Streptococcus equi subspecies equi from strangles suspected equines: molecular detection, antibiogram profiles and risk factors.
Authors: Bekele Demsew, Dessalegn Bereket, Tadesse Belege, Abey Solomon Lulie
Journal: BMC veterinary research
Summary
# Editorial Summary: *Streptococcus equi* Detection and Antimicrobial Resistance in Strangles Cases Strangles remains a costly infectious disease in equine populations, yet the prevalence of virulent strains carrying the SeM gene—which encodes a key immune-evasion protein—and their antimicrobial resistance profiles are poorly documented in many regions. Between July and December 2022, researchers in Ethiopia collected 160 nasopharyngeal swabs from clinically suspected cases across five districts, isolating *Streptococcus equi subspecies equi* from just under one-third of samples; molecular analysis revealed that approximately 31% of these isolates harboured the SeM gene. Resistance to tetracycline, erythromycin and vancomycin exceeded 75% across the 16 SeM-positive isolates, a concerning finding given these drugs' historical use in strangles management. Management practices emerged as critical risk factors, with animals sharing feed containers, water troughs or sleeping quarters showing 5.97–7.74 times greater odds of harbouring the infection compared to those in separated housing. For practitioners, these findings reinforce the necessity of rigorous biosecurity protocols—particularly regular disinfection of communal feeding and watering equipment—whilst prompting reconsideration of empirical antibiotic selection in endemic areas where resistance prevalence is high.
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Practical Takeaways
- •Regular cleaning and disinfection of shared feed containers and water troughs is critical to reduce strangles transmission in group settings
- •Isolate affected animals and segregate housing (including separate night turnout areas) to interrupt disease spread, particularly when SeM-positive strains are circulating
- •Be aware that common antibiotics (tetracycline, erythromycin) show high resistance rates—work with your veterinarian to guide treatment decisions based on local resistance patterns
Key Findings
- •Streptococcus equi was isolated from 31.87% (51/160) of suspected strangles cases, with 31.37% (16/51) carrying the virulent SeM gene
- •High antimicrobial resistance observed: tetracycline 81.5%, erythromycin 81.5%, and vancomycin 75.5% resistance among SeM-positive isolates
- •Sharing feed containers increased strangles risk 7.59-fold (AOR=7.59, 95% CI=1.44-39.93) and shared water troughs increased risk 7.74-fold (AOR=7.74, 95% CI=1.44-41.01)
- •Spending the night together increased strangles transmission risk 5.97-fold (AOR=5.97, 95% CI=1.41-25.37)