Bacteria, scratching, contamination due to poor grooming, seborrhea, parasitic infestation, hormonal factors, local irritants, or allergies may cause bacterial infection called pyoderma. In dogs, superficial bacterial folliculitis is the most common form of pyoderma. The predominant pathogen that causes superficial pyoderma is Staphylococcus pseudintermedius, a generally non-pathogenic bacterium that resides on the skin surfaces of dogs. Genetic, environmental, and immunological factors may cause the bacterium to switch from commensal to pathogenic.
Follicular inflammation also occurs with other conditions, including demodicosis, dermatophytosis and a variety of immune-mediated skin disorders. Superficial bacterial folliculitis can often become a chronic and/or recurrent condition if the primary underlying cause is not identified and adequately resolved or controlled. Causes for the persistence or recurrence of pyoderma include inappropriate therapy (drugs used, duration of treatment), lack of diagnostics, and methicillin resistance. Methicillin resistance denotes that the organisms are resistant to most beta lactam antibiotics. Many methicillin-resistant staphylococci are also multi-drug resistant (that is, resistant to at least 3 families of antibiotics).1,2
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Methicillin-resistant Staphylococcus pseudintermedius (MRSP) was significantly associated with pyoderma and, to a lesser extent, with wound infections and otitis externa, but also with pneumonia and urinary tract infections. MRSP is a threat to canine health worldwide. In Germany, 7.4% of dogs were found to be MRSP positive at admission to veterinary clinics.3 Several studies have found that from 69% to 87.4% of healthy dogs carry Staphylococcus pseudintermedius as part of their normal skin flora. The zoonotic potential is not as striking as that of Staphylococcus aureus but the organism has been isolated both from healthy owners with infected pets and from veterinarians working at small animal clinics.4
- Bajwa J. Canine superficial pyoderma and therapeutic considerations. The Canadian Veterinary Journal. 2016;57(2):204-206.
- Joffe D, Goulding F, Langelier K, et al. Prevalence of methicillin-resistant staphylococci in canine pyoderma cases in primary care veterinary practices in Canada: A preliminary study. The Canadian Veterinary Journal. 2015;56(10):1084-1086.
- Duim B, Verstappen KM, Broens EM, et al. Changes in the Population of Methicillin-Resistant Staphylococcus pseudintermedius and Dissemination of Antimicrobial-Resistant Phenotypes in the Netherlands. Fenwick BW, ed. Journal of Clinical Microbiology. 2016;54(2):283-288. doi:10.1128/JCM.01288-15.
- Kjellman EE, Slettemeås JS, Small H, Sunde M. Methicillin‐resistant Staphylococcus pseudintermedius (MRSP) from healthy dogs in Norway – occurrence, genotypes and comparison to clinical MRSP . MicrobiologyOpen. 2015;4(6):857-866. doi:10.1002/mbo3.258.