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Redirected page to Category:Actinomycetes
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−<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>+<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
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−*Cause [[Peritoneal cavity - inflammatory#In dogs|peritonitis in dogs]] and [[Peritoneal cavity - inflammatory#In cattle|peritonitis in cattle]] and [[Peritoneal cavity - inflammatory#In pigs|peritonitis in pigs]]
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−===Overview===
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−*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''
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−===''Arcanobacterium, Actinomyces'' and ''Actinobaculum'' species===
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−*Non-motile, non-spore-forming bacteria
−*Anaerobic or facultative anaerobes
−*Grow on enriched media; non-acid fast
−*Colonise mucous membranes
−*Modified Ziehl-Neelson negative
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−===''Arcanobacterium pyogenes''===
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−*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, [[Bones - inflammatory#Osteomyelitis|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 [[Bursae and Tendons - inflammatory#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
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−===''Actinomyces''===
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−*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 [[General Pathology - Chronic Inflammation#Granulomatous Inflammation|granulomatous inflammation]] of soft tissues and bone, causing [[Oral Cavity - Teeth#Mandibular Osteomyelitis|lumpy jaw]]
−***Usually invades mandible to cause [[Bones - inflammatory#Osteomyelitis|osteomyelitis]] and may extend to surrounding [[Muscles - inflammatory#Actinomycosis bovis|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 [[Pleural cavity and membranes - inflammatory#Pyothorax (Thoracic empyema)|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
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−===''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
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−===''Nocardia''===
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−*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
−***[[Peritoneal cavity - inflammatory#In dogs|peritonitis]]
−***[[Bacterial infections#Nocardiosis|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
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−===''Dermatophilus congolensis''===
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−*Filamentous, branching actinomycete
−*Aerobic
−*Produces motile zoospores
−*No growth on Sabouraud dextrose agar
−*Dermatophilosis most prevalent in tropical and subtropical regions
−*Organisms found in scabs and in foci in skin of carrier animals
−*Dormant zoospores become activated when moisture and temperature levels favourable
−*Zoospores may survive 3 years in scabs
−*Pathogenicity:
−**Does not usually invade healthy skin
−**Entrance after trauma or persistent wetting
−**Activated zoospores produce germ tubes which develop into filaments which invade the epidermis
−**Invasion causes an accute inflammatory response with many neutrophils
−**Microabscesses are formed in the skin
−**Raised crusts develop in the affected regions
−*Diagnosis:
−**Giemsa-stained smears from scabs reveal branching filaments containing zoospores
−**Immunofluorescence
−**Scab material can be cultured on blood agar at 37 degrees centigrade, 2.5-10% carbon dioxide for 5 days
−**Zoospores can be cultured
−**After incubation, colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance
−**No growth on Sabouraud dectrose agar
−*Clinical infections:
−**Infection usually confined to epidermis
−**Dermatophilosis
−**Disease most prevalent in young animals
−**Damage to the skin predisposes to infection; blood-sucking insects also thought to be involved in transmission
−**Lesions after heavy rainfall predominantly affect dorsum of farm animals
−**Papules, serous, exudative matting of hair, raised crusty scabs
−**Scab formation more prominent in sheep and cattle than in horses
−**Lesions may resolve within weeks if dry weather, or may progress
−*Treatment:
−**Parenteral antibiotics e.g oxytetracycline, pr penicillin-streptomycin combinations
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−*''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and bronchioles - inflammatory#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
−*''Thermactinomyces vulgaris'' may cause [[Bronchi and bronchioles - inflammatory#Chronic obstructive pulmonary disease (COPD)|COPD]]
#REDIRECT[[:Category:Actinomycetes]]
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