Exploiting the healthy microflora to develop new treatments for Staphylococcus pseudintermedius infection in canine atopic dermatitis

Abstract

Staphylococcus pseudintermedius is a commensal microorganism and opportunistic pathogen, most frequently responsible for causing pyoderma and secondary skin infections in dogs with atopic dermatitis, one of the most common causes for antimicrobial prescriptions in small animal practice. The emergence of methicillin- and multidrug-resistant S. pseudintermedius strains has resulted in some infections being deemed untreatable by many veterinarians. The potential for zoonotic transmission also makes S. pseudintermedius a public health concern; thus, identifying novel antimicrobial treatments for S. pseudintermedius is a priority in human and animal health.

Bacteriocins, ribosomally-synthesised peptides, provide an alternative to antibiotics, displaying potent, specific, antimicrobial activity against strains closely related to or sharing the same niche as the producing bacteria.

This study explored the skin microbiota of healthy dogs, investigating the prevalence of commensal staphylococci, and bacteriocin production by the species isolated.

Staphylococci were isolated from skin swabs of 121 healthy dogs; 166 isolates, belonging to 20 species, including two proposed novel species, were identified.

Twelve methicillin-resistant isolates were identified, seven of which were multidrug-resistant, all belonging to coagulase-negative staphylococci species.

Thirteen isolates belonging to eight species displayed inhibitory activity against S. pseudintermedius via deferred-antagonism assay. One Staphylococcus devriesei isolate, H14, inhibited ten clinically relevant S. pseudintermedius and two Staphylococcus aureus strains in cell- free supernatant assays, reducing growth by over 70%, including methicillin-resistant strains. Genome-mining identified two novel bacteriocin gene clusters from S. devriesei H14. Nine further novel bacteriocin gene clusters were identified, from S. pseudintermedius, Staphylococcus warneri, Staphylococcus simulans, and Staphylococcus xylosus. These bacteriocins show promise as novel therapies for S. pseudintermedius infections in canine atopic dermatitis.