While the One Health issues of intensive animal farming are commonly discussed, keeping
companion animals is less associated with the interspecies headway of antimicrobial
resistance. With the constant advance in veterinary standards, antibiotics are regularly
applied in companion animal medicine. Due to the close coexistence of dogs and humans,
dog bites and other casual encounters with dog saliva (e.g., licking the owner) are
common. According to our metagenome study, based on 26 new generation sequencing canine
saliva datasets from 2020 and 2021 reposited in NCBI SRA by The 10,000 Dog Genome
Consortium and the Broad Institute within Darwin's Ark project, canine saliva is rich
in bacteria with predictably transferable antimicrobial resistance genes (ARGs). In
the genome of potentially pathogenic Bacteroides, Capnocytophaga, Corynebacterium,
Fusobacterium, Pasteurella, Porphyromonas, Staphylococcus and Streptococcus species,
which are some of the most relevant bacteria in dog bite infections, ARGs against
aminoglycosides, carbapenems, cephalosporins, glycylcyclines, lincosamides, macrolides,
oxazolidinone, penams, phenicols, pleuromutilins, streptogramins, sulfonamides and
tetracyclines could be identified. Several ARGs, including ones against amoxicillin-clavulanate,
the most commonly applied antimicrobial agent for dog bites, were predicted to be
potentially transferable based on their association with mobile genetic elements (e.g.,
plasmids, prophages and integrated mobile genetic elements). According to our findings,
canine saliva may be a source of transfer for ARG-rich bacteria that can either colonize
the human body or transport ARGs to the host bacteriota, and thus can be considered
as a risk in the spread of antimicrobial resistance.
