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RUSVM Bacteriology Gram Positives > Mycobacterium > Flashcards

Flashcards in Mycobacterium Deck (52)
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1

Mycobacterium description

**Aerobic & Acid fast!** non spore-forming rods, No flagella or capsules, Gram positive but poor at staining

2

What does it mean to be acid fast?

Can bind phenol based dyes and resist discoloration

3

Mycobacterium Major diseases

*Tuberculosis* - Paratuberculosis - Granulomatous diseases

4

Mycobacterium Virulence factors

Lipids/glycolipids/peptidoglycolipids - Alkyl hydroperoxidase reductase - Sufolipids, phosphatidyl inosital mannoside, surface mycosides, waxes - Glycolipid Dimycolyl trehalose - Mycobactins & exochelins

5

Mycobacterium virulence factors that aid in intramacrophage survival & account for acid-fastness

Lipids, glycolipids, peptidoglycolipids

6

Mycobacterium virulence factors that are responsible for resistance

Alkyl hydroperoxidase reductase

7

Mycobacterium virulence factor - "cord factor"

Dimycolyl trehalose glycolipid

8

Mycobacterium virulence factor for iron acquisition

Mycobactins & Exochelins

9

Tuberculosis - 3 species responsible

*Reportable Disease*!!!! - M. tuberculosis, M. bovis, M. avium

10

Tuberculosis - Reservoir species of different Mycobacterium species

Humans (M. tuberculosis) - Cattle & wild mammals (M. bovis) - Birds (M. avium)

11

Tuberculosis- Transmission

Mainly inhalation & ingestion - Transplacental, transovarian - intrauterine also possible

12

Tuberculosis Pathogenesis

- Inhalation--> respiratory tract, adjacent lymph nodes & serous cavities - Hematogenous dissemination to liver & kidney - Rare udder infection (zoonotic!!) - Some transplacental to calves (liver & spleen lesions if not aborted)

13

Tuberculosis Disease patterns

Acute exudative process - Neutrophilic - Large infecting dose favored (inhalation) - High virulence - Predisposition of host - Loose tissue architecture (lungs) - Emaciation - Low grade fever - Enlarged lymph nodes - cough - diarrhea (tissue damage from cytokines, help spread organism)

14

What Tuberculosis signs arise after effective cell-mediated immune response?

Localized arrested pulmonary lesions

15

What Tuberculosis signs arise after ineffective cell-mediated immunie response?

Active pulmonary tuberculosis, generalized tuberculosis

16

Tuberculosis in ruminants - causative species

M. bovis!! sometimes avium/tuberculosis

17

Tuberculosis in ruminants- Disease pattern

Granulomatous lesions all over lungs, serous cavity surfaces! -

18

Tuberculosis in horses

M. avium - Rare - GI infection, pharynx & intestine, maybe lungs, spleen & serous membranes

19

Tuberculosis in pigs

M. bovis & avium - GI, Miliary lesions in liver & spleen

20

Tuberculosis species in Dogs & Cats

Mainly M. bovis

21

When I say Marie's Disease, you say...

Dog tuberculosis - M. bovis

22

Tuberculosis in dogs

Marie's Disease - Hypertrophic pulmonary osteoarthropathy

23

Tuberculosis in cats

Intestinal & abdominal localization, ulcerative skin lesions

24

Tuberculosis in birds

M. avium complex - Grows @ higher temp - Alimentary infection--> disseminate to liver & spleen. Transovarian infection to chicks rare

25

Tuberculosis in foals! and DDx for gram positive, aerobic bacteria causing pneumonia

Rare! DDx : Rhodococcus equi

26

Tuberculosis species in primates

M. bovis (mainly) M. tuberculosis, M avium & non-tuberculous mycobacteria in immunosuppressed

27

M. tuberculosis in primates

Airborne route, mostly respiratory tract infections

28

M. bovis in primates

Ingestion, unpasteurized milk!!

29

Case Study - Nasty picture of gross growth on vet surgeons finger

Verrucose lesion of cutaneous tuberculosis

30

Tuberculosis breed resistance

Zebu cattle (with hump) more resistant than other breeds.

31

Tuberculosis vaccine>

Available - Temporary immunity & hypersensitivity in humans - Interferes with interpretation of testing so ONLY for eradicated places

32

Mycobacterium avium subspecies

4 subspecies (avium, paratuberculosis, silvaticum, hominissuis)

33

When I say Johne's disease, you say...

Mycobacterium avium paratuberculosis!

34

When I say transverse corrugation of intestinal mucosa of ruminants, you say...

Johne's Disease! Mycobacterium avium paratuberculosis!

35

M. avium paratuberculosis

Johne's Disease! Chronic, irreversible wasting disease. **REPORTABLE**

36

M. avium paratuberculosis - species affected

Symptomatic/asymptomatic in wild & domestic ruminants, swine & rabbits

37

M. avium paratuberculosis transmission

Ingestion - contact with fecally-contaminated materials (in utero or colostrum ingestion also possible

38

Johne's Disease pathogenesis

Cell mediated immune phenomena (12 mo incubation pd) --> survive & replicate inside M cells** --> macrophages release cytokines--> TH1 recruited (tuberculoid stage) --> IFN-g compromised, fails to eliminate bacteria --> Progressive granulomatous reaction (TH2 recruitment) --> sloughing of mucosal epithelium=lepromatous stage

39

Johne's Disease pathogenesis Lepromatous stage

TH2 recruitement - Sloughing of mucosal epithelium

40

Johne's Disease pathogenesis Tuberculoid stage

TH1 recruitment

41

Johne's Disease in ruminants

Chronic weight loss, diarrhea, permanent transverse corrugation of intestinal mucosa - Enlarged draining lymph nodes w/ macrophages w/bacteria

42

Johne's Disease - breeds especially susceptible

Guernsey, Shorthorn, Jersey

43

Johne's Disease When disease most occurs

In young - Domestication/captivity - Stress, crowding, shipment etc

44

Johne's Disease Dx

Intradermal test - can be messed up with vaccination

45

Feline leprosy - causative agent & description

M. lepraemurium - chronic noduloulcerative nonTB mycobacterial infection of skin - Transmission by rodent bite - Poor prognosis

46

M. lepraemurium description

Acid fast agent, very fastidious (picky about growth medium)

47

Canine Leproid Granuloma Syndrome

Uncultured, saprophytic mycobacterium - Numerous acid-fast organisms - Condition of subcutis & skin of pinnae, face, body extremities

48

Ulcerative dermatitis of cats & dogs - Causative agents

M. fortuitum, M. chelonae, & others

49

Ulcerative dermatitis of cats & dogs - Description

Chronic, non-healing skin lesions, months to years - Pyogranulomatous inflammation - poor-staining organisms

50

Bovine Farcy

Bovine Mycobacterial Ulcerative Lymphangitis - Nodular-ulcerative skin lesions of lower extremitis & ventral trunk - May cause false positive tuberculin reactivity

51

Bovine Farcy causative agents

M. farcinogenes, M. senegalenses (and Nocardia farcinca)

52

Mycobacterium in aquatics

Zoonotic significance - "swimming pool granuloma" or "fish handler's disease"