Determination of the etiology of presumptive feline leprosy by 16S rRNA gene analysis

Abstract

PCR-amplified 16S rRNA gene sequences were obtained directly from tissue specimens from eight cats with presumptive feline leprosy. Acid-fast bacilli were observed in sections from all eight specimens, but culture for mycobacteria was successful for one specimen only. Analysis of the V2 variable region of each 16S rRNA PCR product identified a sequence with 100% nucleotide identity to the sequences of Mycobacterium lepraemurium, Mycobacterium avium, and Mycobacterium paratuberculosis in four of the specimens from cats with feline leprosy. Separate M. paratuberculosis-and M. avium-specific PCR amplifications of the four specimens were negative, thus substantiating the identification of M. lepraemurium in these specimens from cats with feline leprosy. Further sequence analysis of the V3 variable region of one of the four specimens provided conclusive evidence of the presence of M. lepraemurium. This is the first report of the definitive identification of M. lepraemurium in cats with feline leprosy by molecular biology-based analyses. M. avium, which is rarely reported in cats, and Mycobacterium chitae, a reported nonpathogenic, rapidly growing mycobacterial species found in the environment, were identified in the specimen from which acid-fast bacilli were cultured. Two of the specimens from cats were infected with a potentially novel species of mycobacteria which had a 16S rRNA gene sequence sharing the closest nucleotide sequence identity with that of Mycobacterium malmoense. Molecular biologybased analyses provided for the accurate and rapid diagnosis of mycobacterial infections in cats and circumvented the problems of culture and misdiagnosis of feline leprosy associated with traditional methods.

Isolated lepromatous conjunctivo‐corneal granuloma in a cat from Italy

“…18 The causative agent is presumed to be M. lepraemurium ; however, recent studies using the polymerase chain reaction (PCR) have recently demonstrated the presence of other mycobacteria including novel species. 9,10,19,20 A case of feline leprosy involving a 2-year-old-male cat with a solitary lesion of the right forelimb was described in Northern Italy in 1996. 17 The precise, natural transmission of feline leprosy is unknown, but it has been related to bites of infected rats and cats.…”

Autochthonous feline leprosy caused by Mycobacterium sp. strain Tarwin affecting a cat from the Central Coast of New South Wales

“…16 Although the tissue was submitted to a reference laboratory, culture was not attempted because it has failed to identify a mycobacterial organism in most feline leprosy cases evaluated to date. 4 This is in contrast to other cutaneous mycobacterial diseases of cats caused by M. ulcerans, M. avium, members of the M. tuberculosis complex (M. bovis and M. microti) or rapidly growing mycobacteria, for which tissue culture permits identification of the species and, most importantly, subsequent in vitro antimicrobial susceptibility testing.…”

“…Recently, methanol-fixed and DiffQuik-stained smears of FNA samples diagnosed cytologically with mycobacterial infection have been used to amplify DNA in cases of NSB or AFB being abundant in dogs and cats. 23 PCR testing can help distinguish the different potential mycobacterial pathogens 1,3,4,24 and closely related infectious agents such as Nocardia spp. 25 Definitive diagnosis requires differentiation of the Mycobacterium spp., because treatment will depend on the mycobacterial agent involved, even if it has not been well defined by the peer-reviewed literature.…”

“…F eline leprosy syndrome (FLS) refers to a disease characterised by cutaneous and/or subcutaneous granulomas or pyogranulomas associated with non-cultivable mycobacteria, sometimes with internal organ involvement. [1][2][3][4] In Australia, three species of Mycobacterium have been implicated, including Mycobacterium lepraemurium, the so-called 'novel East Coast mycobacteria species' and its variants, and M. sp. strain Tarwin (M. sp.…”

“…Clinical and microscopic features alone cannot be used to distinguish the different cutaneous mycobacterial diseases. 3,4 Clinical characteristics such as the location and number of nodules present, species of host involved, place of domicile and the histological features (tuberculoid vs lepromatous inflammatory response) in conjunction with the size and morphology of the acid-fast bacilli (AFB) assist the clinician in determining which organism is more likely to be involved.…”