Spread of Multidrug-Resistant Rhodococcus equi, United States

This certainly should make horse breeders sit up and take notice. The article above offers non-macrolide alternative but none as sage and affordable as erythromycin.
DrO

Spread of Multidrug-Resistant Rhodococcus equi, United States
Emerg Infect Dis. 2021 Feb;27(2):529-537.
Authors
Sonsiray Álvarez-Narváez, Steeve Giguère, Noah Cohen, Nathan Slovis, José A Vázquez-Boland

Abstract

Multidrug resistance has been detected in the animal and zoonotic human pathogen Rhodococcus equi after mass macrolide/rifampin antibioprophylaxis in endemically affected equine farms in the United States. Multidrug-resistant (MDR) R. equi emerged upon acquisition of pRERm46, a conjugative plasmid conferring resistance to macrolides, lincosamides, streptogramins, and, as we describe, tetracycline. Phylogenomic analyses indicate that the increasing prevalence of MDR R. equi since it was first documented in 2002 is caused by a clone, R. equi 2287, attributable to coselection of pRErm46 with a chromosomal rpoBS531F mutation driven by macrolide/rifampin therapy. pRErm46 spillover to other R. equi genotypes has given rise to a novel MDR clone, G2016, associated with a distinct rpoBS531Y mutation. Our findings illustrate that overuse of antimicrobial prophylaxis in animals can generate MDR pathogens with zoonotic potential. MDR R. equi and pRErm46-mediated resistance are currently disseminating in the United States and are likely to spread internationally through horse movements.

Keywords: MDR R. equi; TnRErm46; United States; antimicrobial resistance; bacteria; bacterial infection; erm(46); macrolide resistance; multidrug-resistant Rhodococcus equi; pRErm46; rifampin resistance; zoonoses.