Bacterial Pathogens in Canine and Feline Skin Infections

Facultative pathogenic bacteria presumably seed the skin from environment or mucous membranes (2). Species involved in skin infections include coagulase-negative and -positive Staphylococci, E. coli, Proteus, and Pseudomonas(3). In cat, infected biting wounds and abscesses are much more frequent than pyoderma. Here pathogens from the oral cavity, such as Pasteurella multocida, represent the majority of clinical isolates.

dog cat skin infections begining
skin-infections-selection-dermal-pathogens

(4) Aucoin DP: Target, the antimicrobial reference guide to effective treatment. North American Compendiums Inc., 1993.

Staphylococcus pseudintermedius

Staphylococcus pseudintermedius (formerly called Staphylococcus intermedius) has been identified as a major pathogen in canine pyoderma. Spread over the skin surface by grooming, it takes advantage of changes in the local microenvironment and can become pathogenic (2).

Bacterial invasion strategies

Production of specific proteins, toxins, and enzymes enable Staphylococcus pseudintermedius to damage and infiltrate the epidermis, creating a tissue milieu conducive to invasion of secondary pathogens. Staphylococci in general are facultative intracellular bacteria, which are able to escape the host's defense mechanisms and survive phagocytosis (2).

Main Pathogens of Skin Infections in Dogs and Cats

 

Skin Infections – Baytril® Activity

(1) Blondeau JM. Steps To Antimicrobial Therapy. 2nd edition. North American Compendiums Inc. 2014, page 135

* C = bactericidal, S = bacteriostatic

0 = not likely effective due to intrinsic or acquired resistance
1+= <50% probability of in vitro susceptibility
2+= 50–74% probability of in vitro susceptibility
3+= 75–89% probability of in vitro susceptibility
4+= >90% probability of in vitro susceptibility

Ec = Escherichia coli
Pm = Proteus mirabilis
Pmult = Pasteurella multocida
Si = Staphylococcus pseudintermedius
St.sp = Streptococcus species
Pa = Pseudomonas aeuriginosa
Sasp = Staphylococcus species
Sa = Staphylococcus aureus

References
(1) Blondeau JM. Steps To Antimicrobial Therapy. 2nd edition. North American Compendiums Inc. 2014, page 135
(2) Ihrke PJ: Bacterial skin disease in the dog: a guide to canine pyoderma. Veterinary Learning Systems Kansas USA, 1996.
(3) Muller GH, Kirk RW, Scott DW: Bacterial Skin Diseases, in Muller GH, Kirk RW, Scott DW: Small Animal Dermatology, ed 4, W.B. Saunders Company Philadelphia: 211–246, 1989.
(4) Aucoin DP: Target, the antimicrobial reference guide to effective treatment. North American Compendiums Inc., 1993.