Dam-to-offspring transmission and persistence of Staphylococcus pseudintermedius clones within dog families

Staphylococcus pseudintermedius is an opportunistic pathogen that causes mainly skin infections in dogs. Although vertical transmission of S. pseudintermedius strains from dam to offspring has been reported, the persistence of the dam's strains in offspring over long periods of time is virtually unknown.

The aim of this study was to investigate to what extent S. pseudintermedius clones resident on the dam may be transmitted to and persist in offspring.

A total of 18 dogs and 50 of their offspring, which had been separated from their mother for between 1 month and 9 years, were enrolled in the study.

Mouth and perineal swabs taken from all dogs were subjected to selective enrichment and plating on blood agar. Presumptive S. pseudintermedius colonies were confirmed by a species-specific PCR and typed by pulsed-field gel electrophoresis.

Staphylococcus pseudintermedius was isolated from both the dam and at least one offspring in 12 of the 18 dog families. Pulsed-field gel electrophoresis confirmed carriage of indistinguishable or closely related strains in the dam and offspring within four families, despite the fact that they had lived separately for between 2 and 48 months before sampling.

Our results indicate that S. pseudintermedius clones that are transmitted from the dam to the puppies around birth may persist in the offspring for long periods of time. The study contributes to the current understanding of the mechanisms of spread of S. pseudintermedius in dogs and highlights the need for research to elucidate the role of bacterial and host genetic factors in colonization.