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29 Cards in this Set
- Front
- Back
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What are four filamentous bacteria
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•! Actinomyces!
•! Nocardia! •! Dermatophilus! •! Streptobacillus! Note: These organisms are linked only by the fact that they form filamentous growths in vivo.! Genetically distinct.! |
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Are Actinomyces gram+/-?
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Gram +
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Are Actinomyces aerobic or anaerobic?
What tissue are they adapted to? |
Anaerobic.
Actinomyces spp. are highly adapted to _mucosal_ surfaces- do not commonly produce disease unless they transgress the mucosal barrier and are deposited under conditions of low oxygen tension! |
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Is Actinomyces endogenous or exogenous? Is it contagious?
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No evidence of protective immunity, animal to animal
transmission does not occur.! This is an endogenous infection. |
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How does Actinomyces establish infections?
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Establish infections by means of traumatic entry to an otherwise _sterile_ site. This site becomes anaerobic and the bacterium can grow.
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What are the channels that Actinomyces create when they get established?
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Once established they can proceed through tissues by means of
histolytic enzymes that allow the organism to extend without regard to anatomical boundaries. Form __sinus tracts_- channels of dead tissues that contain pus and often open to the surface.! |
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How do you diagnose Actinomyces?
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diagnostic trait: _sulfur granules__: hard microcolonies !
(about 0.3 mm) found deep in a purulent sinus tract. ! |
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What bacteria causes bovine lumpy jaw?
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Actinomyces.
Bovine lumpy jaw- chronic infection of jaw resulting from oral A. bovis.! –! Long term, sinus tracts, tooth loss, bone disfigurement. (similar to human cervicofacial actinomyces)! |
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What does Actinomyces cause in horses, dogs, cats, pigs?
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_Abscess__ formation in horses, dogs, cats,
etc.! •! Pigs: mastitis, pneumonia, abortion. |
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Lumpy jaw does what to bone?
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Caused by Actinomyces
Causes suppurative and proliferative _osteomyelitis__! Honeycomb effect of bone damage |
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What does cervicofacial actinomyces result in?
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cervicofacial- common with poor oral hygiene -
periodontal disease- and tooth extraction. Lesions in the jaw give the face a swollen, indurated appearance.! |
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What does thoracic actinomyces result in?
What is it associated with? |
Thoracic- disease in the lungs. abscess formation can
occur. Often associated with _aspiration__ of a lung- oral bacteria establish residence in the normally sterile site. |
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What does abdominal actinomyces result in?
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Abdominal- surgery or trauma in the __bowel__. Also from
diverticulitis. Can eventually involve every organ system.! |
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What does pelvic actinomyces result in?
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Pelvic- 2° manifestation of abdominal actinomycoses, or
primary in the case of an intrauterine device. Can be a simple vaginosis (note: no crossing of mucosal membrane) but also can involve more serious destruction- including tuboovarian abscesses and uretal obstruction. ! |
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What does CNS actinomyces result in?
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Central nervous system- secondary spread from another
infectious site. Commonly a solitary brain abscess.! |
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How can you treat Actinomyces infections?
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Antibiotics: high doses of penicillin may be required for
long periods. ! May also require surgical debridement.! |
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How do foxtail awns relate to actinomyces infections?
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When dog owners talk about "foxtails," they
are actually speaking of the seed portion of the foxtail grass. Once foxtail grasses dry out, the seed detaches easily and sticks readily to clothing and fur. Foxtail seeds can enter a dog's body in a variety of ways and once they enter, they are like a fish hook: The seed only wants to move forward, not backward. It's most common for a foxtail seed to enter a dog's body through the skin, nose, ears, paws, and eyes. Cases have even been reported of foxtails being lodged in male dogs' urethras. One vet mentioned how a foxtail seed found in a dog's lung was believed to have entered initially through the dog's paw! Foxtail seeds are tenacious! Certain species of actinomyces use these plants to traverse within the body- then cause purulent disease.! |
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How is Nocardia different from Actinomyces?
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Nocardia- similar to actinomyces, just _aerobic__ instead of
anaerobic.! Gram stains appear identical. But- no __sulfur granules__.! Is an acid fast organism, actinomyces isn't. |
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What are the characteristics of Nocardia?
What kinds of hosts does it prefer? What are modes of transmission |
Aerobic, saprophytic, gram positive, partially_acid fast__.
Many different mammals, fish, molluscs (?).! Soil organism.! Infection via inhalation,! trauma, ingestion.! |
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What kind of substance is Nocardia's cell envelope made of? What is the signifigance?
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Mycolic acid-based cell envelope"
Corynebacterium, Arcanobacterium (?), Rhodococcus, Mycobacterium! Makes them acid fast. |
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What kind of fatty acids are associated with Nocardia?
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Characteristic long chain fatty acids termed mycolic acids.
For Corynebacteria, chains of _20-40__ carbons For Nocardia, chains of 40-56 carbons For Mycobacteria, chains of ___didn't get it_ carbons These are all acid fast |
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What are key differences between Nocardia and Actinomyces?
(make the two cards like this one) |
Key differences between Nocardia and Actinomyces:!
Acid fastness- Nocardia is, Actinomyces is not.! Nocardia is an aerobe, Actinomyces is anaerobic, capnophilic.! Nocardia grows on Sabaroud dextrose medium, Actinomyces does not.! Actinomyces is sensitive to penicillin, Nocardia is not.! Nocardia is an_environmental_ organism, Actinomyces is a __mucosal_ commensal.! |
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What are the characteristics of bovine nocardial mastitis?
Is it fatal? What kind of exudate does it cause? |
Bovine nocardial mastitis- usually associated
with poor hygiene/milking practices. Pathogen is directly introduced into teat canal with contaminated instruments or fluids. Chronic, ! granulomatous- can lead to sinus tracts. ! Can be fatal via trauma (rupture of udder) or during acute dissemination.! If disseminated: causes suppurative, granulomatous lesions.! Unless caught early, antibiotics may not be successful.! Bovine Farcy- limited to tropics. Systemic suppurative infections that traffic through lymphatics. N. farcinus! |
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What other organism does Actinomyces look like in gram stains?
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Nocardia
Both gram + |
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What is dermatophils congolensis?
What is key to the infection? |
Actinomyces
highly infectious organism- infects many species. Aerobic, causes disease of dermal surfaces. Often insect-borne. Worldwide, but more problematic in tropics. -Attacks areas of damaged skin- _moisture_ is key. -Back and pasterns: most common areas of infection in horses. Lesions are found on head, neck or back. Rain scald or rain rot: (figure 37.4) -Lumpy wool, strawberry footrot: sheep -In general- diseases manifest as a chronic __exudative dermatitis__ with scab formation. -Infection is confined to the dermal layers- in moist environs, and the infection causes exudation that feeds the system. |
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What happens if dermaphilosis is left untreated?
how can you treat this disease? Do insects serve as a resevoir for the pathogen? |
If left untreated, a mud fever infection will spread up the legs.
The legs will swell and be intensely sore. The horse may become lame. Infections in other areas will cause inflammation, soreness and hair loss, severe infections may abcess. Bacteria removed with antiseptics. Beta lactams also can be used. Best way to treat is to keep damaged areas dry- systemic antibiotics can work- but keep animals dry if possible. Address biting insect issues. Do the insects serve as reservoir (as opposed to simply a vector) for pathogen? Not known. Organism likely grows in soil. |
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Does dermatophilosis cause microcolonies?
In what species does in occur? |
Actinomyces
Organisms will form filaments in vivo- individual organisms can break off and start new microcolonies. Dermatophilus is Worldwide, mainly tropics. Many different host species- rarely dogs, cats, pigs. Moisture is key!! |
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What fever is streptobacillus moniliformis?
What kind of infection does it cause in different species? Where is it commensal? Is it zoonotic? |
Streptobacillus moniliformis-!
“_rat bite_ fever”! Febrile joint infections in rodents turkeys, humans…?! Respiratory infections in rodents. ! Commonly acquired from rodent bites. Commensal in rodent _oral/nasal mucosa_.! Septiciemias, arthritic conditions- can be fatal.! In humans- rare- can lead to heart valve problems, death.! 7-10% of diseased humans can die from the infection.! |
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How does streptobacillus moniliformis stain in gram staining?
Is it an aerobe/anaerobe? |
Gram-negative (?) organism!
Grows in chains. Referred to as “Gram-variable”! Facultative anaerobe.! |
