9 – Actinomycetales Flashcards
Microbiological characteristics
- Diverse genera
- Biocontainment level 1-2
- Gram-positives
Actinomyces genera microbiological characteristics
- Microaerophilic or anaerobic
- Non-spore forming
- Filamentous rods
- *long and irregular
Nocardia genera microbiological characteristics
- Similar cell wall to mycobacterium
- Acid fast: pink structures
Trueperella pyogenes microbiological characteristics
- Pleomorphic gram-positive coccobacilli
Dermatophilus congolensis microbiological characteristics
- 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
Streptomyces spp. microbiological characteristics
- Biocontainment level 1
- ‘soil’ organisms
- Source of useful natural products
o Abs
o Parasiticides (ex. ivermectin)
o Chemotherapeutic agents (bleomycin)
Actinomyces and Trueperella: natural host or habitat
- Host associated
o Mucous membranes
o Nasal cavity
o Pharynx
Dermatophilus congolensis natural host or habitat
- Maintained by carrier animals
Nocardia and streptomyces natural host or habitat
- Environmental
- Streptomyces spp. generally considered NON-pathogenic
Taxonomy tree:
- MORPHOLOGY
- Filamentous or not
o Yes: acid fast or not
Not: granules. Or not
Trueperella pyogenes: virulence factors
- Pyolysin: cytotoxin
- Neuraminidases, collagen binding proteins and fimbriae: adhesion
Pyolysin: cytotoxin of trueperella pyogenes
- Against neutrophils
- In lab animals, show to be dermonecrotic
Dermatophilus congolensis virulence factors
- Proteases: tissue breakdown
Nocardia virulence factors
- Facultative intracellular parasites
- Grow in polymorphonuclear neutrophils
- Inhibit phagosome-lysosome fusion in macrophages
Actinomyces bovis (cows)
- ‘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
Mandibular lesions with A. bovis
- Periosteal new bone formation in response to infection
- Fibrosis
- Hard, immovable, painless mass
- May develop draining tracts
Treat A. bovis
- Debridement and antimicrobials
o If draining tract: talk to surgeon, but manage with disinfectants
o Penicillin - *can arrest lesion growth, but regression usually minimal
Actinomyces spp. (dogs and cats)
- 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
Actinomyces spp (dogs and cats) other sites it can be
- Pulmonary if aspiration of grass
- Abdominal if foreign body migrates into abdomen (ex. from GIT)
Actinomyces spp (dogs and cats) presentation is variable
- Head and cervical region most commonly affected
- Firm of fluctuant lesions
- Draining tracts
Actinomyces spp (dogs and cats) fluid with abscesses are often
- Seroanguinous (containing blood and serous fluid) to purulent
- Contain sulfur granules
- Presence of filamentous rods
Actinomyces spp (dogs and cats) treatment
- Remove (find!) foreign body
- Long term antimicrobials (penicillin)
Actinomyces suis (pigs)
- Commensal of the urogenital tract, cause of UTI
- Clinical signs vary
- Progression to pyelonephritis
Actinomyces suis (pigs) clinical signs
- Typically afebrile
- Hematuria and pyuria (urine analysis)
- May be found dead=acute renal failure
Actinomyces suis (pigs) progression to pyelonephritis
- Ascending infection to the kidney
- Important reason for kidney to be rejected at slaughter
Actinomyces suis (pigs) treatment
- Antimicrobials: penicillin
- Management
o High hygiene
o Ensuring sufficient access to water
When hear actinobaculum sp. think
- Urinary tract!
- Also in people
See D. congolensis infections when
- Carrier animal present
- Abundance of moisture (seasonal: fall, winter: in places warmer than SK)
- Skin damage
D. congolensis (horse, cattle, sheep)
- Many species
- Organisms live on skin, moisture stimulates release of zoospores=can be mechanically transmitted between animals
D. congolensis (horses) lesions
- Crusting lesions seen with dermatophilosis
- Rain scald: back
- Dew poisoning: lower extremities when horses kept on wet pastures
D. congolenesis (sheep) lesions
- Crusting lesions seen with dermatophilosis
- Lumpy wool or ‘mycotic dermatitis’: skin
- ‘strawberry footrot’: distal extremities
D. congolenesis treatment (sheep)
- topical disinfectants
- antimicrobials (depending on animal species)
- *wear gloves
D. congolenesis management
- remove from wet environment
- discard crusts=source of infection for other animals
D. congolensis associated lesions (various species)
- suppurative and hyperkeratotic epidermiditis
- hyperplastic skin with crusting lesions and coagulation necrosis
D. congolensis (dogs and cats)
- exudative skin disease
- dogs: superficial on haired skin
- cats: often abscessation
D. congolensis (dogs and cats) treatment
- keep skin dry and clean
- bathing and crust removal
- antibitoics (penicillins)
Trueperella pyogenes clinical significance
- wide variety of suppurative infections
- opportunistic=no ‘classical presentation’
- often component of polymicrobial infections
o Fusobacterium necrophorum - spreading via septic emboli=common theme
Trueperlla pyogenes ‘no classical presentation’
- laryngeal abscesses in claves
- liver abscesses in cattle
- component of BRD (shipping fever)
- arthritis, osteomyelitis, subcutaneous abscesses in pigs
Trueperella pyogenes (cattle): liver abscess exemplifies role of septic emboli in pathogenesis (steps)
- Cattle fed highly fermentable diet
- Rumenitis results in lactic acidosis
- Translocation of rumen microbes into portal venous system
a. Can get abscessation of caudal vena cava - Septic emboli spread through venous system to R side of heart and into lungs
- Bacteria get stuck in capillary beds and set up secondary sites of infection
Actinomycetales are fascinating group of bugs
- Seen Arthrobacter sp grown from air in Mir space station
- Brevibacterium: ‘cheese’ odour
Species to collect for culture and microscopy
- Exudates, aspirates
- Fluid aspirated by thoracocentesis: companion animals (pyothorax)
- Crusts: D. congolensis
- Mastic milk
Histopathology samples
- Granuloma biopsies
Sample handling
- For histology fix in 10% formalin
- Do NOT freeze samples for culture
Lab ID: smears of aspirates
- 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
Lab ID: culture
- 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
Actinomyces spp. zoonotic/interspecies transmission
- Commonly part of oral microbiota
- Disease not classically transmitted from animals
Trueperella pyogenes zoonotic/interspecies transmission
- Human infections rare, not major concern
Dermatophilus congolensis zoonotic/interspecies transmission
- Skin infections possible in people in contact with infected animals and have skin trauma (insect bites)
- *wear gloves
Treatment options: actnomyces spp.
- Penicillins
Treatment options: nocardia spp
- Sulfonamides or sulfa/trimethoprim
Treatment options: trueperalla pyogenes
- Pencillins
- tetracyclines
Drugs to avoid?
- Most actinomyces spp. are METRONIDAZOLE RESISTANT
