Potential for residual contamination by Streptococcus equi subspp equi of endoscopes and twitches used in diagnosis of carriers of strangles.

Summary

# Editorial Summary Strangles diagnosis relies heavily on endoscopic examination and nasopharyngeal sampling, yet the potential for cross-contamination between horses through inadequately disinfected equipment has received limited scrutiny. This Swedish research team investigated whether *Streptococcus equi* subsp. *equi* could survive on endoscopes and twitches despite standard disinfection protocols, using both bacterial culture and PCR analysis to detect viable organisms and residual DNA. The findings revealed that viable bacteria persisted on both endoscopes and twitches following routine disinfection procedures, with bacterial DNA detected even after cleaning—a concerning result given the highly contagious nature of strangles and the established role of carrier horses in disease transmission. These results underscore the critical importance of rigorous disinfection protocols between examinations, particularly when handling multiple horses during outbreak investigations or in high-risk settings, and suggest that current cleaning standards may require reassessment to eliminate the risk of iatrogenic transmission. Practitioners should review their equipment sterilisation procedures and consider implementing enhanced disinfection measures or single-use sampling equipment where feasible to prevent inadvertent spread of this economically significant disease.

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Key Findings

• •Endoscopes retain viable Streptococcus equi bacteria and/or bacterial DNA even after standard disinfection procedures
• •Twitches used during endoscopic examinations can potentially harbor and transmit the causative organism between horses
• •Equipment contamination represents a risk factor for iatrogenic transmission of strangles in carrier diagnosis protocols

Conditions Studied

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