Gram Pos: Actinomyces, Dermatophilus, Trueperella, Actinobaculum

Question 1

Describe Actinomyces key bacterial characteristics.

Answer 1

-gram pos
-club shaped robs
-filamentous branching
-facultative or strict anaerobic & capnophilic (require CO2)
-non spore forming & non motile
-micro colonies growing in center of lesion surrounded by macrophages “sulfur granules”
-outer zone of lesion is granulomatous (chronic inf)
-commensal of oral cavity
>nasopharyngeal & oral mucosae

Question 2

Describe virulence factors & pathogenesis.

Answer 2

-pyogranulomatous disease
-poly microbial inf w oropharngeal microbiota
-common in active outdoor animals (hunting dog)

Question 3

Describe the species of vet IMP.

Answer 3

Question 4

Describe actinomyces bovis.

Answer 4

‘Lumpy jaw’
-pyogranulomatous osteomyelitis
>mandible, maxilla, other bony tissues of the head
-intro of bacteria via penetrating wounds of oral mucosa like hay or sticks
-facial distortion, loose teeth, dyspnea from swelling into nasal cavity
-predisposition = trauma in oral cavity

Question 5

Describe actinomyces bovis diagnosis.

Answer 5

-CS: swelling of jaw w fistulous tracts discharging purulent exudate
-microscopy of crushed granules from aspirates in unopened lesions
-radiography for degree of bone destruction
-culture purulent material (capnophilic)

Question 6

Describe actinomyces bovis treatment & control.

Answer 6

Treatment
-sus to pen G & iodine = toxicity
-long term treatment (3-12mo) w high dose pen
-lesion sm & circumscribed = surgery w excision of foreign body & lesions
-chronic lesions are walled off micro colonies -> prolonged antimicrobial therapy may fail *
Control
-min risk of mechanical injury
-remove foreign body

Question 7

Describe Dermatophilus key bacterial characteristics.

Answer 7

-gram pos rod
-filamentous branching hyphae
-aerobic
-motile asexual zoospores *
>coccoid fragments ‘tram track’
>penetrate into epi & spread = inflammation
>normal protective skin barriers are deficient
-obligate pathogenic skin bacteria
-severe inf of traumatized & persistently wet skin w formation of scabs & crust (acute & chronic) *
-tropics more prevalent
-zoonotic via skin contact * or arthropods
-epi abscess & hyperkeratosis

Question 8

Describe the pathogenesis of Dermatophilus congolensis.

Answer 8

1. Hyphae grow from cocci -> spread into epi (Ag release) -> IR -> Ab in exudate prevent establishment of inf or excel lesion resolution (crusts 7d after infection)
2. Non resolution of lesions w repeated cycles of epi prolif -> bacterial invasion -> release exudate -> influx of neutrophils, T cells, plasma cells in dermis

Question 9

Describe species of vet IMP of Dermatophilus congolensis.

Answer 9

Question 10

Describe Dermatophilus congolensis.

Answer 10

exudative epi w scab
1. Filament colonize hair follicles & penetrate skin
2. Inflam cell layer formed under inf epi & keratinizes -> scab & crust
3. Accumulate cutaneous keratinized wart like material + matted hair
*morbidity, mortality, loss of body condition, dec milk prod, inc SCC in milk

Question 11

Describe Dermatophilus congolensis diagnosis & treatment.

Answer 11

Diagnosis
-lesions
-detection in stained smears or histology from scabs
-cytologic exam of fresh crust w giemsa stain
Treatment
-parenteral administration of antibiotics
-topical treatment less effective

Question 12

Describe Dermatophilus congolensis control.

Answer 12

-isolate & treat clinically affected animals
-shelter for rainfall
-clear grazing area of thorny scrub
-reduce tick infestation
-prophylactic use of long acting tetracyclines in endemic regions
-control inter current disease
-resistance thru modification of skin microbiota

Question 13

Describe Trueperella key bacterial characteristics.

Answer 13

-gram pos pleomorphic bacteria
-facultative anaerobic & capnophilic
-non motile, non spore, non capsulated
-MM of GIT, respiratory tract, urogenital tract of cattle & swine
-survive in environment
-opportunistic pathogen of cattle, sheep, swine *
-suppurative inf *
-bacteremia *
-sporadic by stress/trauma
-pyolysin = hemolytic toxin, cytotoxic for neutrophils & macrophages
>dermatonecrotic & lethal for lab animals

Question 14

Describe the species of vet IMP of Trueperella.

Answer 14

Question 15

Describe Trueperella pyogenes.

Answer 15

‘Summer mastitis’
-mastitis in nonlactating cows & heifers during summer *
-synergistic action
-transmission of inf by head of fly (hydrotea irritans) during damp conditions
-affected quarter is swollen, hard, painful, hot & enlarged
>thick, clothed like grains of rice w green/yellow pus

Question 16

Describe Trueperella pyogenes diagnosis, treatment & control.

Answer 16

Diagnosis
-smear & gram stain of purulent material
-necropsy & isolation of bacteria
Treatment
-pen G for chronic inf
-reports of resistance
Prevention
-prevent primary cause
-no vaccine

Question 17

Describe Actinobaculum key bacterial characteristics.

Answer 17

-actinobaculum suis *
-gram pos rods
-anaerobes *
-non motile, non spore forming
-commensal in preputial diverticulum *
-not in urogenital tract of healthy sows *
-transmitted at coitus *
-fatal bc renal failure *
-porcine cystitis & pyelonephritis (3-4wk post coitus)
>anorexia, arching back, dysuria, hematuria