This Is AuburnElectronic Theses and Dissertations

Navigating the Complexities of Disease Prevention, Alternative Treatments, and Multi-Drug Resistant Rhodococcus equi Mitigation Strategies




Higgins, Courtney

Type of Degree

Master's Thesis


General Veterinary Medicine

Restriction Status


Restriction Type

Auburn University Users

Date Available



The opportunistic pathogen, Rhodococcus equi, is a robust soil saprophyte present in the environment of horse-breeding farms and an important cause of pulmonary disease in foals at endemic farms. As an effort to prevent severe disease, endemic farms rely on early identification of lung lesions using thoracic ultrasonographic screening (TUS) of foals and administration of antimicrobials in foals with sonographic evidence of pulmonary abscesses or consolidations irrespective of clinical signs. This method of screening and treating has led to the overuse of antimicrobials and has been linked to the emergence of multidrug resistant (MDR)-R. equi in both clinical and environmental R. equi isolates. The implementation of judicious use of antimicrobials at endemic farms is crucial for mitigating antimicrobial resistance (AMR); however, the long-term impacts of the overuse of antimicrobials is unknown. Here, we investigate the main challenges to preventing R. equi disease, finding alternative treatments, and the potential of long-term impact of antimicrobial residue accumulation in the environment of farms on MDR-R. equi mitigation strategies.