Research article - Peer-reviewed, 2020
Potential for residual contamination by Streptococcus equi subspp equi of endoscopes and twitches used in diagnosis of carriers of strangles
Svonni, Elin; Andreasson, Mikaela; Fernstrom, Lise-Lotte; Ryden, Anneli; Pringle, John; Riihimaki, MiiaAbstract
Background Endoscopic examinations are essential for diagnosis and treatment of strangles (S equi infection) in horses. However, even after disinfection, endoscopes may retain viable bacteria or bacterial DNA. Twitches are commonly used during endoscopic examinations and can thus also potentially transmit the organism to other horses.Objectives To evaluate the efficacy of different disinfectant methods to eliminate S equi from experimentally contaminated endoscopes and twitches and the effectiveness of field disinfection of endoscopes used in sampling carriers of S equi.Study design Experimental contamination and observational field study.Methods One endoscope and 30 twitches were contaminated with standardised S equi broth solutions. The endoscope was disinfected following three protocols using various disinfectants for manual disinfection. A fourth protocol used an automated endoscope reprocessor (AER). The twitches (n = 30) were disinfected following eight different disinfecting protocols. Three endoscopes used in sampling for silent carriers were disinfected following a field-based protocol. After each protocol the endoscopes and twitches were sampled for S equi by culture and qPCR.Results Following experimental contamination all endoscope disinfection protocols, apart from 1/6 of the ethanol protocol were S equi culture negative. However, no endoscope disinfection protocol completely eliminated retention of S equi DNA. Field disinfection of endoscopes after sampling carriers yielded no culture positives and all but one (13/14) were qPCR negative. All twitches disinfected following experimental contamination were culture negative but sodium hypochlorite was the only disinfectant that completely eliminated detection of S equi DNA.Main limitations Experimental contamination may not reflect the numbers of S equi transferred to endoscopes or twitches during use on silent carriers and purulent secretions from infected horses may influence survival of S equi.Conclusions While most disinfection methods appear to ensure removal of cultivable S equi, residual DNA can remain on both endoscopes and twitches.Keywords
horse; cleaning; disinfection; equipmentPublished in
Equine Veterinary Journal2020, volume: 52, number: 6, pages: 884-890
Publisher: WILEY
Authors' information
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Andreasson, Mikaela
Swedish Board Agr
Swedish University of Agricultural Sciences, Department of Biomedical Science and Veterinary Public Health
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Swedish University of Agricultural Sciences, Department of Clinical Sciences
UKÄ Subject classification
Clinical Science
Publication Identifiers
DOI: https://doi.org/10.1111/evj.13248
URI (permanent link to this page)
https://res.slu.se/id/publ/104989