Abscess-Forming Inflammatory Granulation Tissue with Gram- Positive Cocci and Prominent Eosinophil Infiltration in Cats: Possible Infection of Methicillin-resistant Staphylococcus

Abstract

Abstract. We occasionally encounter feline cervical or mesenteric lesions diagnosed histopathologically as abscess or inflammatory granulation tissue with eosinophil infiltration. Gram-positive cocci accompany the lesions. In the present study, such lesions obtained from 27 cats were examined to evaluate the histopathologic features and the nature of the causative bacteria. The average age was 7.3 Ϯ 3.5 years. No sex predilection was observed. Most frequent locations of the lesions included the abdominal cavity with/without mesenteric lymph nodes (11/ 27, 41%) and subcutaneous tissue or lymph nodes of the neck (9/27, 33%). Common clinical presentation was a localized mass. Grossly, the lesions contained abscesses in the center and were surrounded by fibrous tissue. Microscopically, the necrotic zone contained bacterial colonies. Large numbers of eosinophils and macrophages infiltrated the area surrounding the necrotic tissue. The surrounding connective fiber-rich granulation tissue demarcated the eosinophilic abscess. The bacteria were Gram-positive cocci in 23 of the 27 cats and were positive for anti-staphylococcus antiserum in 19 of the 23 cats. In 15 out of 17 lesions, the colonies expressed immunoreactivity to penicillin-binding protein 2Ј, which is a drug-resistance gene product of methicillin-resistant Staphylococcus (MRS) species. These findings suggest strongly that MRS causes this type of infectious lesion.

Recurrent feline gastrointestinal eosinophilic sclerosing fibroplasia and presumptive eosinophilic cystitis in a domestic short-haired cat: a case report

“…It is presumed that eosinophils cause the specific fibrosis of FGESF and play a key role in the pathogenesis of FGESF (Craig et al 2009;Suzuki et al 2013;Weissman et al 2013). Previously, bacterial or fungal infection has been considered to be involved in the pathogenesis of FGESF (Ozaki et al 2003;Grau-Roma et al 2014), but in subsequent cases, no pathogens were detected (Craig et al 2009;Suzuki et al 2013;Weissman et al 2013). In the most recent study bacteria were found in nine of 13 FGESF cases (Linton et al 2015).…”

Methicillin-resistantStaphylococcus aureusin Cat and Owner

“…Histopathologic findings demonstrated ulcers and dermal granulation tissue with linearly arranged eosinophils, mast cells, neutrophils, and plasma cells between dense, homogeneous collagen bundles (sclerosing dermatitis). This pattern of inflammation is distinct from most staphylococcal infections of the skin, and it has been suggested that this uncommon histologic finding in cats is associated with methicillin-resistant staphylococcal infection ( 1 ). …”

Jejunal fibroplasia in a rat

“…This disease has been reported in cats and pumas ( Puma concolor ) [2,3,4, 9]. The etiology of this disease is the infection (bacteria, fungi and nematodes), foreign body or unknown [2,3,4, 7, 9]. Macroscopically, the lesion is observed as an ulcerated intramural mass at the pyloric sphincter and the ileocecocolic junction [2,3,4, 9].…”

“…Microscopically, all lesions include a very characteristic trabecular pattern of dense collagen with proliferation of the reactive large myofibroblasts. Many lesions also have numerous eosinophils and mast cells [2, 3, 7, 9]. In cats, the term ‘FGESF’ is considered appropriate based on these microscopic characteristics [2].…”

“…It is considered that fibrogenic factors, such as major basic protein, transforming growth factor (TGF)-β, interleukin (IL)-1β and IL-13 secreted by infiltrated eosinophils and mast cells into the lesion, are related to the proliferation of the fibroblasts and the formation of the screlosing fibers as the pathogenesis of the FGESF [1,2,3,4, 7, 9]. In present case, many macrophages labeled with anti-Iba1 antibody and a few eosinophils and mast cells were observed compared with that in the lesion of FGESF.…”