Frane Banovic1,2,3, Keith Linder4, Thierry Olivry2,3. 1. Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, 2200 College Station Road, Georgia, GA, 30605, USA. 2. Comparative Medicine Institute, NC State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA. 3. Department of Clinical Sciences, College of Veterinary Medicine, NC State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA. 4. Department of Population Health and Pathobiology, College of Veterinary Medicine, NC State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA.
Abstract
BACKGROUND: The microscopic and microbial features of the spreading epidermal collarettes of canine exfoliative superficial pyodermas are poorly characterized. OBJECTIVES: To characterize the clinical, cytological, microbial and histopathological features of epidermal collarettes in five dogs. RESULTS: Cytology from the margins of collarettes identified neutrophils, extracellular and intracellular cocci within neutrophils but no acantholytic keratinocytes. Phenotypic and genotypic analyses identified all bacterial isolates from the centre and margin of five epidermal collarettes as Staphylococcus pseudintermedius. PCRs of collarette-associated Staphylococcus strains did not amplify genes encoding for the known exfoliative toxins expA and expB, whereas the predicted siet and speta amplification products were detected in all isolates. Microscopically, epidermal collarettes consisted of interfollicular, epidermal spongiotic pustules. Advancing edges of lesions consisted of peripheral intracorneal clefts in the deep stratum disjunctum above an intact stratum compactum; they contained lytic neutrophil debris, bacterial cocci and fluid, but no acantholytic keratinocytes. This intracorneal location of bacteria was confirmed using Gram stains and fluorescent in situ hybridization with eubacterial- and Staphylococcus-specific probes. The indirect immunofluorescence staining patterns of desmoglein-1, desmocollin-1, claudin-1, E-cadherin and corneodesmosin were discontinuous and patchy in areas of spongiotic pustules, whereas only that of corneodesmosin was weaker and patchy in advancing collarette edges. CONCLUSION: Epidermal collarettes represent unique clinical and histological lesions of exfoliative superficial pyodermas that are distinct from those of impetigo and superficial bacterial folliculitis. The characterization of possible causative staphylococcal exfoliatin proteases and the role of corneodesmosin in collarette pathogenesis deserve further investigation.
BACKGROUND: The microscopic and microbial features of the spreading epidermal collarettes of canine exfoliative superficial pyodermas are poorly characterized. OBJECTIVES: To characterize the clinical, cytological, microbial and histopathological features of epidermal collarettes in five dogs. RESULTS: Cytology from the margins of collarettes identified neutrophils, extracellular and intracellular cocci within neutrophils but no acantholytic keratinocytes. Phenotypic and genotypic analyses identified all bacterial isolates from the centre and margin of five epidermal collarettes as Staphylococcus pseudintermedius. PCRs of collarette-associated Staphylococcus strains did not amplify genes encoding for the known exfoliative toxins expA and expB, whereas the predicted siet and speta amplification products were detected in all isolates. Microscopically, epidermal collarettes consisted of interfollicular, epidermal spongiotic pustules. Advancing edges of lesions consisted of peripheral intracorneal clefts in the deep stratum disjunctum above an intact stratum compactum; they contained lytic neutrophil debris, bacterial cocci and fluid, but no acantholytic keratinocytes. This intracorneal location of bacteria was confirmed using Gram stains and fluorescent in situ hybridization with eubacterial- and Staphylococcus-specific probes. The indirect immunofluorescence staining patterns of desmoglein-1, desmocollin-1, claudin-1, E-cadherin and corneodesmosin were discontinuous and patchy in areas of spongiotic pustules, whereas only that of corneodesmosin was weaker and patchy in advancing collarette edges. CONCLUSION: Epidermal collarettes represent unique clinical and histological lesions of exfoliative superficial pyodermas that are distinct from those of impetigo and superficial bacterial folliculitis. The characterization of possible causative staphylococcal exfoliatin proteases and the role of corneodesmosin in collarette pathogenesis deserve further investigation.
Authors: Hester Rynhoud; Brian M Forde; Scott A Beatson; Sam Abraham; Erika Meler; Ricardo J Soares Magalhães; Justine S Gibson Journal: Front Vet Sci Date: 2021-04-23