Learning about tubercle bacilli is quick and easy

- neither gram negative nor gram positive
- acid fast. resembles gram negative

• very thick
• has mycolic acid

- membrane is even less fluid than some of the other membranes
- infection by inhalation or ingestion
- invades macrophages
- tubercle (nodule) is primary lesion. Forms at initial site of infection
- eventually, more macrophages attracted by cytokines will be able to fight the pathogen

• will destroy (or at least arrest) the bacilli
• will also destroy tissue and exacerbate disease

- diagnosis: lesions are characteristic. However, must culture M. bovis to confirm
- positive test doesn't necessarily indicate dz; probably indicates persistence of bacilli
- vaccines: killed vaccines not effective. BCG most dominent TB vaccine in the world. Animals not vaccinated b/c then would always test positive.
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Bordetella bronchiseptica

- can affect pigs, rabbits, guinea pigs, other rodents

- many afflictions (see notes) but notably rhinitis atrophicans: acute rhinitis progressing to deformations of the turbinate bones, nasal septum and upper jaw

VIRULENCE FACTORS OTHER THAN LPS (toxin), FIMBRIAE (colonizing factor)

- other colonizing factors: filamentous hemagglutinin, pertactin

- other toxins: adenylate cyclase (hemolysin), type 3 secretion system, dermonecrotic (heat-labile) toxin, tracheal cytotoxin, transferrin/lactoferrin binding proteins, siderophore

therapy: susceptibility testing

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Bordetella

- respiratory tract

- strict aerobes

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Actinobacillus lignieresii

- causes "Wooden tongue"

VIRULENCE FACTORS

- proteases

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Actinobacillus (Haemophilus) pleuropneumoniae

- morphology resembles Pasteurella

- hemorrhagic necrotizing pneumonia, fibrinous pleuritis in pigs

- high morbidity; lethality depends on environmental factors

- no healthy carriers

- survivors end up with chronic pneumonia

- transmission: aerosol

VIRULENCE FACTORS OTHER THAN LPS AND CAPSULE

- cytotoxins

- porcine transferin binding protein (lends host specificity)

therapy: penicillin

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Taylorella (Haemophilus) equigenitalis

- stallion = asymptomatic reservoir

- transmission is venereal

- sensitive to desiccation

- therapy: penicillin

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Histophilus somni

- cattle = asymptomatic reservoir

DISEASES

- infections of the respiratory tract (thromboembolic meningoencephalitis)

- endometritis and abortion in cows

VIRULENCE FACTORS IN ADDITION TO LOS

- surface protein that binds bovine transferrin/iron

- Fc receptors have antiphagocytic effect

- resist neutrophils

- can survive w/in macrophages

REQUIRES

- thiamin (vitamin D1) pyrophosphate

- also likes CO2 (capnophilic)

therapy: penicillin

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Haemophilus parasuis

- causes Glasser's dz in 2w.-3mo. old stressed pigs

- therapy: penicillin

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