Line 1: |
Line 1: |
− | ===Overview=== | + | {{frontpage |
| + | |pagetitle =Actinomycetes |
| + | |pagebody = Actinomycetes organisms are gram positive bacteria that grow slowly on media and produce branching filaments. They are associated with opportunistic infections causing inflammatory responses and granulomatous reactions; animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''. |
| | | |
− | *Gram positive bacteria
| + | Actinomycetes organisms are non-motile, non-spore-forming bacteria which are anaerobic or facultative anaerobes that typically colonise mucous membranes. They will grow on enriched media and are non-acid fast, Modified Ziehl-Neelson negative when stained. |
− | *Grow slowly on media and produce branching filaments
| + | Clinically, this class of organisms includes ''Micropolyspora faeni and Thermactinomyces vulgaris'' - these are implicated in [[Extrinsic Allergic Bronchio-Alveolitis|Bovine Farmers Lung]] and ''Thermactinomyces vulgaris'' is associated with the pathology of [[Recurrent Airway Obstruction|RAO]] in horses. |
− | *Opportunistic infections causing inflammatory responses and granulomatous reactions
| |
− | *Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
| |
| | | |
− | ===''Arcanobacterium, Actinomyces'' and ''Actinobaculum'' species=== | + | |contenttitle =Content |
| + | |contentbody =<big><b> |
| + | <categorytree mode=pages>Actinomycetes</categorytree> |
| + | </b></big> |
| + | |logo =bugs-logo copy.png |
| + | }} |
| | | |
− | *Non-motile, non-spore-forming bacteria
| + | [[Category:Bacterial Organisms]] |
− | *Anaerobic or facultative anaerobes
| + | [[Category:Gram_positive_bacteria]] |
− | *Grow on enriched media; non-acid fast
| |
− | *Colonise mucous membranes
| |
− | *Modified Ziehl-Neelson negative
| |
− | | |
− | | |
− | <big>'''''<ncl style=compact maxdepth=2 headings=bullet headstart=2 showcats=1 showarts=1>Category:{{PAGENAME}}</ncl></big>
| |
− | ''[[Arcanobacterium pyogenes]]''
| |
− | | |
− | ''[[:Category:Actinomyces|Actinomyces]]''
| |
− | | |
− | | |
− | ===''[[Actinobaculum suis]]''===
| |
− | | |
− | ===''[[:Category:Nocardia|Nocardia]]''===
| |
− | | |
− | | |
− | | |
− | | |
− | ===''Dermatophilus congolensis''===
| |
− | | |
− | *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 are 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 - WikiBlood|neutrophils]]
| |
− | **Microabscesses are formed in the skin
| |
− | **Raised crusts develop in the affected regions
| |
− | *[[Bacterial skin infections - Pathology#Dermatophilosis|'''Pathology''']]
| |
− | *'''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
| |
− | | |
− | | |
− | *''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and Bronchioles Inflammatory - Pathology#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
| |
− | *''Thermactinomyces vulgaris'' may cause [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]
| |
− | [[Category:Bacteria]] | |