Necrotizing fasciitis associated with Acinetobacter lactucae and Bacillus paramobilis infections in 2 dogs

Two immunocompetent dogs from separate households were presented to a tertiary referral hospital with soft tissue wounds attributable to severe bacterial infection. A 5-y-old, castrated male Golden Retriever dog (case 1) was presented with extensive hemorrhagic cellulitis of the forelimbs and neck that developed over 48-h and was attributable to Acinetobacter lactucae infection. Additionally, an 8-y-old, spayed female Labrador Retriever-mix dog (case 2) sustained a deep penetrating wound over the left hip that progressed over 24 h to necrotizing fasciitis, from which Bacillus paramobilis was isolated. Histopathologic findings in both cases included severe acute, skeletal muscle necrosis and necrosuppurative myofasciitis, dermatitis, and panniculitis with intralesional rod-shaped bacteria. Whole-genome sequencing and phylogenetic analysis of the bacterial isolates revealed numerous cytolytic toxins and other virulence genes carried by the isolates, expanding the profile of these 2 bacteria. To our knowledge, canine cases of A. lactucae and B. paramobilis associated with necrotizing fasciitis have not been reported previously. In both cases, progression from an inciting incident to septic disease was extremely rapid, occurring within 48 h in case 1 and 24 h in case 2, underscoring the fulminant nature of necrotizing fasciitis.