Mycobacterium Flashcards
Generally, what infections do mycobacterium cause?
pulmonary and extrapulmonary infections
Mycobacteria are acid-fast. Why?
because of their high lipid content in their cell walls
How do mycobacteria show up on gram stain?
they are gram negative rods
What type of organisms are Mycobacteria in regards to oxygen?
they are aerobic but they grow better in CO2
What type of media is typically used to grow Mycobacteria?
media that is egg-based
What disinfectants are mycobacteria resistant to?
halogen and quaternary ammonium disinfectants
What can kill mycobacteria?
phenol and substituted cresylic compounds
Are infections caused by Mycobacteria acute or chronic?
chronic
What type of parasites are Mycobacteria?
facultative intracellular parasites
What type of mycobacteria are killed by phagocytic cells and what type kill phagocytic cells?
saprophytic; pathogenic
Where in the cell are mycobacteria found?
in the cytoplasm of the macrophage
When mycobacteria rypture macrophages and adjoining cells are infected, what is formed as a result?
tubercles
Where are lesions from mycobacteria typically localized?
in the lungs, spleen, or liver
What are some immune mechanisms and proposed mechanisms by which mycobacteria are able to resist or alter the immune response?
- promote phagosome-lysosome fusion 2. Aggregate macrophages into epithelioid granulomas to restrict and contain mycobacteria 3. processing and presentation of bacterial antigens 4. Activation of T cells to control infection 5. increase microbicidal capacity of the granuloma by recruiting effector T cells to it
Why is the high lipid content of Mycobacteria important in their resistance to killing?
because they produce a variety of phospholipids, glycolipids, and sulfur-containing glycolypids that may interfere with host immune mechanisms
What is the immune response to Mycobacterium?
it is largely cellular and almost entirely mediated by macrophages. Leukocytes have been known to release reactive nitrogen and oxygen intermediates
What is Freund’s complete adjuvant?
a type of mineral oil that contains killed Mycobacterium smegmatis or M. phlei, but it is not used commercially due to lesions associated with the injection site
How is mycobacteria diagnosed?
since mycobacteria induces a delayed-type hypersensitivity reaction, the DTH reaction (intradermal skin test) is used to expose tubercle bacilli associated with mycobacteria
What antigen is used in the DTH reaction?
tuberculin
What are the different types of tuberculins used in the DTH test?
PPD (purified protein derivative) and OT (old tuberculins)
How are PPDs prepared?
by growing the organism on synthetic culture media, autoclaving, removing the cells, and precipitating the proteins with either ammonium sulfate or TCA
How are OTs prepared?
by growing bacilli on synthetic culture media
What type of tuberculins is used the majority of the time?
PPDs
What do drugs used to treat mycobacteria usually contain?
isoniazid and rifampin
What species does Mycobacterium tuberculosis infect?
primates
What specific disease does Mycobacterium tuberculosis cause?
tuberculosis
What famous scientist is associated with Mycobacterium tuberculosis?
Robert Koch
What other species does Mycobacterium tuberculosis infect?
zoo animals
In humans, tuberculosis is most often _______ in nature.
pulmonary
What lesions are associated with tuberculosis in humans?
lung lesions or cavitations that can develop and progress to the point that large blood vessels are compromised and the patient can bleed to death quickly; lesions occur in the vertebral column, kidneys, bladder, larynx, and other sites
How is tuberculosis treated?
six months of anti-TB drugs (1/3 kilogram a day)
What is the resistant strain of tuberculosis called?
XDR-TB
What is the recommended treatment for extensive drug resistant tuberculosis (XDR-TB)?
removal of lungs
What is the name of the most widely used human immunizing agent for TB in the world?
Bacille Calmette Guerin (BCG)
What does BCG contain?
a weakened live strain of Mycobacterium bovis
Who is BCG effective for?
infants and children
How do immunized individuals respond to PPD tubergulins?
positive - so it is hard to determine if they are immunized
What disease does Mycobacterium bovis cause and in what species?
tuberculosis in cattle, pigs, cats, horses, primates, dogs, sheep, and goats
What chemical in media inhibits the growth of Mycobacterium bovis?
glycerol
How long does it take for Mycobacterium bovis to grow on media?
3-4 weeks
What do cultures of Mycobacterium bovis look like?
rough and waxy
How is Mycobacterium bovis destroyed?
via pasteurization or direct sunlight
What species are making it difficult for Mycobacterium bovis eradication in the US?
white-tailed deer and farmed elk
How is Mycobacterium bovis transmitted?
primarily through a respiratory route and a small percentage of infections occur through the ingestion of milk, congenitally, and possibly venereally
What is the pathogenesis of Mycobacterium bovis?
once the individual is infected, the organism is ingested by macrophages, grows in the macrophage, kills and lyses it, then tuburcles made up of organism, macrophages, giant cells, and other inflammatory cells are encapsulated. The organism then travels through the lymph creating secondary metastasis
What is the immune response to Mycobacterium bovis?
primarily cell mediated immune responses that are effective about 4 weeks following the infection
How is Mycobacterium bovis diagnosed?
with the delayed type hypersensitivity (skin test) with PPD tuberculin (caudal fold test)
Explain the testing process within a herd of a suspect bovine tuberculosis patient.
A normal vet will do a caudal fold test, then they will report it to the state, then the state will do a comparative cervical test on that individual and if it comes back positive they will do a single cervical test on the entire herd
How are exotic ruminants diagnosed for Mycobacterium bovis?
Cervid TB Stat-Pak test which is a serologic test - only need to handle animals once
What is MAC?
Mycobacterium avium complex
What disease does Mycobacterium avium cause and in what species?
tuberculosis in avian species and swine
Which Mycobacterium avium species are more virulent for birds but can produce disease in swine and other animals?
Serotypes 1, 2, and 3
How are serotypes 1, 2, and 3 of Mycobacterium avium transmitted?
by ingestion of contaminated feces or soil in which organisms survive for a long time
What lesions are associated with serotypes 1, 2, and 3 of Mycobacterium avium?
lesions in bones, joints, liver, spleen, and the intestinal tract
What do lesions in the intestinal tract due to serotupes 1, 2, and 3, of Mycobacterium avium look like?
nodules that open and discharge into the lumen of the intestine
What serotypes of Mycobacterium avium typically cause disease in swine?
serotypes 1, 2, 4, and 8
What lesions are associated with serotypes 1, 2, 4, and 8 of Mycobacterium avium in swine?
foci in the mandibular and mesenteric lymph nodes and occasionally in the intestinal tract; lesions can occur in the liver and elsewhere
How are serotypes 1, 2, 4, and 8 of Mycobacterium avium transmitted in swine?
via ingestion
What disease is Mycobacterium leprae associated with and in what species?
leprosy in humans and armadillos
How is Mycobacterium leprae transmitted?
via respiratory to respiratory
What disease is associated with Mycobacterium lepraemurium and in what species?
leprosy-like disease in cats and rats
What lesions does Mycobacterium marinum cause and in what species?
swimmin pool granuloma on the arms and legs of humans and granulomatous lesions in cold-blooded aniimals
How do humans become infected with Mycobacterium marinum?
the organism travels from a site of trauma on an extremity that has contact with water
What occurs to Mycobacterium marinum when grown in the presence of light?
it produces a yellow pigment
What lesions does Mycobacterium kansasii cause and in what species?
lymph node lesions in cattle, deer, and swine
Mycobacterium kansasii is the second leading cause of ____-_________ mycobacterial _______ and causes both ______ and occasionally ________________ lesions in humans.
non-tuberculosis; infections; pulmonary; extrapulmonary
Mycobacterium kansasii is a _____ grower and is ________.
slow; photochromogenic
What lesions are associated with Mycobacterium fortuitum and in what species?
it produces pulmonary disease in dogs and humans
As compared to other Mycobacterium species, Mycobacterium fortuitum is _____ growing?
fast
What species does Mycobacterium chelonae typically infect?
swine, cold-blooded animals, and humans
What type of lesions does Mycobacterium chelonae cause in swine and cold-blooded animals?
lymph node lesions
What type of lesions does Mycobacterium chelonae cause in humans?
skiin lesions associated with patients receiving porcine heart valve transplants
True or False: Mycobacterium chelonae is a fast growing bacteria.
TRUE
What is MAP?
Mycobacterium avium subspecies paratuberculosis
What does MAP cause?
Johne’s disease
What lesions does Johne’s disease cause?
chronic proliferative enteritis
What species does Johne’s disease affect?
cattle, sheep, goats, camels, llamas, and some wild ruminants
What is the morphology of MAP?
smaller than the tubercle bacilli; short rod
Where is MAP found in infected species?
in tissues and feces
How long does it take for MAP to grow?
4-16 weeks on solid media
What compound is required for primary isolation of MAP?
mycobactin - an iron chelating compound
Where is MAP found in the environment?
in soil
What can kill MAP?
moderate heat, 5% formalin or 5% phenol
How is MAP transmitted?
from feces of individuals in the later stage of the disease to calves by ingestion; in utero ingestion is also found
What is the pathogenesis of MAP?
once ingested, the organism penetrates into the epithelium of the ileum and colon and is phagocytosed by macrophages, the organism multiplies within the macrophages and stimulates a granulomatous response that spreads through the intestines and regional lymph nodes. The intestine becomes very thickened due to proliferation of epitheliod cdells
What are the symptoms of clinical disease in cattle affected with Johne’s disease?
intermittent diarrhea and emaciation
How is MAP diagnosed?
PCR, culture, serologic responses, acid fast stain, and delayed type hypersensitivity testing
When diagnosing MAP, what are PCRs done on (what organic material)?
feces
What is the additive used to detect MAP in DTH?
johnin which is produced from culture filtrates of MAP
Is there treatment for MAP?
No - it is not attempted
How is Johne’s disease controlled?
immunization only in populations that have confirmed cases
Where is the Johne’s vaccination injected?
into the brisket of young calves
