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