BacT - Week 6, Lecture 1

Mycobacterium oxygen requirements:

aerobic

Do Mycobacterium make spores?

no

What shape is mycobacterium?

rod

Mycobacterium is Gram-___________

positive

What stain do you use for mycobacterium? What part of the bacteria is it actually staining?

acid-fast (ZN); lipid and mycolic acid in cell wall

What makes mycobacterium resistant to adverse environmental influences?

lipid-rich wall

Mycobacterium is susceptible to __________

pasteurization

Do pathogenic or non-pathogenic Mycobacterium grow slowly?

pathogenic

Mycobacterium grows on what media type?

egg-enriched

Diseases caused by Mycobacterium are (acute or chronic?) and _____________

chronic; progressive

Major diseases caused by Mycobacterium:

* TB
* Johne’s disease
* feline leprosy

What Mycobacterium are in the Mycobacterium tuberculosis complex?

* M. tuberculosis
* M. bovis

Mycobacterium tuberculosis is important in what spp?

humans

M. avium subsp. paratuberculosis is important in what spp?

ruminants

What are the growth rates for:

* M. tuberculosis
* M. bovis
* M. avium
* M. avium subsp paratuberculosis

* slow
* slow
* slow
* very slow (up to 16wk)

What are the optimal incubation temps for:

* M. tuberculosis
* M. bovis
* M. avium
* M. avium subsp paratuberculosis

* 37
* 37
* 37-43 Celcius
* 37

What bacterium has an essential growth supplement? What is it?

M. avium subsp paratuberculosis; mycobactin

What safety precaution do you need to use for Mycobacterium?

biohazard cabinet

Mycobacterium Dx features:

________(+/-) staining rods of Giemsa

________(color) on acid-fast staining (ZN)

negative; pink

Getting a (+) result on a ZN stain does not mean it 100% is Mycobacterium. Why?

other bacT have small amounts of mycolic acid (partial acid fast)

Pathogenic mycobacterium grow slow on solid media, __________ grow fast

saprophytes

Can you biochemically differentiate the spp of Mycobacterium?

no, need PCR

Why would you culture Mycobacterium?

confirm VIABLE bacteria in clinical samples

You can do a PCR for Mycobacterium from what 2 things?

culture and clinical samples

What bacT causes Mammalian tuberculosis?

M. tuberculosis complex

What bacT causes avian tuberculosis?

M. avium subsp avium serotypes 1-3

What bacT causes Johne’s disease?

M. avium subsp paratuberculosis

What bacT causes leprosy?

M. leprae (human), M. leptaemurium (cat)

How long can M. tuberculosis complex survive in the environment? What conditions does it like?

months; cold, dark, moist

What is the main reservoir for M. tuberculosis?

humans

Tuberculosis (Mt) in humans is an emerging ___________ and _____________

zoonosis; anthropozoonosis

_______________ transmission is very common for M. tuberculosis

elephant-to-human

There are some _________ infections of M. tuberulosis in some wildlife populations such as banded mongoose in Botswana and suricates in south africa

endemic

Tuberculosis (Mt and Mb) symptoms in humans:

* cervical _________
* tonsillar and pre-auricular _________ in children
* infected via skin → localized skin disease (______ and ________)
* ___________ disease can result in kidney failure

lymphadenopathy; LN; benign; self-limiting; genitourinary

Tuberculosis in humans is a __________ disease

notifiable

Can you distinguish M. tuberculosis from M. bovis?

no

What makes eradication of M. bovis so difficult?

reservoirs in wildlife

What are the 3 statuses of Bovine Tuberculosis (Mb):

* widespread TB
* TB eradication programs in progress
* TB free

What is the problem spp for Bovine TB in the UK and ireland?

badgers

What is the problem spp for Bovine TB in New Zealand?

opossum

What is the problem spp for Bovine TB in Michigan?

white-tailed deer

What are the ways a cow can get infected with Bovine TB from other cows?:

* aerosol (most)
* ingestion (calves)
* asymptomatic carriers

What method of transmission is most common for calves to get bovine TB from other cows?

ingestion

What are the ways that humans get bovine TB from cattle?:

* ingestion (unpasteurized dairy and undercooked meat)
* aerosol

What are the ways that cats get infected with Bovine TB?:

* ingestion
* aerosol
* bite/scratch

What are the ways that pigs, ferrets and deer get infected with Bovine TB?

ingestion

What are the ways that badgers get infected with Bovine TB?

bite/scratch

What are the virulence factors of Bovine TB:

lipid composition (survive in macrophages)

How does Bovine TB survive in macrophages?

cell wall (glycolipid) blocks phagosome-lysosome fusion

________________ is important in the destruction of Mb bacilli

cell mediated IR

If the Mb bacT survive the cell mediated IR, then _____________ inflammation and formation of a ______ will occur due to a type IV/delayed hypersensitivity

chronic granulomatous; tubercle

The chronic granulomatous inflammation and formation of a tubercle in Mb is due to what occuring?

type IV/delayed hypersensitivity

Macrophages infected with Mb secrete cytokines to recruit __________ which assist the granuloma formation and containment of the organisms

lymphocytes

After macrophages recruit lymphocytes, _________ secrete cytokines recruiting more macrophages

T cells

The typical host response to Mb is gradual accumulation of macrophages around the lesion with a ____________ core resulting in a tubercle or ganuloma

central, necrotic

The granuloma of Mb facilitates the interaction between _________ and ________ (cells) and containment or destruction of the pathogen

macrophages and T cells

Why does the host’s body create a layered structure around the Mb?

separate necrotic core from surrounding tissue

Granulomas from Mb may be histologically visible as early as ________(time) after experimental infection

3wks

How does Mb disseminate?:

* macrophages migrate with viable mycobacterium
* rupture of granuloma

What initiates and makes the capsule in a Mb infection?

fibroblasts

In a Mb infection, what cells do you expect to see?

* fibroblasts
* giant cells
* epithelioid cells (altered macrophages)

Tuberculous _________ facilitates infection to calves and cats

mastitis

In early stages, Mb lesions are…

difficult to detect

In older lesions of Mb, _____ has formed and ________ necrosis has occurred

capsule; central caseous

What do you use for a Mb skin test?

tuberculin (purified protein derivative; PPD)

Where do you do your first Tuberculin skin test? How long do you wait for a result? What will it look like if it is positive?

caudal fold; 72hr; thick and swollen

What do you do if your tuberculin skin test in the caudal fold comes back positive? What does it test for?

comparative cervical test; bovine and avian PPD

For the comparative cervical test, an increase in skin thickness at the injection site of bovine PPD which exceeds that at the avian PPD injection site by ______ (measurement) or more is interpreted as evidence of infection and the animal is termed a reactor

4mm

What test do you use for Mb in cervids?

single cervical test

What does a false positive Mb test mean? What do you do?

other mycobacterium; comparative cervical

What can a false negative Mb test be from?:

* before 30 days of infection
* anergy
* immunosuppression from stress

You can take samples of what to detect M. bovis:

* LN
* tissue lesions
* aspirates
* milk

What can you use to detect a Mb infection earlier than the tuberculin test?

gamma interferon

What can you do to detect a Mb infection in later stages of infection?

ELISA

What is the methods for controlling Mb?:

* test-and-slaughter
* specific sanitation

Is there a vx for Mb?

no

Avian TB is most common in what birds?

free-range adults

How does avian TB get into the soil?

bird poop

How is avian TB transmitted?

fecal-oral

How do you dx avian TB in live animals? What about histologically?

avian PPD injected into wattle; ZN stain

Does M. avium affect humans?

immunocompromised

How are pigs infected with M. avium complex? What CS will they get?

eating uncooked swill; small tubercles in LN

Johne’s disease is aka

Paratuberculosis (MAP)

Johne’s disease is caused by what bacterium?

M. avium subsp paratuberculosis

What types of cows are getting Johne’s disease?

dairy cattle

Johne’s disease has a possible etiology in _________ disease

Chron’s

Transmission of Johne’s disease:

* fecal-oral (high)
* colostrum (low)
* milk (low)

Feeding _________ is a risk factor for Johne’s disease

pooled colostrum

Resistance to infection from Johne’s disease will ________ with age

increase

Infection of Johne’s disease occurs earlier in life but CS rarely develop in cows less than ________ old

2yr

Sub-clinically infected carriers of Johne’s disease will _____________ in herd

maintain disease

For every 1 cow with Johne’s disease, how many are infected without CS?

7

After ingestion of MAP and uptake in _________ of SI, it infects macrophages in the GIT and associated _______

peyer’s patches; LN

Can Johne’s disease disseminate?

yes

Animals infected with Johne’s disease can appear _________

healthy

What are the main CS of Johne’s disease:

* D+
* coat color fades
* ventral/intermandibular edema

Macroscopic lesions of Johne’s disease:

thickened intestine and enlarged LN

What would you see histologically from Johne’s lesions:

* diffuse granulomatous enteritis
* epithelioid macrophages
* giant cells

What is the easiest way to detect MAP in a live animal?

feces

What are the ways to detect MAP post mortem:

* tissue from intestines and regional LN
* ZN stain
* culture
* PCR