Authors: Narváez Sonsiray Álvarez, Fernández Ingrid, Patel Nikita V, Sánchez Susan
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Rapid Detection of *Rhodococcus equi* and Antimicrobial Resistance in Foals *Rhodococcus equi* remains a significant cause of mortality in foal populations worldwide, and the emergence of multidrug-resistant (MDR) strains is complicating therapeutic decisions when time-critical treatment is essential. Álvarez and colleagues developed and validated a multiplex quantitative PCR assay capable of simultaneously identifying *R. equi* and detecting two key macrolide resistance genes (erm(46) and erm(51)) from equine respiratory samples. The assay demonstrated excellent analytical performance, with limits of detection below 12 genome copies per reaction for all three genetic targets individually and in combination, coupled with amplification efficiencies between 90–147%; critically, the method showed no cross-reactivity with normal equine respiratory flora or common respiratory pathogens, ensuring high specificity in clinical samples. For practitioners, this multiplex qPCR represents a significant advance in rapid diagnosis and resistance profiling, potentially enabling faster, more targeted antimicrobial selection during the critical early stages of *R. equi* pneumonia when empirical treatment decisions are most consequential. The tool addresses a genuine gap in equine diagnostics by collapsing diagnosis and resistance determination into a single, rapid molecular assay rather than waiting for traditional culture-based susceptibility results.
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Practical Takeaways
- •This qPCR test enables faster diagnosis of R. equi in foals compared to traditional culture methods, allowing earlier treatment decisions
- •The test simultaneously identifies macrolide resistance genes, helping practitioners select appropriate antibiotics and avoid ineffective treatments in MDR cases
- •Practitioners can obtain resistance profile results during the same diagnostic window as infection confirmation, improving treatment efficiency and potentially reducing foal mortality
Key Findings
- •Multiplex qPCR successfully detects R. equi housekeeping gene choE with limit of detection below 12 genome copies per reaction
- •Macrolide resistance genes erm(46) and erm(51) detected with high sensitivity and amplification efficiency between 90-147%
- •No cross-reactivity observed with equine respiratory tract normal flora or common equine respiratory pathogens
- •Diagnostic tool provides rapid detection of R. equi infection and antimicrobial resistance profile to guide treatment selection