Successful Treatment of Disseminated Nocardiosis Caused by Nocardia veterana in a Dog

Abstract

A 5‐year‐old male castrated Lhasa Apso cross was evaluated for a 1‐month history of inappetence, lethargy, gagging, and progressive right thoracic limb lameness. Synovial fluid analysis revealed nonseptic suppurative inflammation, and a diagnosis of immune‐mediated polyarthritis (IMPA) was made. After 3 months of treatment with prednisone and later cyclosporine, the dog developed multiple firm cutaneous and subcutaneous masses and a focal mass within the jejunum. Cultures of blood, urine, skin lesions, and the jejunal mass identified Nocardia veterana by matrix‐absorption laser desorption ionization‐time‐of‐flight mass spectrometry (MALDI‐TOF MS) and allowed for earlier identification of the organism compared to more traditional secA1 gene sequencing. Immunosuppressive drug treatment was discontinued, and the dog was treated for 3 months by administration of trimethoprim‐sulfamethoxazole (TMS). No recurrence of clinical signs was reported 1 year later. This case report highlights the clinical utility of MALDI‐TOF MS, particularly for the rapid identification of slow‐growing, fastidious organisms.

Molecular Characterization and Antimicrobial Susceptibilities of Nocardia Species Isolated from the Soil; A Comparison with Species Isolated from Humans

“…species are found everywhere from sludge and soil to contaminated soil water, deep-sea sediments [ 1 ], and desert habitats [ 2 ]. Some even infect plants and animals [ 3 , 4 , 5 ]. They are among the most predominant Actinobacteria of the soil microbiota, including that of the extreme biosphere [ 6 ].…”

“…Although they cause a number of severe invasive diseases [ 3 , 13 ], the members of Nocardia spp. are mainly opportunistic pathogens in humans, usually affecting the lungs, central nervous system, and skin [ 14 , 15 ].…”

Successful Treatment of Cutaneous Curvularia geniculata, Nocardia niigatensis, and Viral Papillomatosis in a Dog During the Therapeutic Management of Immune-Mediated Hemolytic Anemia

“…In our case, MALDI-TOF MS identified the cultured Gram-positive branching bacilli as Streptomyces spp; invasive Streptomyces infections are uncommon in animals and are sometimes considered to be contaminants (7). To confirm the MALDI-TOF MS bacterial identification results in our dog, 16S rRNA gene sequencing was performed on the bacterial isolate and revealed Nocardia niigatensis ; 16S rRNA gene sequencing is commonly used for Nocardia identification as the 16S rRNA gene is highly conserved among Nocardia species (1). Identification of the Nocardia species as the causative pathogen, involved in our patient's skin lesions, is important because it allows different options for an effective systemic antimicrobial therapy.…”

“…in dogs have been associated with ciclosporine administration (1, 13). Nocardiosis can be difficult to diagnose due to the relatively slow growth of the organism and possible contaminants from tissue samples (1, 13). We removed the superficial part of the skin biopsy tissue to avoid surface skin contaminants in the culture in our dog.…”

“…Opportunistic infections represent a major cause of mortality in immunocompromised patients and are becoming more prevalent with the increased use of single and multi-agent immunosuppressive medications for treatment of immune-mediated and autoimmune diseases. Reports of opportunistic cutaneous infections in dogs associated with immunosuppression include Nocardia species (1), saprophytic fungi (phaeohyphomycosis and hyalohyphomycosis) (2, 3) and viral-induced papillomas (4, 5). Discontinuation of immunosuppressive medications is recommended with the development of opportunistic infections, which may cause a relapse or worsening of the immune-mediated disease (3, 6).…”