Mycobacterium spp

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Atypical mycobacterial infection in a dog which responded to antimicrobial therapy[1]
Disseminated Mycobacterium spp in a dog with weight loss, diarrhea and ascites
Opportunistic leproid granuloma on the hip of a dog[2]
Pulmonary granuloma from a dog infected with M. tuberculosis, showing numerous acid-fast bacilli (stained bright red), demonstrated by using Ziehl Neelsen staining[3]
Gross pathological changes of the lung and heart observed in a dog which died from M. bovis infection[4]

Mycobacterium spp are a broad group of zoonotic[5] Gram-positive aerobic bacteria which cause dermal, pulmonary and systemic diseases in dogs.

Mycobacteria are widespread saprophytes, but approximately one-third of identified species are also opportunistic pathogens in humans and dogs, associated with skin, soft tissue, bone, and pulmonary infections as well as disseminated disease. Clinical and experimental evidence indicates a major role for the cell-mediated immune response in the pathogenesis of infection[6].

Dog to human and human to dog infections have been reported commonly[7][8], and many affected dogs live a greater proportion outdoors in rural environments. Immunosuppression appears to play a pivotal role in etiopathogenesis in household pets[9].

Species which are pathogenic to dogs include:

  • Mycobacterium tuberculosis complex (zoonotic)
- Mycobacterium tuberculosis[10][11]
- Mycobacterium bovis[12]
- Mycobacterium microti
  • Mycolactone-producing mycobacteria
- Mycobacterium ulcerans
  • Mycobacterium fortuitum clade
- Mycobacterium fortuitum[13]
  • Mycobacterium avium complex
- Mycobacterium avium sub paratuberculosis (paratuberculosis)[14]
- Mycobacterium avium sub hominissuis[15]
- Mycobacterium avium sub intracellulare
  • Mycobacterium chelonae clade
- Mycobacterium chelonae (zoonotic via bite-wounds)[16]
  • Mycobacterium smegmatis clade
- Mycobacterium goodii
- Mycobacterium smegmatis
  • Ungrouped
- Mycobacterium flavescens
- Mycobacterium kansasii[17]
- Mycobacterium vaccae (saprophytic; use as adjuvant in atopy)[18]

Atypical mycobacterial dermatitis

Atypical mycobacteria, caused by M. avium intracellulare-complex which can create a number of different clinical symptoms including scale, draining nodules and hair loss.

The primary routes of exposure in dogs and cats to 'atypical' mycobacteria are direct contact or ingestion of organisms from soil, water, or animal carcasses or feces; aerosolized transmission is considered less common. All species of non-tuberculous mycobacteria are considered of low virulence, typically causing severe disease only in immunosuppressed individuals.

Leproid granuloma syndrome

Canine leproid granuloma syndrome was coined to describe a nodular pyogranulomatous disease affecting the skin and subcutis of dogs[19] and affects principally short-coated breeds[20].

With M. ulcerans, M. fortuitum, M. goodii and M. smegmatis infections, lesions are usually confined to the skin, with leprosy-like dermal ulcers and panniculitis[21][22].

Infections often involve single or multiple nodules, usually on the head and especially on the dorsal fold of the ears, but the cervicothoracic region, dorsum or flank are also affected. Patients are often systemically well, although fever, local pain and lameness may be noted.

The pathology of canine leproid granuloma syndrome is highly uniform and is suggestive of saprophytic mycobacterial involvement[23]. Histopathological findings include nodular to diffuse pyogranulomatous, lymphoplasmocytic inflammatory infiltrates, with or without necrosis, localized in the dermis or subcutaneous tissue.

Diagnosis of leproid granuloma is based on microbial culture[24] or PCR assays, which is usually required, particularly for those mycobacteria which are nonculturable or difficult to culture[25][26][27].

Disseminated tuberculosis

While uncommon in both dogs and cats, historical data suggests that dogs are more likely to be infected with M. tuberculosis following exposure to infected humans, while cats were more likely to be infected with M. bovis with exposure assumed to be related to the consumption of contaminated animal products[28].

Clinical findings in dogs infected with M. tuberculosis include anorexia, weight loss, vomiting[29] and leukocytosis[30]. Radiography usually reveals pleural and pericardial effusion, ascites, and hepatomegaly[31].

Disseminated pulmonary infections involve mediastinal lymphadenopathy[32] and calcospherite-like bodies and caseous necrosis of the trachea[33] and pulmonary parenchyma, with formation of tubercle-like granulomas in lungs and, rarely, the liver[34] and brain[35]. Generalized peritonitis has also been reported with M. microti[36].

Chronic cases may be associated with hypertrophic osteoarthropathy[37].

As with Escherichia coli, nitric oxide-resistant Mycobacterium spp have been associated with poor outcomes[38].

Treatment

Treatment of localized lepromatous-like infections involves a combination of surgical debridement and medical therapy with drugs such as doxycycline and ciprofloxacin[39].

Prolonged antibacterial therapy is required for disseminated infections with drugs such as clarithromycin[40], moxifloxacin[41], ciprofloxacin[42], pradofloxacin[43], clofazimine, rifampicin and dapsone[44].

References

  1. Animal dermatology
  2. Medical dictionary
  3. Parsons SD et al (2008) Pulmonary Mycobacterium tuberculosis (Beijing strain) infection in a stray dog. J S Afr Vet Assoc 79(2):95-98
  4. Shrikrishna, D et al (2009) Human and canine pulmonary Mycobacterium bovis infection in the same household: re-emergence of an old zoonotic threat? Thorax 64:89-91
  5. Posthaus H et al (2011) Accidental infection of veterinary personnel with Mycobacterium tuberculosis at necropsy: a case study. Vet Microbiol 149(3-4):374-380
  6. Howard ST & Byrd TF (2000) The rapidly growing mycobacteria: saprophytes and parasites. Microbes Infect 2(15):1845-1853
  7. Erwin PC et al (2004) Mycobacterium tuberculosis transmission from human to canine. Emerg Infect Dis 10(12):2258-2210
  8. Hackendahl NC et al (2004) Putative transmission of Mycobacterium tuberculosis infection from a human to a dog. J Am Vet Med Assoc 225(10):1573-1577
  9. Bryden SL et al (2004) Mycobacterium goodii infection in a dog with concurrent hyperadrenocorticism. Vet Dermatol 15(5):331-338
  10. Une Y & Mori T (2007) Tuberculosis as a zoonosis from a veterinary perspective. Comp Immunol Microbiol Infect Dis 30(5-6):415-425
  11. Parsons SD et al (2012) Detection of Mycobacterium tuberculosis infection in dogs in a high-risk setting. Res Vet Sci 92(3):414-419
  12. LoBue PA et al (2010) Tuberculosis in humans and animals: an overview. Int J Tuberc Lung Dis 14(9):1075-1078
  13. Irwin PJ et al (2000) Acute bronchopneumonia associated with Mycobacterium fortuitum infection in a dog. Aust Vet J 78(4):254-257
  14. Glanemann B et al (2008) Detection of Mycobacterium avium subspecies paratuberculosis-specific DNA by PCR in intestinal biopsies of dogs. J Vet Intern Med 22(5):1090-1094
  15. Haist V et al (2008) Mycobacterium avium subsp. hominissuis infection in 2 pet dogs, Germany. Emerg Infect Dis 14(6):988-990
  16. Stelzmueller I et al (2005) Mycobacterium chelonae skin infection in kidney-pancreas recipient. Emerg Infect Dis 11(2):352-354
  17. Pressler BM et al (2002) Isolation and identification of Mycobacterium kansasii from pleural fluid of a dog with persistent pleural effusion. J Am Vet Med Assoc 220(9):1336-1340
  18. Ricklin Gutzwiller ME et al (2007) Intradermal injection of heat-killed Mycobacterium vaccae in dogs with atopic dermatitis: a multicentre pilot study. Vet Dermatol 18(2):87-93
  19. Hughes MS et al (2000) Identification by 16S rRNA gene analyses of a potential novel mycobacterial species as an etiological agent of canine leproid granuloma syndrome. J Clin Microbiol 38(3):953-959
  20. Malik R et al (1998) Mycobacterial nodular granulomas affecting the subcutis and skin of dogs (canine leproid granuloma syndrome). Aust Vet J 76:403–407
  21. Malik R et al(2004) Infections of the subcutis and skin of dogs caused by rapidly growing mycobacteria. J Small Anim Pract 45(10):485-494
  22. Krimer PM et al (2010) Panniculitis attributable to Mycobacterium goodii in an immunocompetent dog in Georgia. J Am Vet Med Assoc 237(9):1056-1059
  23. Charles J et al (1999) Cytology and histopathology of canine leproid granuloma syndrome. Aust Vet J 77(12):799-803
  24. Twomey LN et al(2005) A "down under" lesion on the muzzle of a dog. Vet Clin Pathol 34(2):161-163
  25. Hughes MS et al (1997) Determination of the etiology of presumptive feline leprosy by 16S rRNA gene analysis. J Clin Microbiol 35:2464–2471
  26. Naughton JF et al(2005) Systemic Mycobacterium avium infection in a dog diagnosed by polymerase chain reaction analysis of buffy coat. J Am Anim Hosp Assoc 41(2):128-132
  27. Conceição LG et al (2011) Epidemiology, clinical signs, histopathology and molecular characterization of canine leproid granuloma: a retrospective study of cases from Brazil. Vet Dermatol 22(3):249-256
  28. Birn KJ et al (1965) Canine tuberculosis. Vet Rec 77:1341–1342
  29. Horn B et al (2000) Disseminated Mycobacterium avium infection in a dog with chronic diarrhoea. Aust Vet J 78(5):320-325
  30. Turinelli V et al (2004) Mycobacterium tuberculosis infection in a dog from Africa. Vet Clin Pathol 33(3):177-181
  31. Wilkins MJ et al (2008) Absence of Mycobacterium bovis infection in dogs and cats residing on infected cattle farms: Michigan, 2002. Epidemiol Infect 136(12):1617-1623
  32. Campora L et al (2011) Mycobacterium avium subspecies hominissuis disseminated infection in a Basset Hound dog. J Vet Diagn Invest 23(5):1083-1087
  33. Bauer NB et al (2004) Calcospherite-like bodies and caseous necrosis in tracheal mucus from a dog with tuberculosis. Vet Clin Pathol 33(3):168-172
  34. O'Toole D et al (2005) Fatal mycobacteriosis with hepatosplenomegaly in a young dog due to Mycobacterium avium. J Vet Diagn Invest 17(2):200-204
  35. Fuente CD et al (2012) Imaging diagnosis- magnetic resonance imaging findings of an intracranial epidural tuberculoma in a dog. Vet Radiol Ultrasound Jun 15
  36. Deforges L et al (2004) First isolation of Mycobacterium microti (Llama-type) from a dog. Vet Microbiol 103(3-4):249-253
  37. Lenehan, TM & Fetter, AW (1985) Hypertrophic osteopathy, in: C.D Newton, D.M. Nunamaker (Eds.), Textbook of Small Animal Orthopaedics, JB Lippincott Co, Philadelphia, PA. pp:597–601
  38. Santos PL et al (2012) Leishmania chagasi naturally resistant to nitric oxide isolated from humans and dogs with visceral leishmaniasis in Brazil. Nitric Oxide 27(1):67-71
  39. Bryden SL et al (2004) Mycobacterium goodii infection in a dog with concurrent hyperadrenocorticism. Vet Dermatol 15(5):331-338
  40. Wallace RJ et al (1993) Clinical trial of clarithromycin for cutaneous (disseminated) infection due to Mycobacterium chelonae. Ann Intern Med 119:482–486
  41. Govendir M et al (2011) Susceptibility of rapidly growing mycobacteria isolated from cats and dogs, to ciprofloxacin, enrofloxacin and moxifloxacin. Vet Microbiol 147(1-2):113-118
  42. Jang SS & Hirsh DC (2002) Rapidly growing members of the genus Mycobacterium affecting dogs and cats. J Am Anim Hosp Assoc 38(3):217-220
  43. Govendir M et al (2011) Susceptibility of rapidly growing mycobacteria and Nocardia isolates from cats and dogs to pradofloxacin. Vet Microbiol 153(3-4):240-245
  44. Malik R et al (2013) Ulcerated and nonulcerated nontuberculous cutaneous mycobacterial granulomas in cats and dogs. Vet Dermatol 24(1):146-153
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