nocardia, actinomyces, dermatophilus pt. 1

Nocardia

• Strict aerobe

• Catalase positive CP

• Partially acid-fast (MZN-positive)

• Non-motile

• Spore forming (conidia)

• Oxidative

Actinomyces

• anaerobic or capnophilic

• Mostly catalase negative CN

  • Few catalase negative

• Non-acid-fast

• Non-motile

• Non-spore forming

• Fermentative

Capnophilic (carboxyphilic)

Means that carbon dioxide is required for maximum growth

Dermatophilus

• Aerobic or capnophilic

• Catalase positive CP

• Non-acid-fast

• Motile (zoospores)

• Spore forming (zoospores)

• Weakly fermentative

Trueperella pyogenes

Previous Name - Aecanobacterium (Actinomyces) pyogenes

Present Name -

Actinobaculum suis

Previous Name - Actinomyces suis

Present Name -

Nocardia otitidiscaviarum

Previous Name - Nocardia caviae

Present Name -

• Nocardia

• Streptomyces

Soil microorganisms

• Actinomyces

• Trueperella

• Actinobaculum (except A. hordevulneris)

present on mucus membranes of the host animal (oral cavity or nasopharynx)

Dermatophilus congolensis

• only species in the genus

• Maintain itself in small foci of infection on a carrier animal or within scab particles of dust

• Can survice in scab material for up to 3 years

Actinomyces species

• Infection tend to be endogenous

• Cause pyogranulomatous reactions in animal tissues

• Specific virulence factors of species of vet importance have not been identified

Actinomyces bovis

• Gains access to alveolar region of the jaw in cattle from the oral cavity

• Through trauma from mucosa

• Initiates a rarefying osteomyelitis and soft tissue reaction “lumpy jaw”

• periosteal new bone formation in response to infection

• Fibrosis

• Har, immovable, painless mass

• May develop draining tracts

Actinomyces bovis

• mandibular lesions most common in

Granulomatous lesions in the mammary glands

A. bovis have been isolated from sows with ____

Teeth

A. bovis becomes painful if it involves ____

• causes reluctance to eat

Debridement and antimicrobials (penicillin)

A. bovis is treated with ____ & precent the disease by ensuring access to high quality feed

A. bovis

A. bovis

A. hyovoginalis

associated with

• Abortions in sows

• Purulent discharge in sows

• Infections in various sites in pigs and sheep

Actinomyces viscosus

• Causes clinical syndrome in dogs

  • Indistinguishable from that initiated by Nocardia species

• Localized granulomatous lesion in skin & subcutis (antinomycotic mycetoma

• Pyothorac with granulomas in thoracic tissue

Actinomyces viscosus

• Two syndromes can occur (either separate or together):

• results from a cutaneous wound

• Responds well to treatment

Localized granulomatous lesion in skin and subcutis (actinomycotic mycetoma)

Pyothorax with granulomas in thoracic tissue

• May or may not extend to abdominal cavity

• Often a large accumulation of sanguinopurulent pleural fluid containing soft white granules about 1mm in diamete

A. viscosus

Actinobaculum suis

• commensals of the urogenital tract

• Cause of UTI

• typically afebrile

• Hematuria and pyuria

• May be found dead - acute rnal failure

Actinobaculum suis Clinical signs

• ascending infection of the kidney

• An important reason for kidneys to be rejected at slaughter

Actinobaculum suis

• progression to pyelonephritis

Penicillim

Actinobaculum suis - treatment

• antimicrobials - _____

• high hygiene

• Ensuring sufficient access to water

Actinobaculum suis - treatment

• management

Actinobaculum suis

Trueperella pyogenes

• Associated with wide variety of suppurative infections

• Often component of polymicrobial infections

  • Often associated with Fusobacterium necrophorum

• Spreading via septic emboli is a common theme

• Laryngeal abscesses in calves

• Liver abscesses in cattle

• Component of bovine respiratory disease

• Arthritis, osteomyelitis and subcutaneous abscesses in pigs

Trueperella pyogenes

• opportunistic, there is no “classical presentation”

Highly fermentable diet

Truperlla pyogenes

• Liver abscesses in cattle exemplifies role of septic emboli in pathogenesis

  1. Cattle fed _____

lactic acidosis

Truperlla pyogenes

• Liver abscesses in cattle exemplifies role of septic emboli in pathogenesis

  2. rumenitis results from ______

Portal venous system

Truperlla pyogenes

• Liver abscesses in cattle exemplifies role of septic emboli in pathogenesis

  translocation of rumen microbes into _____

  • Can get abscessation of caudal vena cava

• right side of heart and into the lungs

Truperlla pyogenes

• Liver abscesses in cattle exemplifies role of septic emboli in pathogenesis

  • Septic emboli spread through venous system to ____

Capillary beds

Truperlla pyogenes

• Liver abscesses in cattle exemplifies role of septic emboli in pathogenesis

• Bacteria gets stuck in _____ and set up secondary sites of infection

Trueperella pyogenes

Pyolysin

Trueperella pyogenes

• hemolytic exotoxin (most significant)

  • Cytolyctic for neutrophils and macrophages

Neuraminidases and Extracellular matrix-binding proteins

Trueperella pyogenes

• facilitates adhesion to host tissue

• fimbriae

• Proteases

Trueperella pyogenes

• other virulence factors

Biofilms

Trueperella pyogenes

• Exact role of these factors in disease production has not been definitively established

Nocardia species

• Difficult to identify using phenotypic methods

• Many species have been reclassified

• Pathogenic nocardiae can survive within phagocytic vacuoles by preventing phagolysosome formation.

  • Due to surface lipids

Nocardia species

• Cause suppurative and pyogranulomatous reactions in immunocompromised hosts or animals that have been exposed to large doses of the bacterium

Mycobacteria

Nocardia species have a cell wall similar to ____

Superoxide dismutases and catalases

Nocardia species

• Important in resistance to phagocytosis

Cell lipids

Nocardia species

• May provoke the characterisitic granulomatous reaction

Exudates are sanguinopurulent

Nocardia species

• Can sometimes contain soft granules consisting of bacteria, neutrophils and debris

• Lack the microstructure of the sulphur granules produced by some of the Actinomyces specie

Dermatophilus congolensis

• Causes skin infections than can affect many animal species

  • Condition commonly seen in cattle, sheep, goats and horses

  • Characterized by formation of thick crusts which come away easily with a tuft of hair, leaving a moist, depressed area with bleeding points from capillaries.

• alkaline cermadisae

• Protease

Dermatophilus congolensis virulence favors

Lesions occur along the backs of the animal

Dermatophilus congolensis

• Periods of high rainfall

Lesions are present in the predilection sites of the ticks:

• dewlap,

• axillae,

• udder,

• scrotum, and

• escutcheon

Dermatophilus congolensis

• In case of heavy infestations with Amblyomma ticks

Lesions are on the muzzle, head and lower limbs

Dermatophilus congolensis

• In dry season when feed is scarce (in tropical regions)

  • Due to animals foraging in thorn-covered shrub

Dermatophilus congolensis

Dermatophilus congolensis

Dermatophilosis

Crusting lesions seen with

Occurs on the back

Dermatophilus congolensis

• horses

  • Rain scald

Dew poisoning

Dermatophilus congolensis

• Horses

  • occurs on lower extremities when horses are kept on wet pasture

Lumpy wool / Mycotic dermatitis

Dermatophilus congolensis

• Sheep

  • When on skin

Strawberry footrot

Dermatophilus congolensis

• sheep

  • On distal extremities

D. congolensis

Transverse, horizontal, vertical septa

D. congolensis - developmental cycle

• ____ form in the immature filaments dividing them into coccal zoospores

Polar flagella

D. congolensis - developmental cycle

• when mature, zoospores are motile by ____ and are infective

  • They can initiate infection in macerated or traumatized skim of the host animal.

• Topical disinfectants

• Antimicrobials (depending on animal species)

D. congolensis - Treatment

• remove from wet environment

• Discard crusts, source of infection for other animals

D. congolensis - Management

• pus

• Exudates

• Aspirates

• Tissue

• Scrapings

Actinomyces - Specimen Collection

• ______ collected from the walls of abscesses

• A volume of fluid or pus should be collected wnd submitted

• Thin sections of granulomas in 10% formalin are useful for histpathology

• exudates

• Aspirates

• Mastitic milk samples

• Tissues from granulomas

• Thin ssections from granulomas in 10% formalin for histopathology

Nocardia - Specimen Collectiom

For dermatophilus congolensis

Specimen collection

• tuft of hair that is plucked from the lesiom usually detaches with scab material adhering to it.

Sulphur granules

A. bovis and A. viscosus

• best specimens for direct examinatiom

yellowish sulphur granules

Pus or exudate is placed in a Petri dish and washed carefully with a little distilled water to expose the:

• ______ of A. bovis

softer greyish-white

Pus or exudate is placed in a Petri dish and washed carefully with a little distilled water to expose the:

• _____ granules of A. viscosus

10% KOH

A. bovis and A. viscosus granule is placed on a slide in a drop of

Club colonies or rosettes

A. Bovis

Bacterial colonies form in the tissues with “clubs” of mineralized calcium phosphate forming around them to create microscopic _____

Phosphatase activity

Club formwtion is the result pf

Gram-positive, branching filaments

A. bovis and A. viscosus

• If smears are made from granules and stained with Gram stain:

  • _____ can be observed

  • Occasionally, short filaments or pleomorphic diphtheroidal forms may predominate