Isolation of Staphylococcus pseudintermedius in Immunocompromised Patients from a Single Center in Spain: A Zoonotic Pathogen from Companion Animals

<i>Staphylococcus pseudintermedius</i>, a commensal opportunistic bacterium predominantly residing in the skin of companion animals, particularly dogs, has the potential to induce skin and soft tissue infections in pets, and zoonotic infections, including catheter-related complications. This study documents four cases of <i>S. pseudintermedius</i> infection or colonization in patients who had close contact with dogs or cats. Identification of the bacterial species was performed using MALDI-TOF mass spectrometry, and antibiotic susceptibility was determined using microdilution assay. DNA was sequenced using Nanopore technology followed by in silico analysis. Three isolates were multidrug resistant, including resistance to methicillin, with one belonging to the prevalent European lineage ST551, and the other two were attributed to a novel multilocus sequence type, ST2672. The remaining isolate was attributed to the novel multilocus sequence type ST2673 and was methicillin susceptible. All four isolates exhibited an array of virulence factors that contributed to colonization, damage to host immune cells, and biofilm formation. All the ST551 isolates included in the comparative analysis displayed clonality within the European continent. The importance of describing zoonotic infections associated with <i>S. pseudintermedius</i> resides in the scarcity of available scientific literature, further accentuated by its heightened resistance profile and potential complications, particularly in the context of catheter-related infections.