Streptococcus equi Subspecies equi From Strangles Suspected Equines: Molecular Detection, Antibiogram Profiles and Risk Factors
Authors: Bekele Demsew, Desalegn Bereket, Tadesse Belege, Abey Solomon Lulie
Summary
# Editorial Summary: S. equi Detection and Antimicrobial Resistance in Ethiopian Equine Populations Strangles remains a costly and highly contagious bacterial disease affecting equine operations worldwide, yet epidemiological data and resistance profiles remain limited in many regions. Researchers in central Ethiopia conducted a cross-sectional study across five districts, collecting 160 nasal and pharyngeal swabs from clinically suspected cases and analysing isolates for the virulence-associated SeM gene using PCR, whilst simultaneously performing antimicrobial susceptibility testing via Kirby-Bauer disc diffusion. S. equi subspecies equi was isolated from nearly one-third of samples (31.87%), with 31.37% of positive isolates carrying the SeM gene—a marker of enhanced pathogenicity—and alarmingly high resistance rates to tetracycline, erythromycin and vancomycin (75.5–81.5%), limiting conventional therapeutic options. Shared management practices emerged as significant epidemiological risk factors: animals using communal feed containers and water troughs were 7.6 and 7.7 times more likely to test positive respectively, whilst co-housing overnight increased risk 6-fold, emphasising transmission via contaminated fomites rather than direct contact alone. These findings underscore the critical importance of biosecurity protocols in endemic areas, particularly rigorous cleaning and disinfection of shared equipment, alongside the urgent need for judicious antimicrobial stewardship and consideration of alternative treatments such as penicillin-based therapy where susceptibility permits.
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Practical Takeaways
- •Implement strict biosecurity: clean and disinfect shared feed containers and water troughs regularly to reduce transmission in multi-animal facilities
- •Consider isolating affected animals from group housing, as shared overnight accommodation significantly increases strangles spread
- •Be aware that common antibiotics (tetracycline, erythromycin, vancomycin) show high resistance rates in local strains; coordinate with veterinarian on appropriate antimicrobial therapy
Key Findings
- •Streptococcus equi was isolated from 31.87% (51/160) of clinically suspected samples, with 31.37% (16/51) carrying the SeM gene
- •High antimicrobial resistance observed: tetracycline 81.5%, erythromycin 81.5%, and vancomycin 75.5% resistance among isolates
- •Sharing feed containers increased strangles likelihood 7.59-fold (AOR = 7.59; 95% CI = 1.44–39.93)
- •Shared water troughs and overnight housing were significant risk factors with 7.74-fold and 5.97-fold increased odds respectively