EQUINE | Abstracts
A study of the Environmental Survival
of Streptococcus equi subspecies equi
A. E. Durham
Y. S. Hall L. Kulp
C. Underwood
Background
Streptococcus equi represents a common hazard to
equids worldwide. Environmental contamination with
bacteria shed from an infected horse may represent a
significant source of contagion and further knowledge
of ex vivo bacterial survival under different conditions
is important for disinfection and isolation protocols.
Objectives
To determine the potential duration of survival and
vigour of growth of S. equi inoculated onto surfaces
relevant to equine veterinary practice and stabling in
summer and winter.
Study design
Repeat sampling of environmental inocula of S. equi.
Methods
Cultures of S. equi were inoculated onto wood, a shoe
sole, cotton overalls, inside a nasogastric tube, inside
a dental rasp, in a wet plastic bucket and onto a fence
post both in the summer and winter seasons. Frequent
resampling and culture from the inoculated sites was
conducted until no viable bacteria were found. Bacterial
viability was determined by both duration (time to first
negative culture) and vigour of growth (growth score
over the first 3 days of culture) and compared between
inoculated sites and times of year.
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Results
Bacterial viability was enhanced by a wet local
environment and by the winter season. Survival tended
to be short in the summer (up to 9 days in wet sites
and up to 2 days in dry sites) but much longer in the
winter (up to 34 days in wet sites and up to 13 days in
dry sites). Vigour of bacterial growth was also greater
in the winter than in the summer as judged by 3‐day‐
growth scores.
Main limitations
Direct comparison with the variable size and nature of
naturally shed infectious material is difficult.
Conclusions
Veterinarians and personnel handling horses should
be aware that S. equi may survive in an equine
environment for longer than previously found,
especially when protected by wet and cold conditions.
https://onlinelibrary.wiley.com/doi/abs/10.1111/evj.12840
• Equine Health Update •