Histological and genotypical characterization of feline cutaneous mycobacteriosis: a retrospective study of formalin‐fixed paraffin‐embedded tissues

Abstract

Twenty-nine cases presumptively diagnosed as feline cutaneous mycobacteriosis were evaluated microscopically with haematoxylin and eosin and modified Fite's stained sections using archived formalin-fixed paraffin-embedded tissue specimens. Lesions were characterized histologically as feline leprosy (7 cases lepromatous and 16 cases tuberculoid) or atypical mycobacteriosis (3 cases); three cases did not fit these criteria and were classified as 'miscellaneous'. Actinomycetales-specific polymerase chain reaction (PCR) of variable regions 1, 2 and 3 of the 16S ribosomal RNA (rRNA) gene and subsequent sequence analysis of the amplicons were performed to identify the species of mycobacteria associated with each case. Together, this study identified 10 different Actinomycetales organisms with greater than 98% nucleotide sequence identity to named species, nine were of the genus Mycobacterium and eight were associated with feline leprosy (both lepromatous and tuberculoid). Based on this study, we conclude that feline cutaneous mycobacteriosis should be considered as a syndrome with varied clinical and histological presentations associated with a variety of different Mycobacterium species, organisms other than Mycobacterium sp. may be associated with feline cutaneous mycobacteriosis lesions, and molecular diagnostic techniques can be an important tool for identifying agents associated with lesions of feline cutaneous mycobacteriosis.

Molecular Characterization of a Novel Fastidious Mycobacterium Causing Lepromatous Lesions of the Skin, Subcutis, Cornea, and Conjunctiva of Cats Living in Victoria, Australia

“…Cats are an excellent sentinel species for environmentally acquired infections, as they have a finite geographical range (4,20). It is therefore highly likely that Mycobacterium sp.…”

“…With one exception, culture from all Australian feline leprosy cases had been unsuccessful, de-spite the use of a range of appropriate media and the presence of abundant AFB in most specimens. Recent work from North America has indicated that additional, closely related mycobacterial taxa (belonging to a species provisionally called "M. visibilis"; later corrected to "M. visibile") also cause disseminated skin disease in cats (2,4,8).…”

Ulcerated and Nonulcerated Nontuberculous Cutaneous Mycobacterial Granulomas in Cats and Dogs

“…[9][10][11][12][13] Cases occur worldwide, although certain mycobacterial species have strong geographical predilections. Critically, FLS lesions cannot be distinguished clinically or microscopically from lesions caused by tuberculosis bacteria (Mycobacterium bovis and Mycobacterium microti) and members of Mycobacterium avium complex (MAC).…”

“…Canine leproid granuloma (CLG) [1][2][3][4][5][6][7][8] and the feline leprosy syndromes (FLS) [9][10][11][12][13] are relatively uncommon nodular dermatoses caused by species of saprophytic mycobacteria that are extremely fastidious and generally uncultivable in the laboratory. Infection may be self-limiting, particularly in dogs with CLG, 2 although it is impossible to predict which cases will have lesions that regress spontaneously.…”

Comparison of Three Immunodiagnostic Assays for Antemortem Detection of Mycobacterium Bovis Stimulation in Domestic Cats

“…8,19 Antemortem diagnosis of M. bovis infection within cattle uses the tuberculin skin test, the single intradermal comparative tuberculin test, and the gamma interferon assay; however, skin testing is reportedly inconsistent when used in domestic cats. 4,5,11,13,14,19,24 In an effort to increase sensitivity and specificity in antemortem assays, laboratories have expanded their research to include both cellmediated and humoral immune responses with diagnostic tests such as enzyme-linked immunosorbent assay (ELISA), multiple antigen print immunoassay (MAPIA), and rapid test. The most recent immunodiagnostic tests developed for cats are the gamma interferon (IFN-c) ELISA and enzymelinked immunospot (ELISPOT) assay.…”