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Bacteriology > Corynebacterium rhodococcus > Flashcards

Corynebacterium rhodococcus Flashcards

1
Q

Characteristics

A

-biocontainment level 2
-aerobic and facultative anaerobes

-Corynebacterium= gram positive clubbed rods (chinese letter, palisades), colony morphology is variable

-Rhodococcus= gram positive cocco-bacilli
*R. equi=pink colonies

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2
Q

Habitat

A

-part of normal microbiota of skin, mucous membranes, intestinal tract

-can survive in environment
>ex. Corynebacterium pseudotuberculosis= 55 days in environ
>ex. Rhodococcus equi= soil organism; feces contaminated soil

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3
Q

Differentiation of corynebacterium vs rhodococcus

A

Corynebacterium: fermentative. Differ further by CAMP test and colony colour

Rhodococcus: unreactive

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4
Q

Virulence factors of C. renale, cystitidis, pilosum

A

-pilli for attachment

-urease= production of ammonia (uropathogens)

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5
Q

Virulence factors of C. pseudotuberculosis

A

-Phospholipase D- essential; deficient strains experimentally shown to be incapable of causing classical lesions in lymph nodes
>damages host cell membranes, facilitates spread
>cytotoxic= erythrocytes and enutrophils

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6
Q

Virulence factors for R. equi

A

Vaps (virulence associated proteins)
-Vap A allows organisms to survive intracellularly, prevents acidification of phagsome

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7
Q

Virulence factors of C. diphtheriae

A

diptheria toxin acts by interfering with host cell protein synthesis

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8
Q

C. pseudotuberculos in sheep and goats, camels

A

-causes caseous lymphadenitis
-characterized by pyogranulomatous abscesses of lymph nodes and organs (inspissated material/cheese like)
- highly contagious; difficult to eradicate when present
**Treatment: antimicrobials don’t penetrate lesions

-worldwide, common in California

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9
Q

C renale group in cattle

A

-includes C. renale, cystitidis, pilosum
-cause infections of bovine urinary tract:
1.Cystitis- infection of bladder- see hematuria and proteinuria
2. Pyelonephritis- infection of kidney- see fever, depression, reduced feed intake

-maintained in herd by subclinical carriers and diseased animals. Transmission by urine droplets splashing onto vulva

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10
Q

Attachment facilitation of C. renale group

A

-Facilitated by alkaline conditions; inhibited by acid
>urease producing organism= converts urea to ammonia
>urinary acidification

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11
Q

Treatment for C. renale group

A

-penicillin

**treatment success decreases as disease progresses
>difficult to eradicate from kidney and prognosis worsens with increasing renal damage
>high cull rate

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12
Q

Balanoposthitis

A

-caused by C. renale in sheep
-inflammation of penis and prepuce
-predisposed by high protein diets resulting in high urea concentration

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13
Q

Steps of balanoposthitis

A

1.Urea converted into ammonia by organism
2. Ammonia irritates penis
3. Inflammation and ulceration
4.Bacteria enter compromised tissues
5. Scarring over prepuce prevents extrusion and breeding

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14
Q

Treatment of balanoposthitis

A

combination of antimicrobials (penicillin) and debriding dead tissue and removing excess wool

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15
Q

Skin infections in dogs and cats

A

C. auriscanis and C. ulcerans
*often polymicrobial infections

-treament challenging

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16
Q

C. urealyticum in dogs and cats

A

-rarely causes UTIs

17
Q

C. diphtheriae

A

-mostly infects humans
-often respiratory diphtheria (pseudo-membrane forms over pharynx)
-disease caused by toxigenic strains

**vaccine available (diphtheria, pertussis, tetanus)

18
Q

R. equi in horses

A

-infected when they inhale virulent VapA +isolates
-causes severe, chronic, suppurative bronchopneumonia in young foals (3wks to 5mths) OR abscesses in older horses

19
Q

R. equi as an enteric disease

A

-seen in 50% of foals with pneumonia
>fecal-oral or swallowing expectorated sputum, usually pneumonia first
>multi-focal ulcerative enterocolitis and typhlitis
>see weight loss, diarrhea, colic

20
Q

Prognosis of R. equi in horses

A

-Fair in foals with chronic disease
-poor in foals with acute disease

21
Q

Treatment of R. equi

A

-antimicrobials
*Rifampin and macrolide type drug

22
Q

Management for R. equi

A

-little evidence for preventative measured but it is from environment so cleaning, avoid crowding, reduce dust, well ventilated areas

23
Q

R. equi in cats

A

-rarely reported but increasing in cats and immunocompromised individuals
-cause cutaneous lesions (pyogranulomatous inflammation; typically not painful or febrile)
-also may see draining tracts and lesions of parenchymal organs

24
Q

R equi treatment in cats

A

-surgical drainage and antimicrobials

25
Q

Specimens to collect

A

-pus or exudates- C. pseudotuberculosis
-mid-stream urine- C. renale group
-Trans-tracheal wash- R. equi

26
Q

Sample handling

A

-swabs should be sent with transport media
-do not freeze samples

27
Q

Lab ID of corynebacterium

A

-growth on blood agar
-cytology important

28
Q

Rhodococcus lab ID

A

-standard culture. But may grow better at low temps (30degrees), make sure to inform lab if this is suspected

-partially acid fast, may see them associated with macrophages on cytology

-growth may take up to 48hrs
-readily ID biochemically

29
Q

C. pseudotuberculosis lab ID

A

-immunological tests are available to detect exposure/infection in cases where abscesses are not superficial enough to sample

30
Q

Susceptibility testing

A

-no recognized guidelines for this type of bacteria
>interpret lab results with caution and consult the lab

31
Q

Zoonotic transmission bacteria

A
  1. c. pseudotuberculosis
  2. C. renale group
  3. Toxogenic C. ulcerans
  4. R. equi
32
Q

C. pseudotuberculosis in humans as zoonosis

A

-abscesses in humans associated with sheep herders
-risk during sheering or while performing necropsy

33
Q

C renale group as zoonosis

A

-low risk to human health

34
Q

C. ulcerans in people as zoonosis

A

-causes cutaneous diphtheria in people
-isolated from animals

35
Q

R. equi as a zoonosis

A

-primarily an issue in immunocompromised patients (lymphoma, Hodgkin’s disease, AIDS, transplantation patients)

36
Q

Treatment options for C. pseudotuberculosis

A
  1. Intracellular infections- antimicrobial therapy difficult because adequate drug concentration not well known
  2. Control measures depend on prevalence of disease
    -Eliminate infections (low prevalence regions)
    -minimize disease impact (high prevalence regions)
37
Q

Treatment for Corynebacterium spp

A

-intrinsically resistant to fosfomycin

** may be relevant if treating UTI in a companion animal

38
Q

Treatment for Rhodococcus

A

-Think MLSbK + rifampin

-Intrinsic resistant to penicillin, ampicillin, cephalosporin

Bacteriology (16 decks)

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