bacteria pyogranulomatous infections Flashcards
pyogranulomatous infections
chronic and acute inflammation
macrophages, monocytes, neutrophils, lymphocytes
generally act as intracellular and extracellular
gram positive rods rules of thumb
Less frequently isolated than other groups of bacteria
* but some important diseases!
They “tend” to cause syndromes
* therefore – History, Signalment and Clinical Signs often give a good Presumptive Diagnosis
If more definitive diagnosis is required
* morphology is VERY helpful
Actinomyces
facultative aerobe
gr + filamentous branching rods
Most species are normal flora of the oral cavity and GIT of many species
Disease is OPPORTUNISTIC
Requires “something” to allow access of organism into diseased site
AND disease is usually NEAR where they are normal flora!!!
nocardia
Gram +, filamentous, branching rods
strict aerobe
Saprophytes – found in soil and decaying vegetation
Disease is still OPPORTUNISTIC; but they are very poor pathogens
Usually requires significant compromise (e.g., tissue damage or immunocompromise) or many organisms!
Facultative Intracellular Parasite
dermatophilus
Gram +, filamentous, branching rods
strict aerobe
Obligate parasite of the skin
but can survive in the environment for a long time
Reservoir are carrier animals (mainly ruminants and horses) and fomites (e.g., horse brushes)
Requires an alteration in the skin for invasion – usually wetting
Directly transferred from infected/carrier animal to susceptible animal when they:
* rub against each other (contagious)
* transferred by insects (flies, ticks),
* by contaminated fomites (scabs, sheep dips, brushes, etc.)
Motile zoospores aid invasion
Rhodococcus equi
strict aerobe
Gram +, short club-shaped rods
looks like pink spit on blood agar
**Saprophytes **
* found in soil
* secondary in GIT of horses
* animal manure
Infections through inhalation (most common) or ingestion of the bacteria
Facultative Intracellular Parasite
Actinomyces bovis
“Lumpy Jaw” dz
mostly in cattle - other species (e.g., humans, marsupials)
requires some alteration to mucosa/skin to allow access of organism into site of disease production
frequently grass awns, sharp feed, or impacted feed
Invasion results in chronic, pyogranulomatous osteomyelitis of the mandible or maxilla
see hard, usually non-painful, “lumps” on the head of cattle
clinical signs are due to** impairment of function rather than toxemia** associated with bacteria
What diseases do actinomyces usually cause?
Lump jaw in cows
Abscesses
* Pyogranulomatous lesions
* Many species of animals
* Commonly secondary to bite or traumatic injury (e.g., migrating grass awns – A. hordeovulneris)
* Usually mixed flora involved
* May extend into vertebrae etc
Serositis- inflammation of serous surfaces
* Mostly in dogs and cats
* Usually involves thorax, but may extend to abdomen etc
* Direct instillation (e.g., trauma, fighting) or migrating grass awns
Abscesses
- Pyogranulomatous lesions
- Many species of animals
- Commonly secondary to bite or traumatic injury (e.g., migrating grass awns – A. hordeovulneris)
- Usually mixed flora involved
- May extend into vertebrae etc
serositis
inflammation of serous surfaces
* Mostly in dogs and cats
* Usually involves thorax, but may extend to abdomen etc
* Direct instillation (e.g., trauma, fighting) or migrating grass awns
What diseases does Nocardia cause?
Pyothorax/Peritonitis
* Mostly in dogs and cats
* Mostly in immunocompromised individuals
* Usually involves thorax, but may extend to abdomen & other sites
* Poor prognosis in some cases
* “tomato soup” exudate
Abscesses
* In dogs and cats
* Mostly in immunocompromised individuals
* Pyogranulomotous lesions
Bovine Mastitis
* Economical important form of mastitis in cattle
* Associated with intramammary infusions
* Poor prognosis and can’t cure (cull)
remember Nocardia is a weak pathogen
Dermatophilis congolensis diseases
Dermatophilosis
* Also called “Rain Scald”, “Greasy Heel”, “Lumpy Wool”, “Strawberry Footrot”
* Affects many species but most commonly ruminants and horses
* Usually occurs in prolonged wet conditions: causes skin maceration
* allows organisms to invade epidermis
* Basic lesion is an exudative dermatitis
* Get thick scab formation in these areas
* See characteristic bacteria in these lesions
Rhodococcus equi diseases
“Rattles”
* Pyogranulomatous bronchopneumonia of foals
* Significant cause of morbidity and mortality in foals world wide
* May disseminate to other sites including joints
* May also be associated with type III hypersensitivity reactions
Cellulitis/Lymphadentis
Pyogranulomatous lesions particularly in cats
Spread to local lymph nodes
How to treat Actinomyces and Dermatophilus
Penicillin +/- Streptomycin or Tetratcylines
how to treat Nocardia
intracellular
Unpredictable, therefore recommend susceptibility testing
