Unusual Presentation of Feline Leprosy Caused by Mycobacterium lepraemurium in the Alpine Region

Abstract

A 9-year-old cat was referred with multiple, raised, ulcerative and non-ulcerative nodules in the periocular area, sclera and ear-base region, and on the ventral aspect of the tongue. In addition, a progressive ulcerative skin nodule on the tail was observed. Fine-needle aspirations of multiple nodules from the eyelid and sclera revealed the presence of histiocytes with numerous acid-fast intracellular bacilli. The replication of slowly growing mycobacteria in liquid media was detected from biopsied nodules after three months of incubation. The molecular characterization of the isolate identified Mycobacterium (M.) lepraemurium as the cause of the infection. The cat was treated with a combination of surgical excision and a four-week course of antimicrobial therapy including rifampicin combined with clarithromycin. This is an unusual manifestation of feline leprosy and the first molecularly confirmed M. lepraemurium infection in a cat with ocular involvement in Europe. The successful combination of a surgical and antimycobacterial treatment regimen is reported.

Keywords: Mycobacterium lepraemurium; cat; cutaneous mycobacteriosis; feline leprosy; nontuberculous mycobacteria.

Figure 1

Left eye with ulcerative nodular skin lesion on the lower eyelid and non-ulcerative nodule on the dorsolateral sclera (A). Non-ulcerative nodule on the right medial canthus (B). Small non-ulcerative nodules on the ventral aspect of the tongue (C) and in the right ear-base region (D). Progressive ulcerative skin nodule in the distal part of the tail (E).

Figure 2

Cytological fine-needle aspirates of the lesions on the left lower eyelid and the sclera. Mixed inflammatory cell infiltrate consisting of neutrophils and of a large number of macrophages containing numerous intracytoplasmic rod-shaped, partly darkly blue-stained and partly unstained bacteria (A) that were acid-fast in the Ziehl–Neelsen stain (B).

Figure 3

One year after surgical resection of the lesions and six months after discontinuation of the antimicrobials, the cat’s ocular lesions on the left (A) and right eye (B) were considered resolved.