Staphylococcus pseudintermedius is the most frequent staphylococcal species isolated from canine
pyoderma. The control of S. pseudintermedius
infection is often difficult due to the expanded antimicrobial resistance phenotypes. Antibiotic resistance in staphylococcal pathogens is often associated to mobile genetic elements such as the insertion sequence IS256 that was first described as a part of the transposon Tn4001, which confers
aminoglycoside resistance in Staphylococcus aureus and in Staphylococcus epidermidis. In this study a collection of 70 S. pseudintermedius isolates from canine
pyoderma was used to investigate antimicrobial susceptibility to 15
antibiotics and the presence of IS256, not revealed in S. pseudintermedius yet. Antibiotic resistance profiling demonstrated that all S. pseudintermedius isolates had a multi-drug resistance phenotype, exhibiting simultaneous resistance to at least five
antibiotics; indeed methicillin resistant S. pseudintermedius isolates were simultaneously resistant to at least nine
antibiotics and all were also
gentamicin resistant. PCR analyses revealed the presence of IS256 in 43/70 S. pseudintemedius isolates. The association between the presence of IS256 and the resistance was particularly significant for certain
antibiotics:
cefovecin,
amikacin,
gentamicin and
oxacillin (χ(2)p-value<0.05). However, there was a striking result in frequency of strains resistant to
gentamicin and
oxacillin, suggesting a specific association between the presence of the IS256
element and the determinants for the resistance to these
antibiotics. To the best of our knowledge, this is the first report showing the detection of IS256 in S. pseudintermedius isolates and its association with antibiotic resistance. Our findings suggest that S. pseudintermedius may acquire antibiotic resistance genes through mobile genetic elements which may play a predominant role in the dissemination of multi-drug resistance.