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| | + | |pagetitle =Mycobacterium species |
| | + | |pagebody = *Mycobacteruim organisms belong to the family Mycobacteriaceae, order Actinomycetales. This class of organism includes obligate pathogens, opportunistic pathogens and saprophytes; they can cause chronic, progressive, granulomatous infections including tuberculosis, [[Johne's Disease|Johne's disease]] and feline leprosy. ''M. bovis'', ''M. tuberculosis'' and ''M. avium'' cause [[Respiratory Bacterial Infections - Pathology#Tuberculosis|tuberculosis of cattle]], [[Respiratory Bacterial Infections - Pathology#Tuberculosis in pigs|tuberculosis of pigs]] and [[Respiratory Bacterial Infections - Pathology#Tuberculosis in dogs|tuberculosis of dogs]] respectively. ''Mycobacterium leprae'' and ''M.lepraemurium'' cause human, feline/murine leprosy respectively. Localized opportunistic [[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|skin]] and subcutaneous infection can be caused by saprophytic and rapidly growing atypical mycobacteria. |
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| − | ===Overview===
| + | Environmental species are found in soil, vegetation and water. Mycobacterium organisms are |
| | + | non-motile, non-spore forming weakly Gram-positive acid-fast rods. They require egg-based media for growth, forming slow-growing (three weeks are required for culture) colonies that stain with carbol dyes and resist subsequent decolorization with inorganic acids; this characteristic which is due to the spatial arrangement of mycolic acids within the cell wall makes them acid fast. They are identified by Ziehl-Neelson staining and differentiated by culture, biochemical tests, chromatography and molecular techniques. |
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| − | *Mycobacterial infections are caused by bacteria belonging to the family Mycobacteriaceae, order Actinomycetales
| + | Mycobacterium species are resistant to disinfectants and environmental conditions, but are susceptible to pasteurisation. |
| − | *Includes obligate pathogens, opportunistic pathogens and saprophytes
| + | |contenttitle =Content |
| − | *Cause chronic, progressive, granulomatous infections
| + | |contentbody =<big><b> |
| − | *Cause tuberculosis, [[Intestines Proliferative Enteritis - Pathology#Paratuberculosis (Johnes disease)|Johne's disease]] and feline leprosy
| + | <categorytree mode=pages>Mycobacterium species</categorytree> |
| − | *''M. bovis'', ''M. tuberculosis'' and ''M. avium'' cause [[Respiratory Bacterial Infections - Pathology#Tuberculosis|tuberculosis of cattle]], [[Respiratory Bacterial Infections - Pathology#Tuberculosis in pigs|tuberculosis of pigs]] and [[Respiratory Bacterial Infections - Pathology#Tuberculosis in dogs|tuberculosis of dogs]] respectively
| + | </b></big> |
| − | *The 'classical' tuberculosis lesions are caused by the [[Mycobacterium tuberculosis complex]]
| + | |logo =bugs-logo copy.png |
| − | *The Johne's type lesions are caused by the [[Mycobacterium avium complex]]
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| − | *Environmental species are found in soil, vegetation and water
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| − | *''Mycobacterium leprae'' and ''M.lepraemurium'' cause human, feline/murine leprosy respectively
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| − | *Atypical mycobacteriosis is a localized opportunistic skin and subcutaneous infection caused by saprophytic and rapidly growing atypical mycobacteria
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| − | *Granulomatous lesions in [[Muscles Inflammatory - Pathology#Tuberculosis|muscle]] and [[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|skin]]
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| − | *Skin tuberculosis of cattle causes nodules along the lymphatics of the limbs
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| − | *Bovine farcy is thought to be caused by ''M. senegalense'' and ''M. farcinogenes''
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| − | *Saprophytic mycobacteria cause granulomatous lesions
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| − | ===Characteristics===
| + | [[Category:Bacterial Organisms]] |
| − | | + | [[Category:Gram_positive_bacteria]] |
| − | *Aerobic, weakly Gram-positive acid-fast rods
| + | [[Category:Rods]] |
| − | *Non-motile, non-spore forming
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| − | *Cell walls contain mycolic acid
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| − | *Require egg-based media for growth
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| − | *Slow-growing colonies
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| − | *Resistant to disinfectants and environmental conditions; susceptible to pasteurisation
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| − | *Mycobacteria stain with carbol dyes and resist subsequent decolorization with inorganic acids; this characteristic which is due to the spatial arrangement of mycolic acids within the cell wall makes them acid fast
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| − | ===Identification===
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| − | *Identified by Ziehl-Neelson staining
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| − | *Differentiated by culture, biochemical tests, chromatography and molecular techniques
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| − | *Pathogenic species require at least three weeks for growth on egg-based media
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| − | [[Mycobacterium bovis]]
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| − | [[Mycobacterium avium]]
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| − | [[Mycobacterium lepraemurium]]
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| − | ===[[Intestines Proliferative Enteritis - Pathology#Paratuberculosis (Johnes disease)|Johne's Disease (paratuberculosis)]]===
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| − | *[[Intestines Proliferative Enteritis - Pathology#Paratuberculosis (Johnes disease)|Johne's Disease]] is a chronic, contagious enteritis of ruminants
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| − | *Caused by ''M avium'' subsp. ''paratuberculosis''
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| − | *Epidemiology
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| − | **Transmitted to young calves by ingestion of mycobacteria in faeces of infected adults
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| − | **Organisms viable in environment for long periods
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| − | **Long incubation period with clinical signs appearing in cattle over 2 years of age
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| − | **Subclinical carriers can occur, shedding organisms in their faeces
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| − | *Pathogenesis and pathogenicity
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| − | **''M avium'' subsp. ''paratuberculosis'' is an intracellular pathogen
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| − | **Mycobacteria are ingested by macrophages in the Peyer's patches
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| − | **Survival and replication of mycobacteria in macrophages initiate an immune-mediated granulomatous reaction
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| − | **Lymphocytes and macrophages accumulate in the lamina propria and submucosa, resulting in marked thickening and folding of the intestinal wall
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| − | **Mesenteric lymph nodes are enlarged
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| − | **A protein-losing enteropathy results, along with failure to absorb nutrients and water
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| − | *Clinical signs
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| − | **Diarrhoea, initially intermittent, and weight loss in cattle
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| − | **Weight loss in sheep and goats
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| − | **Rapidly fatal with weight loss and diarrhoea in some deer
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| − | *Diagnosis
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| − | **All diagnostic procedures have faults but include:
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| − | **Microscopy of rectal biopsies
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| − | **Faecal culture
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| − | **Serology of serum including complement fixation tests, agar-gel immunodiffusion test and an ELISA
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| − | **Histopathology of intestines and lymph nodes
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| − | **Isolation and identification of mycobacteria from faeces and tissues
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| − | **Ziehl-Neelson-positive smears
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| − | **Intradermal tuberculin test
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| − | **DNA probes for detection in faeces
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| − | *Control
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| − | **Slaughter of affected animals
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| − | **Detection and slaughter of subclinical shedders using faecal culture, DNA probes and ELISA
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| − | **Good hygiene to protect young calves
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| − | **Separation and isolation of calves from affected dams
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| − | **Inactivated adjuvanted vaccines are available and reduce shedding of mycobacteria but do not eliminate infection
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| − | [[Category:Bacteria]][[Category:Gram_positive_bacteria]][[Category:Rods]] | |