Pulmonary Mycobacterium bovis infection in a dog

dAim: To describe the clinical course of a dog infected with Mycobacterium bovis causing a granulomatous pneumonia.

dClinical findings: The dog initially presented with a persistent cough, inappetence and weight loss. Clinical findings included a fever, dyspnoea and tachypnoea, with haematological evidence of a mild neutrophilia and hypoalbuminaemia. Radiographs of the chest demonstrated a concomitant pneumothorax, pleural effusion, and a consolidated area within the left caudal lung lobe. An exploratory thoracotomy revealed this to be a ruptured granulomatous lesion. Subsequent histopathological, microbiological and genetic studies identified M. bovis as the causal agent.

dClinical significance: Mycobacterium bovis infections should be included in the differential diagnosis of pulmonary disease and pleural effusions in dogs living in regions of New Zealand known to have a high incidence of mycobacterial infection in wildlife and farm animals.     

Mycobacterium fortuitum abortion in a sow

Two aborted Chester White pig fetuses were presented to a veterinary diagnostic laboratory in Illinois. Postmortem examination identified no gross abnormalities. Histologic evaluation revealed multifocal necrosis of chorionic epithelial cells, coalescing areas of mineralization in the placenta, and focal accumulations of viable and degenerate neutrophils in the lung. Intra- and extracellular acid-fast bacilli were identified in the lesions in both the placenta and lungs. Bacterial culture of stomach contents yielded heavy growth of Mycobacterium fortuitum, a rapidly growing nontuberculous mycobacterium (NTM), which was further confirmed through whole-genome sequencing. NTM are opportunistic pathogens commonly found in the soil and in contaminated water supplies. In animals, M. fortuitum is typically introduced through cutaneous wounds leading to infections limited to the skin, with systemic infection being uncommon. To our knowledge, abortion caused by M. fortuitum has not been reported previously.     

Experimental Reproduction of Feline Mycobacterium fortuitum Panniculitis

Resumen— Con el fin de lograr un modelo experimental de la infección por Mycobacterium fortuitum, causante de paniculitis en condiciones naturales en el gato, se inoculóM. fortuitum en el cojinte plantar de ratones o en el tejido adiposo inguinal de conejos y gatos. Los ratones manifestaron una dermatitis crónica y una linfadenitis granulomatosa necrotizante con localizatión intracelular del microorganismo. Los conejos manifestaron inflamaciones granulomatosas supurativas necrotizantes con microrganismos en vacuolas adiposas rodeadas por heterófilos macrófagos epitelioides y/o zonas de necrosis. Los cinco gatos adultos y una de las tres crias mostraron fistulas supurativas, úlceras puntuales o nódulos en el paniculo adiposo de la zona inguinal. La lesión en la región inguinal de estos seis animales consistia en una paniculitis granulomatosa; las otras dos crias presentaban una paniculitis piogranulomatosa necrotizante. Se identificaron bacilos en los cortes histológicos teñidos con Hematoxilina y Eosina en cuatro gatos adultos y en una de las crias. Se aislóMycobacterium fortunitum a partir del tejido adiposo en todos los gatos adultos y en una de las tres crias. La inoculación de 1.4 × 10¹⁰M.fortuitum en el tejido adiposo subcutáneo inguinal en los gatos con grandes masas grasas en esas zonas causó una infección microbacteriana idéntica a la enfermedad felina en condiciones naturales. [Lewis, D. T., Hodgin, E. C, Foil, C. S., Cox, H. U., Roy, A. F., Lewis, D. D. Experimental reproduction of feline Mycobacterium fortuitum panniculitis. (Reproductión experimental de la paniculitis felina por Mycobacterium fortuitum). Abstract— In order to establish an animal model of the naturally occurring feline Mycobacterium fortuitum panniculitis an inoculum of M. fortuitum organisms was injected into the hindlimb footpad of mice or subcutaneous fat of the inguinal area of rabbits and cats. Mice developed chronic dermatitis and necrotizing granulomatous lymphadenitis with intracellular localization of the organism. Rabbits developed necrotizing suppurative granulomatous inflammation with organisms in heterophil-lined fat vacuoles, epithelioid macrophages and/or necrotic areas. All five adult cats and one of three kittens developed draining tracts, punctate ulcers or nodules in the panniculus adiposus of the inguinal area. A pyogranulomatous panniculitis characterized the inguinal region in these six animals; a necrotizing pyogranulomatous panniculitis was present in the remaining two kittens. Rod-shaped bacilli were present on hematoxylin and eosin stained tissue sections in four adult cats and one kitten. Mycobacterium fortuitum was isolated from the inguinal subcutaneous fat in all five adult cats and one of three kittens. Injection of 1.4 × 10¹⁰M. fortuitum organisms into the subcutaneous fat of the inguinal area of cats with extensive inguinal fatpads produced a mycobacterial infection identical to the naturally occurring feline disease.     

Cutaneous granulomas associated with Mycobacterium fortuitum infection in a cat

Feline mycobacterial skin infections are reviewed briefly. A case of skin granulomas in a cat associated with the presence of the fast–growing acid–fast bacillus, Mycobacterium fortuitum , is reported. Surgical excision was followed by recurrence, but resolution of the lesions was obtained by tetracycline therapy for 12 weeks interspersed with a 14–day course of choloramphenicol. An attempt at experimental transmission to a kitten was unsuccessful. The characteristics of the fast–growing mycobacteria and the possible sources of infection are discussed.     

Mycobacterium goodii infection in a dog with concurrent hyperadrenocorticism

Abstract A 9-year-old Boston terrier was diagnosed with multifocal, nodular panniculitis caused by an organism belonging to the Mycobacterium smegmatis group by histological evaluation and bacteriological identification. The mycobacterial species was identified by direct gene sequence analysis and confirmed to be Mycobacterium goodii. Treatment using doxycycline and ciprofloxacin was successfully implemented for the mycobacterial panniculitis over a period of 9 months. Concurrent pituitary-dependent hyperadrenocorticism (Cushing's disease) was also identified using routine diagnostic methods and mitotane therapy was implemented. There was follow-up for 14 months after cessation of antimicrobial therapy with no recurrence of mycobacterial infection. Although cutaneous infections are frequently recognized as complications of canine pituitary-dependent hyperadrenocorticism, concurrent mycobacterial panniculitis due to any rapidly growing mycobacterium has not previously been reported. This is the first confirmed case of mycobacterial panniculitis due to M. goodii infection in a dog and also the first of any rapidly growing mycobacterial infection in a dog with concurrent endogenous Cushing's disease.     

Mycobacterium tuberculosis infection in a dog from Africa

A 4-year-old male Boxer dog with a history of vomiting, diarrhea, and weight loss moved from West Africa to Lyon, France, where it was further evaluated. Radiographs revealed pleural effusion and enlargement of tracheobronchial lymph nodes and liver. Cytologic examination of the pleural effusion and a fine needle aspirate specimen of the liver showed mixed mononuclear inflammation with nonstaining rod structures within epithelioid histiocytes. At necropsy, the main gross pathologic findings were exudative pleuritis, nodular hepatitis, and infarcts and caseous nodules in the kidneys. The main histologic lesions were granulomatous hepatitis, granulomatous pneumonia, fibrinous leukocytic pleuritis, necrotic and fibro-calcified granulomatous lymphadenitis, and granulomatous nephritis. A Ziehl-Neelsen stain applied to both cytologic and histologic samples was positive for acid-fast bacilli. Bacterial culture of the pleural fluid was positive for Mycobacterium tuberculosis. Cytology is a valuable tool in the diagnosis of this important zoonotic disease.     

Disseminated Mycobacterium avium infection in a dog with chronic diarrhoea

A 3-year-old Maltese-cross dog presented with a 4-month history of chronic diarrhoea and inappetence. Poorly regenerative anaemia, leukocytosis and hypoproteinaemia were evident on several occasions. Biopsies of stomach, duodenum and colon revealed marked infiltration of mucosae by macrophages containing many acid-fast bacilli. Similar organisms were numerous in a faecal smear. Melaena, hematochezia and severe abdominal pain developed and were unresponsive to therapy. Following euthanasia and necropsy, histiocytic cells containing acid-fast bacilli were found throughout the gastrointestinal tract, mesenteric and peripheral lymph nodes, spleen, liver, kidney and lungs. The organism was identified as Mycobacterium avium by bacterial culture and polymerase chain reaction testing.     

Systemic infection of Mycobacterium avium subspecies hominissuis and fungus in a pet dog

A 3-year-old neutered female poodle with a long history of dermatophytic skin disease was presented with lethargy, anorexia and progressive weight loss. Abdominal ultrasonography revealed markedly enlarged mesenteric lymph nodes and multiple hypoechoic foci in the spleen. Cytology of the mesenteric lymph nodes and spleen showed granulomatous inflammation with fungal organisms and negatively stained intracytoplasmic bacterial rods consistent with Mycobacteria spp. Based on culture, multiplex polymerase chain reaction and sequence analysis, the bacterium was identified as Mycobacterium avium subspecies hominissuis. Despite treatment with antibiotics, the dog’s condition deteriorated, and it died approximately 3 weeks after first presentation.     

Survival of a dog with pneumonia caused by Mycobacterium fortuitum

Pneumonia caused by Mycobacterium fortuitum was diagnosed in the left lung lobes of a 3-year-old male Samoyed. Unilateral pneumonectomy and antibiotic treatment (primarily amoxicillin trihydrate-clavulanate potassium and kanamycin) were associated with resolution of the pneumonia. In dogs, M fortuitum causes pulmonary disease that radiographically resembles bacterial pneumonia. Therefore, M fortuitum infection should be considered in dogs with radiographic signs of bronchopneumonia that worsen despite antibiotic treatment.     

Pyogranulomatous panniculitis in a cat associated with infection by the Mycobacterium fortuitum/peregrinum group

A 6-year-old, spayed female, American domestic shorthair was presented with a 10-month history of nodules on the dorsum. Diagnosis of pyogranulomatous panniculitis caused by Mycobacterium fortuitum/peregrinum group was achieved by using tissue culture, chromatography, and histopathologic examination. Pathological findings, diagnosis, and clinical management of the condition are discussed.     

Tuberculosis caused by Mycobacterium bovis infection in a donkey

Mycobacterial infections are rare in equines. Mycobacterium bovis (M. bovis) is an important zoonotic bacterial pathogen causing disease in a wide range of animal species and sporadically causes severe disseminated disease in horses. This report describes the clinical, gross post‐mortem examination and histopathological findings in a case of disseminated M. bovis infection in a donkey which to the authors’ knowledge has not been previously documented in the scientific literature.     

Diagnostic and public health investigation of Mycobacterium tuberculosis infection in a dog in Ontario,Canada

A 4-y-old, female mixed-breed dog was presented to the Ontario Veterinary College for further evaluation of multiple pulmonary and hepatic masses, intrathoracic lymphadenitis, and recent development of a pyogranulomatous pleural effusion. Along with other comprehensive tests, a thoracic lymph node biopsy was performed, and Mycobacterium tuberculosis complex infection was confirmed by real-time PCR. The dog’s condition declined post-operatively, and euthanasia was elected. Postmortem examination confirmed severe granulomatous pneumonia, hepatitis, intrathoracic and intraabdominal lymphadenitis, omentitis, and nephritis. Line-probe assays performed on samples collected postmortem confirmed the species as M. tuberculosis. 24-loci MIRU-VNTR genotyping, spoligotyping, and whole-genome sequencing revealed relations to known human isolates, but no epidemiologic link to these cases was investigated. Given the concern for potential human exposure during this animal’s disease course, a public health investigation was initiated; 45 individuals were tested for M. tuberculosis exposure, and no subsequent human infections related to this animal were identified. Our case highlights the need for more readily available, minimally invasive testing for the diagnosis of canine mycobacteriosis, and highlights the ability of canid species to act as potential contributors to the epidemiology of M. tuberculosis infections.     

Mycobacterium fortuitum infection interference with Mycobacterium bovis diagnostics: natural infection cases and a pilot experimental infection

Mycobacterium fortuitum and at least 1 unidentified species of soil mycobacteria were isolated from lymph nodes from 4 of 5 African buffalo (Syncerus caffer) that had been culled because of positive test results using the Bovigam assay. The buffalo were part of a group of 16 free-ranging buffalo captured in the far north of the Kruger National Park (South Africa) assumed to be free of bovine tuberculosis. No Mycobacterium bovis was isolated. To investigate the possible cause of the apparent false-positive diagnosis, the Mycobacterium isolates were inoculated into 4 experimental cattle and their immune responses monitored over a 13-week period, using the gamma interferon assay. The immune reactivity was predominantly directed toward avian tuberculin purified protein derivative (PPD) and lasted for approximately 8 weeks. During that period 3 of 4 cattle yielded positive test results on 1 or 2 occasions. The immune responsiveness was boosted when the inoculations were repeated after 15 weeks, which led to 2 subsequent positive reactions in the experimental animal that did not react previously. Including an additional stimulatory antigen, sensitin prepared from M. fortuitum in the gamma interferon assay, showed that it was able to elicit a detectable gamma interferon response in all 4 experimentally inoculated cattle when applied in parallel with bovine and avian tuberculin PPD for the stimulation of blood samples. The implications of occasional cross-reactive responses in natural cases of infection with environmental mycobacteria in the diagnosis of bovine tuberculosis in African buffalo and cattle in South Africa are discussed.     

Mycobacterium avium infection in a dog

A 5-year old, spayed, mongrel was presented with intractable diarrhoea. Histopathologic examination of biopsy specimens taken during exploratory laparotomy revealed acid-fast organisms in the spleen, caecum, and colon. The dog was subsequently destroyed. At post-mortem, lesions were also observed in the liver and lymph nodes. Mycobacterium avium was cultured from splenic tissue. Infection of dogs with this organism is rare and the clinical picture described unusual.