Mycobacterium spp. Flashcards
Is corynebacterium gram positive or gram negative?
Gram Positive w/ Mycolic Acid
Oxygen requirement?
Aerobic growth
T/F: Mycobacterium survives well in the environment
True
M. Avium is found in patients that are ____________
Immunocompromised and intracellular lay
Mycobacterium avium subsp. paratuberculosis is the scientific name of _______
Johne’s Disease
What type of pathogens are Mycobacterium?
Facultative intracellular pathogens (survive in macrophages)
What type of immunity is assoc. with Mycobacterium?
Cellular - Th1 response
What type of inflammation is assoc. with Mycobacterium?
Granulomatous inflammation (CHRONIC)
What are the 2 virulence factors associated with Mycobacterium?
- Mycolic acid containing cell wall lipids
2. Cell protein antigens
Mycolic acid in the cell wall allows for ________(3)
Survival in macrophages, stimulate cytokines production, enhance immunomodulating effects
What protein is involved with Cell Protein Antigens (virulence factor)
Tuberculin
Mycobacterium spp. stains Acid fast __________ bacteria, and the reaction is generally ___________
Positive, and weak
M. tuberculosis, M. avium subsp. paratuberculosis, M. leprae, and M. lepraemurium are all considered ________________ pathogens
Obligate Pathogens
Most spp. of Mycobacterium are soil and water ___________
Saprophytes - they can opportunistically infect hosts
Important Diseases caused by Mycobacterium (5)
M. tuberculosis / M. bovis - mammalian tuberculosis
M. Avium subsp. avium - avian tuberculosis
M. Leprae (human) - leprosy
M. Lepraemurium (cat) - leprosy
M. avium subsp. paratuberculosis - Johne’s disease
M. tuberculosis (human) is transmitted via
Inhalation
M. bovis is transmitted via:
Ingestion
What type of hypersensitivity is associated with Tuberculosis?
Type IV (Delayed) Hypersensitivity
What type of necrosis is assoc. with Tuberculosis (think M. avian subsp. paratuberculosis)
Caseous necrosis
What kind of lesions are assoc. with Tuberculosis?
Granulomas
What types of tubercles can form from Granulomas? (2)
- “Hard” Tubercle - epithelioid macrophages
2. “Soft” Tubercle - caseous necrosis
What type of epithelioid cells surround the Granuloma (tubercle)
Multinucleated giant cells (Langhan’s cells)
What are the elements of a Granuloma (tubercle)?
- Activated macrophage/epithelioid cells
- Lymphocytes
- Fibrosis
- Mineralization
- Coagulative/ caseous/ liquefactive necrosis (sometimes seen)
Who are the reservoirs for M. tuberculosis?
HUMANS
Is M. tuberculosis zoonotic?
YES
What is the transmitting route from Elephants-humans?
Through aerosol
What are the 4 PRIMARY drugs to treat TB?
Isoniazid
Rifamycins
Ethambutol
Pyrazinamide
What are the two secondary drug types to treat TB?
Aminoglycosides
Fluoroquinolones
Can you use combination drug therapy with TB?
Yes, combination therapy is needed
What drugs are associated with Multi-drug resistance TB (MDR-TB)?
Isoniazid and Rifampin
Is M. Bovis zoonotic?
YES - zoonotic TB
What is the main portal of entry for M. bovis?
The GI Tract
What is the host range for M. bovis?
BROAD RANGE - primarily bovine but can infect opossum, badgers, deer, and several other wildlife spp.
At what stage is M. bovis (Bovine TB) recognized?
Very advanced stages (earlier stages are generally unrecognizable); sometimes unrecognized until slaughter
What is the most common mode of transmission for M. bovis?
Aerosol*** among cattle
How do most humans acquire M. bovis?
In unpasteurized / contaminated milk
Where does M. bovis enters the body for cattle? For badgers?
Cattle - at any site
badgers - through skin wounds
What are the typical clinical signs assoc. with M. bovis?
Enlarged regional lymph nodes and generalized wasting
How would you diagnose Bovine TB?
Tuberculin test Acid-fast stain Culture PCR *Tuberculin hypersensitivity skin tests*
What vaccines are available (if any) for cattle and humans for M. bovis TB?
Cattle - no vaccines available
Humans - vaccine for high prevalent areas
What are the primary hosts for Johne’s Disease?
Ruminants (CATTLE)
What condition is associated with Johne’s Disease?
Chronic, progressive granulomatous enteritis
Pathogenesis of M. avium subsp. paratuberculosis?
Granulomatous enteritis
How do cattle develop M. avium subsp. paratuberculosis?
Infection via ingestion of contaminated milk OR in utero
What disease is associated with having an “iceberg effect?
M. avium subsp. paratuberculosis ** - numerous asymptomatic shedders (in feces, and sometimes milk)
Infected herd: 35% immune, 60% asympt. shedders, 2-5% develop clinical disease
What are the symptoms associated with M. avium subsp. paratuberculosis? (2)
Diarrhea and weight loss (due to disruption of ileo-cecal mucosa)
How would you diagnosis Johne’s Disease?
SEROLOGY (ELISA - milk, serum)
What mechanism can result in advanced stages of Johne’s Disease is left untreated?
A nervy
What age group is most susceptible to infection of Johne’s Disease?
Young - incubation period can be up to 2 yrs.
How to treat Johne’s Disease?
Culling sick Detection/isolation Separate calves at birth Pasture rotation Possible vaccination (usually restricted)
M. Paratuberculosis may have a role in which disease?
Crohn’s Disease
Mycobacterium avium complex (MAC) has 3 subsp. that are…?
Subsp. avium - Avian TB
Subsp. sylvaticum - Non-TB (atypical) mycobacteriosis
Subsp. hominisuis - pig and human
What type of infections does MAC cause?
Opportunistic granulomatous infections in humans, animals, and birds
Where is MAC typically found?
In soil and water (low pH, high temp tolerance)
M. Ulcerans and Burundi ulcer is a frequent Mycobacterium disease in what host?
Humans - devastating disease
In what region (topics / cold) would you find M. ulcerans?
Tropical wetlands
M. Leprae is otherwise known as (common name)?
Leprosy or Hansen’s Disease
Transmission of M. leprae is from shedding through _______
Nose
What is the only known reservoir?
Nine-banded Armadillo
Few acid fast positive bacilli in a lesion is associated with which type of leprosy?
Tuberculoid (paucibacillary)
No cell mediated response, severe disease, with numerous acid fast positive bacilli, is assoc. with what type of leprosy?
Lepromatous (multibacillary)
M. Lepraemurium is also called ____ (common name)?
Feline and Murine Leprosy
What are the lesions associated with M. lepraemurium?
Solitary/multiple cutaneous nodules OR ulcerated lesions
Pathogenesis assoc. with M. lepraemurium?
Granulomatous Dermatitis Panniculitis
Diagnosis via:
Geimsa Stain
PCR
Acid Fast Stain
What drugs are used for treatment?
Rifampin, Clarithromycin, Clofazimine
Doxycycline for dogs
Saprophytic Mycobacterium spp. Have what type of host response? (What host pathogenesis?)
Granulomatous to pyogranulonatous
chronic non-healing cutaneous lesions with lack of anti-microbial treatment
