- Cause peritonitis in dogs and peritonitis in cattle and peritonitis in pigs
- Micropolyspora faeni and Thermactinomyces vulgaris in Bovine Farmers Lung
- Thermactinomyces vulgaris may cause COPD
Overview
- Gram positive bacteria
- Grow slowly on media and produce branching filaments
- Opportunistic infections causing inflammatory responses and granulomatous reactions
- Animal pathogens include Actinomyces, Arcanobacterium, Actinobaculum, Nocardia and Dermatophilus
Arcanobacterium, Actinomyces and Actinobaculum species
- Non-motile, non-spore-forming bacteria
- Anaerobic or facultative anaerobes
- Grow on enriched media; non-acid fast
- Colonise mucous membranes
- Modified Ziehl-Neelson negative
Arcanobacterium pyogenes
- Characteristics:
- Formerly known as Actinomyces pyogenes and Corynebacterium pyogenes
- Small facultatively anaerobic rod
- Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
- Produces hazy haemolysis after 24 hours; pin-point colonies after 48 hours
- Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
- Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs
- Pathogenicity
- Opportunistic infections following injury or viral/mycoplasma infection in ruminants and pigs
- Extracellular toxins including haemolysin, proteases, DNase and neurominidase
- Haemolytic toxin, pyolysin, member of the thiol-activated cytolysins (pore-forming toxins); possibly cytotoxic to phagocytic cells; dermonecrotising activity
- Clinical infections:
- Suppurative infections
- Abscesses especially in liver
- Lymphadenitis, osteomyelitis, peritonitis and neural abscessation
- Pyometra
- Endometritis
- Summer mastitis
- Ovine foot disease
- Arthritis
- Umbilical infections
- Suppurative pneumonia
- Treatment:
- Penicillin or broad spectrum antibiotics
- Unclassified Actinomyces species isolated from closed cases of Poll Evil and Fistulous Withers
Actinomyces
- Usually long filamentous branching Gram positive rods
- Anaerobic or facultativlyy anaerobic and capnophilic
- Live in nasopharyngeal and oral mucosa
- Cause pyogranulomatous lesions
- Actinomyces bovis
- Found naturally in oral cavity of cattle
- Prefers anaerobic conditions but not strict anaerobe
- Entry of organism into tissues following trauma to the mucosa from rough feed or tooth eruption
- Causes granulomatous inflammation of soft tissues and bone, causing lumpy jaw
- Usually invades mandible to cause osteomyelitis and may extend to surrounding muscles
- The lesions begins as a painless swelling of the affected bone
- Swelling becomes more painful and enlarges over a number of weeks, gaining fistulous tracts which discharge pus
- Organisms found in yellow sulphur granules
- Club colony formation
- Colonies adhere to agar media and are non-haemoltic
- Surgical treatment possible when lesions are small
- Prolonged parenteral penicillin treatment may be beneficial early in the disease
- Actinomyces viscosus
- Commensal of oral cavity of dogs and humans
- Canine actinomycosis
- Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal and pleural surfaces in dogs
- Leads to pyothorax
- Respiratory distress
- Cutaneous pustules in horses
- Abortion in cattle
- Rods contained in soft grey granules which release the organism when squashed
- Two types of colonies: large and smooth colonies with V, Y and T configurations or small and rough colonies with short branching filaments
- Grow in 10% carbon dioxide
- Usually responds to penicillin
- Actinomyces hordeovulneris
- Organism found in seed heads of certain grasses
- Colonies adhere to agar and are non-haemolytic
- Filamentous, branching organisms
- Cause cutaneous and visceral abscessation, pleuritis, peritonitis and arthritis in dogs
- Actinomyces bovis
Actinobaculum suis
- Found in preputial mucosa of healthy boars
- Anaerobic
- Coryneform morphology
- Produces urease
- 3mm diameter colonies with shiny raised centre and dull edge
- Disease transmitted at coitus
- Sows develop disease within 3-4 weeks of mating
- Produces lesions in urinary tract of sows
- Cystitis and pyelonephritis in sows
- Anoreixa, arching of back, dysuria and haematuria
- May be fatal
Nocardia
- Facultative intracellular bacterium
- Aerobic short branching rods
- Non-motile
- Spores from aerial filaments when cultured
- Grow on Sabouraud dextrose agar
- Cell wall contains mycolic acids (hence slightly acid fast)
- Nocardia asteroides
- Found in soil and decaying vegetation - saprophytic
- Opportunistic infection of immunocompromised animals
- Infection via inhalation, wounds or teat canal; also ingestion
- Causes granulomatous lesions in animals
- Canine nocardiosis:
- Thoracic, cutaneous and disseminated forms
- Cutaneous pyogranulomas: ulcers or granulomatous swellings with discharging fistulae
- peritonitis
- pleuritis and pyothorax with fever, anorexia and respiratory distress
- Disseminated lesions
- Treat with appropriate systemic antibiotics for 6 weeks
- Cattle: chronic mastitis; abortion
- Pigs: abortion
- Sheep, goats, horses: wound infections; mastitis; pneumonia
- Survives and multiplies in macrophages
- Superoxide dismutase and catalase as well as a thick peptidoglycan wall prevent activity of phagocytes
- Chronic, progressive disease
- Positive modified Ziehl-Neelson
- Culture on blood agar and incubate under aerobic conditions at 37 degrees centigrade for 10 days
- White, powdery colonies, adherent to the agar appear after 5 days
- Subculture onto Sabouraud dextrose agar yields wrinkled, orange colonies
- Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
- Cell-mediated immunity required
- Nocardia farcinica causes bovine farcy, a chronic infection of superficial lymphatic vessels and lymph nodes
Dermatophilus congolensis
- Aerobic
- Motile zoospores
- No growth on Sabouraud dextrose agar
- Found in scabs and in foci on skin of carrier animals