TDK conference 2025

Antimicrobial resistance (AMR) is one of the most serious global public health problems today. Bacterial skin infections are the most common reason for antibiotic use in dogs. Our goal was to determine the phenotypic susceptibility of Staphylococcus pseudintermedius strains isolated from the skin of dogs to the most commonly used antibiotics.

During our research, we performed phenotypic susceptibility testing on 131 S. pseudintermedius isolates, of which 10 strains were methicillin-resistant Staphylococcus pseudintermedius (MRSP). We determined the minimum inhibitory concentration (MIC) values of a total of 12 active substances against the isolates.

In the case of methicillin-sensitive (MSSP) strains, we detected the following sensitivity: for the AMEG-D category trimethoprim-sulfamethoxazole, 79.3% of strains were sensitive, while for doxycycline, only 44.6% were sensitive. For the AMEG-C category amoxicillin-clavulanic acid, 79.3% of isolates were sensitive, 82.6% of the isolates were sensitive to cefalexin, 73.6% to gentamicin, 92.6% to amikacin, only 56.2% to clindamycin, and 68.6% to florfenicol. For AMEG-B category cefovecin, 86.7% of strains were sensitive, while for enrofloxacin and marbofloxacin, only 44.6% and 28.1% were sensitive, respectively. It is important to note that in the case of the latter two active substances, a further significant proportion of the strains (33.9%) were moderately sensitive. For the AMEG-A category rifampicin, 94.2% of the strains were sensitive.

Amikacin and rifampicin proved to be the most effective against MRSP isolates. The proportion of sensitive strains was 60.0% in the case of the former and 90.0% in the case of the latter. In addition, it is worth highlighting florfenicol, which, although only 40.0% of strains were sensitive to this active substance, a further 50.0% of strains were moderately sensitive. In the case of the other active substances, more than half of the strains proved to be resistant.

In summary, most of the active substances tested remain effective in treating MSSP-induced skin infections. Among the orally administered active substances, amoxicillin-clavulanic acid and cephalexin proved to be the most effective. Against MRSP isolates, amikacin and rifampicin proved to be the most effective, with florfenicol emerging as a potential alternative. A worrying trend is that a significant proportion of strains showed only moderate sensitivity to AMEG-B category fluoroquinolones.