Carriage and spread of methicillin-resistant S. pseudintermedius (MRSP) in bitches and puppies in two kennels

Staphylococcus pseudintermedius belongs to the normal canine bacterial flora and it also represents the most common opportunistic pathogen of dogs, frequently associated with skin, ear and wound infections. It is also one of the most common genital bacteria in healthy dogs as well as in dogs with reproductive problems and is frequently isolated from the bitch's vagina both in the pre- and post- partum period.S. pseudintermedius can be associated with neonatal mortality, causing necrotising dermatitis and pododermatitis, acute suppurative interstitial pneumonia toxemia and septicaemia.Excessive use of antimicrobials in breeding kennels leads to the selection of resistant bacteria strains and methicillin-resistant S. pseudintermedius (MRSP) has been isolated from colostrum and milk of breeding bitches and from puppies.MRSP strains are resistant to all beta-lactam antimicrobials and often show resistance to three or more antimicrobial classes. The same multiresistant clonal lineage ST71-J-t02-II–III has been shown to dominate among European isolates. Genetic typing identified other emerging clones in some European countries, such as ST258. A recent study showed that MRSP has an epidemic population structure, in which particularly successful lineages emerged and diversified rapidly within a weakly clonal background, through acquisition of the Staphylococcal Chromosomal Cassette (SCCmec) and other mobile genetic elements.Whole-genome sequencing (WGS) is a method that allows an extensive characterization of isolates and has been recently used to characterize MRSP strains to detect genome relatedness.There are currently few data available concerning genetic relatedness and polymorphism of MRSP strains isolated from bitches and their puppies, also in successive whelping, and in different breeding kennels.The objectives of this study were (1) to genetically characterize MRSP strains isolated from breeding bitches and their healthy puppies, and (2) to assess whether the same MRSP lineage is present in different breeding kennels and is maintained over time. In the two kennels looked at, one clone in each was dominating and found across several dogs and also over time.This study show that MRSP-clones found on the bitches were isolates from puppies from different parturitions that strongly suggest that the puppies are colonized by spread from their mothers.