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BACTERIOLOGY > 9 – Actinomycetales > Flashcards

9 – Actinomycetales Flashcards

1
Q

Microbiological characteristics

A
  • Diverse genera
  • Biocontainment level 1-2
  • Gram-positives
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2
Q

Actinomyces genera microbiological characteristics

A
  • Microaerophilic or anaerobic
  • Non-spore forming
  • Filamentous rods
  • *long and irregular
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3
Q

Nocardia genera microbiological characteristics

A
  • Similar cell wall to mycobacterium
  • Acid fast: pink structures
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4
Q

Trueperella pyogenes microbiological characteristics

A
  • Pleomorphic gram-positive coccobacilli
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5
Q

Dermatophilus congolensis microbiological characteristics

A
  • One of only 2 species within this genre
  • ‘tram-track’ appearance on cytology
    o Gram positive zoospores in parallel lines 2 across
    o Free living individual coccoid elements also visible
  • Pleomorphic in pure culture
  • *can make a definitive diagnosis by looking at a slide
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6
Q

Streptomyces spp. microbiological characteristics

A
  • Biocontainment level 1
  • ‘soil’ organisms
  • Source of useful natural products
    o Abs
    o Parasiticides (ex. ivermectin)
    o Chemotherapeutic agents (bleomycin)
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7
Q

Actinomyces and Trueperella: natural host or habitat

A
  • Host associated
    o Mucous membranes
    o Nasal cavity
    o Pharynx
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8
Q

Dermatophilus congolensis natural host or habitat

A
  • Maintained by carrier animals
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9
Q

Nocardia and streptomyces natural host or habitat

A
  • Environmental
  • Streptomyces spp. generally considered NON-pathogenic
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10
Q

Taxonomy tree:

A
  • MORPHOLOGY
  • Filamentous or not
    o Yes: acid fast or not
     Not: granules. Or not
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11
Q

Trueperella pyogenes: virulence factors

A
  • Pyolysin: cytotoxin
  • Neuraminidases, collagen binding proteins and fimbriae: adhesion
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12
Q

Pyolysin: cytotoxin of trueperella pyogenes

A
  • Against neutrophils
  • In lab animals, show to be dermonecrotic
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13
Q

Dermatophilus congolensis virulence factors

A
  • Proteases: tissue breakdown
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14
Q

Nocardia virulence factors

A
  • Facultative intracellular parasites
  • Grow in polymorphonuclear neutrophils
  • Inhibit phagosome-lysosome fusion in macrophages
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15
Q

Actinomyces bovis (cows)

A
  • ‘lumpy jaw’ (primarily in cattle, but other ruminants as well)
  • Part of NORMAL oral microbiota
    o Invasion with tissue DAMAGE
  • Mandibular lesions most common
  • Becomes painful if involves teeth (refuse to eat)
  • Prevent by ensuring access to high quality feed
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16
Q

Mandibular lesions with A. bovis

A
  • Periosteal new bone formation in response to infection
  • Fibrosis
  • Hard, immovable, painless mass
  • May develop draining tracts
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17
Q

Treat A. bovis

A
  • Debridement and antimicrobials
    o If draining tract: talk to surgeon, but manage with disinfectants
    o Penicillin
  • *can arrest lesion growth, but regression usually minimal
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18
Q

Actinomyces spp. (dogs and cats)

A
  • Normal microbiota
    o Pathology when enter normally sterile site (bites, inhaled/penetrating grass awns, foreign bodies)
  • Most commonly seen in mid-large breed dogs (hunting and sporting)
  • Often presents as a pyothorax
  • Variable presentation
  • Fluid within abscess
  • Often polymicrobial infections
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19
Q

Actinomyces spp (dogs and cats) other sites it can be

A
  • Pulmonary if aspiration of grass
  • Abdominal if foreign body migrates into abdomen (ex. from GIT)
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20
Q

Actinomyces spp (dogs and cats) presentation is variable

A
  • Head and cervical region most commonly affected
  • Firm of fluctuant lesions
  • Draining tracts
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21
Q

Actinomyces spp (dogs and cats) fluid with abscesses are often

A
  • Seroanguinous (containing blood and serous fluid) to purulent
  • Contain sulfur granules
  • Presence of filamentous rods
22
Q

Actinomyces spp (dogs and cats) treatment

A
  • Remove (find!) foreign body
  • Long term antimicrobials (penicillin)
23
Q

Actinomyces suis (pigs)

A
  • Commensal of the urogenital tract, cause of UTI
  • Clinical signs vary
  • Progression to pyelonephritis
24
Q

Actinomyces suis (pigs) clinical signs

A
  • Typically afebrile
  • Hematuria and pyuria (urine analysis)
  • May be found dead=acute renal failure
25
Q

Actinomyces suis (pigs) progression to pyelonephritis

A
  • Ascending infection to the kidney
  • Important reason for kidney to be rejected at slaughter
26
Q

Actinomyces suis (pigs) treatment

A
  • Antimicrobials: penicillin
  • Management
    o High hygiene
    o Ensuring sufficient access to water
27
Q

When hear actinobaculum sp. think

A
  • Urinary tract!
  • Also in people
28
Q

See D. congolensis infections when

A
  • Carrier animal present
  • Abundance of moisture (seasonal: fall, winter: in places warmer than SK)
  • Skin damage
29
Q

D. congolensis (horse, cattle, sheep)

A
  • Many species
  • Organisms live on skin, moisture stimulates release of zoospores=can be mechanically transmitted between animals
30
Q

D. congolensis (horses) lesions

A
  • Crusting lesions seen with dermatophilosis
  • Rain scald: back
  • Dew poisoning: lower extremities when horses kept on wet pastures
31
Q

D. congolenesis (sheep) lesions

A
  • Crusting lesions seen with dermatophilosis
  • Lumpy wool or ‘mycotic dermatitis’: skin
  • ‘strawberry footrot’: distal extremities
32
Q

D. congolenesis treatment (sheep)

A
  • topical disinfectants
  • antimicrobials (depending on animal species)
  • *wear gloves
33
Q

D. congolenesis management

A
  • remove from wet environment
  • discard crusts=source of infection for other animals
34
Q

D. congolensis associated lesions (various species)

A
  • suppurative and hyperkeratotic epidermiditis
  • hyperplastic skin with crusting lesions and coagulation necrosis
35
Q

D. congolensis (dogs and cats)

A
  • exudative skin disease
  • dogs: superficial on haired skin
  • cats: often abscessation
36
Q

D. congolensis (dogs and cats) treatment

A
  • keep skin dry and clean
  • bathing and crust removal
  • antibitoics (penicillins)
37
Q

Trueperella pyogenes clinical significance

A
  • wide variety of suppurative infections
  • opportunistic=no ‘classical presentation’
  • often component of polymicrobial infections
    o Fusobacterium necrophorum
  • spreading via septic emboli=common theme
38
Q

Trueperlla pyogenes ‘no classical presentation’

A
  • laryngeal abscesses in claves
  • liver abscesses in cattle
  • component of BRD (shipping fever)
  • arthritis, osteomyelitis, subcutaneous abscesses in pigs
39
Q

Trueperella pyogenes (cattle): liver abscess exemplifies role of septic emboli in pathogenesis (steps)

A
  1. Cattle fed highly fermentable diet
  2. Rumenitis results in lactic acidosis
  3. Translocation of rumen microbes into portal venous system
    a. Can get abscessation of caudal vena cava
  4. Septic emboli spread through venous system to R side of heart and into lungs
  5. Bacteria get stuck in capillary beds and set up secondary sites of infection
40
Q

Actinomycetales are fascinating group of bugs

A
  • Seen Arthrobacter sp grown from air in Mir space station
  • Brevibacterium: ‘cheese’ odour
41
Q

Species to collect for culture and microscopy

A
  • Exudates, aspirates
  • Fluid aspirated by thoracocentesis: companion animals (pyothorax)
  • Crusts: D. congolensis
  • Mastic milk
42
Q

Histopathology samples

A
  • Granuloma biopsies
43
Q

Sample handling

A
  • For histology fix in 10% formalin
  • Do NOT freeze samples for culture
44
Q

Lab ID: smears of aspirates

A
  • EXTREMELY ASPIRATES
  • Filamentous rods
    o Gram positive
    o Acid fast
  • Granules in pus (actinomyces spp.)
  • Tram tracks (D. congolensis)
  • *beware: Nocardia can be missed on H&E stained slides
45
Q

Lab ID: culture

A
  • Actinomyces grow well on blood agar
    o CO2 incubator (tell the lab if ‘lumpy jaw’)
  • Species level ID can be challenging
  • MALDI useful (may not rely on species ID)
  • *new technology to differentiate previously lumped together species
46
Q

Actinomyces spp. zoonotic/interspecies transmission

A
  • Commonly part of oral microbiota
  • Disease not classically transmitted from animals
47
Q

Trueperella pyogenes zoonotic/interspecies transmission

A
  • Human infections rare, not major concern
48
Q

Dermatophilus congolensis zoonotic/interspecies transmission

A
  • Skin infections possible in people in contact with infected animals and have skin trauma (insect bites)
  • *wear gloves
49
Q

Treatment options: actnomyces spp.

A
  • Penicillins
50
Q

Treatment options: nocardia spp

A
  • Sulfonamides or sulfa/trimethoprim
51
Q

Treatment options: trueperalla pyogenes

A
  • Pencillins
  • tetracyclines
52
Q

Drugs to avoid?

A
  • Most actinomyces spp. are METRONIDAZOLE RESISTANT

BACTERIOLOGY (19 decks)

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