. The aim of this review is to discuss the emergence of MDR -R. equi in the United States and the challenges faced to guide antimicro-bial use practices. Reduction of antimicrobial use at horse-breeding farms is essential for the preservation of antimicrobial efficacy and, ultimately, human, animal, and environmental health. & COPY; 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )