Mycobacterium Flashcards
Mycobacterium: general
Gram (+), acid fast positve
discovered by Robert Koch
contain mycolic acid
Mycolic acids assists in
Acid fast staining
drug, chemical, environment resistance
immunomodulating activities
prevent phagocytic killing
Types of acid fast stain
Ziehl-Neelson
Kinyons
Auramine Rhodamine
The majority of mycobacterium are ___ pathogens
Opportunistic
Can ID mycobacterium by
growth patterns
Biochemical patterns
total cell fatty acid analysis
nucleic acid detection/PCR
Virulence factors
Mycolic acid containing cell wall lipids- surviving in macrophages, stimulate cytokine prod., immunomodulating effects
Cell protein antigens- do not play big role in disease
Exception to Cell protein antigen being pathogentic
M. ulcerans- mycolactone/macrolide toxins
Main reservoir of M. tuberculosis
Humans
Multi-drug resistant TB is resistant to at least
Isoniazid and rifampin
cause of zoonotic TB is
M. bovis
M. bovis: transmission
ingestion, inhalation, possibly by mucous membranes and broken skin
Main portal of entry is GIT
T or F
M. bovis has long survival term in environment
False
only survives a few weeks outside host
Other species with high prevalence of M. bovis
Cervids, badgers in UK, Feral brush tail possums in New zealand
M. bovis: clinical signs
Signs vary greatly, enlarged regional lymph nodes, Cachexia, pulmonary forms with chronic cough
TB in humans was known as
Consumption
M. bovis: pathogenesis
pyogranulomatous lesions in any organ
bacilli are phagocytosed by macrophages, casenous necrosis in center of lesion
casenous lesions of necrosis are surrounded by ___
multinucleated giant cells (Langhan’s cells)
Granulomas form as a result of ___ ____ immune response
Cell-mediated immune response- tubercle
Common later stage lesions are called
tuberculosis cavitary lesions
M. bovis: diagnostic tests
Tuberculin hypersensitivity skin lesions
Caudal fold tuberculin test
comparative cervical tuberculin skin test
interferon gamma release assay, necropsy, imaging, culture
M. Bovis: treatment
not practical or efficacious
anti-tubercular drugs
single drugs use is limited
Elements of bovine TB eradication programs
disease surveillance, pre and post moving test, cull positive animals, wildlife control
Mycobacterium leprae causes
Leprosy or Hansen’s disease
Only known reservoir for M. leprae is ___
nine-banded armadillo
Paucibacillary
Tuberculoid leprosy, few AFB
cell mediated immune response, small number of bacteria
Multibacillary
Lepromatous leprosy
no cell mediated response, severe disease with numerous AFB
Leprosy general features
Chronic granulomatous debilitating disease
numbing skin lesions, nerve thickening, tissue sloughing
Leprosy transmission
nasal secretions
M. lepraemurium
Feline and murine leprosy
M. lepraemurium: pathology
Granulomatous Dermatitis Panniculitis
single or multiple SQ nodules and ulcerated lesions
fastidious organism (hard to culture)
M. lepraemurium: diagnosis
Direct staining- Geimsa or acid fast
culture, biopsy/histo, PCR
In Geimsa or Gram stain ____ stained bacilli are seen
Negative stained organisms
M. lepraemurium: Treatment
surgical excision (difficult), Rifampin, Clarithromycin, Clofasimine- long term (intracellular)
In dogs, ____ is effective drug
Doxcycline
M. avium subsp. paratuberculosis
Johne’s disease in ruminants
Johne’s bacterium is found in
soil and water (even treated)
Johne’s primary host
Cattle
also infects sheep, goats, llamas, alpacas, deer
Johne’s disease: pathogenesis
chronic, progressive granulomatous enteritis
Johne’s effect spread is known as ___
Iceberg effect
1 animal maybe clinically affected with several more subclinically affected
Johne’s disease: clinical signs
Diarrhea, weight loss, bottle jaw, thickened ileal mucosa, enteritis
Johne’s: Gold standard test
Direct fecal culture on Herrold’s egg yolk medium
difficult, long (16 weeks)
Johne’s: diagnosis
PCR, ELISA, biopsy of tissue, Johnin skin test
Johne’s: contol
removing infected, management to reduce infection
antimicrobial treatment not recommended
Johne’s disease incubation period can last up to __
2 years
young animals are the most susceptible
Johne’s ELISA can result in false negatives in advanced stages due to __
Anergy