Actinomyces, Trueperella, Nocardia, and Rhodococcus

Actinobacteria is a extremely diverse group of ____ ____ bacteria with filamentous and branching morphology that resembles what?

gram-positive

fungal hyphae

T/F Actinobacteria is one of the largest bacterial phyla

True

What can Actinobacteria be referred to as?

Higher Bacteria

Infections caused by actinomycetes are characterized by what?

pyogranulomatous suppurative processes with chronic evolution

What is Actinobacteria commonly refractory to what?

conventional antimicrobial therapy

Describe Actinomyces spp by gram stain, and oxygen need status

gram-positive, anaerobic actinomycetes

What does Actinomyces spp cause? What animals does this typically infect?

Cause opportunistic and chronic infections

in cattle and swine

What are the TWO things that the infection are characterized by?

suppurative granulomas and the presence of ‘sulfur granules’

T/F Treatment is rarely successful in chronic disease in which bone is involved, due to the poor penetration of antibacterial drugs into the affected area.

True

Actinomyces bovis Gram-____, anaerobic, ___-shaped filamentous bacteria

positive

rod

What disease does Actinomyces bovis typically cause?

Lumpy jaw in cattle

What are the clinical signs for Lumpy jaw in cattle?

Localized, chronic, progressive, granulomatous abscess

What are the most frequent areas that lumpy jaw infects?

mandible, the maxillae, or other bony tissues in the head

T/F Lumpy jaw has asymmetric swelling

True

What are the TWO route of entry for Actinomyces bovis?

-A. bovis is part of the normal oral flora of ruminants

-A. bovis is introduced to underlying soft tissue via penetrating wounds of the oral mucosa

What are some of the predisposing factors of lumpy jaw?

-Grazing abrasive feeds, coarse hay, sticks, etc.

-Tooth eruption

Involvement of the nearby bone frequently results in ____ ____, loose teeth (making chewing difficult), and ____ ___ due to swelling of the nasal cavity

facial distortion

difficulty breathing

Why is treatment of Actinomyces bovis in chronic cases usually not effective?

-Poor penetration of antibacterials

How do you diagnose Actinomyces bovis?

Presumptive diagnosis is often based on clinical signs

Cytology

The diagnosis can be confirmed by culture of the organism from the lesion. What are the two things to keep in mind?

-Colony has 'molar tooth' morphology on blood agar

-Culture requires anaerobic incubation (generally not practical in clinic setting)

How can you treat lumpy jaw?

sodium iodide IV

What does Intravenous sodium iodide do?

Sodium iodide breaks down fibrous scar tissue that encapsulates the site of infection so antibiotics & immune cells can target bacteria

Is there a vaccine for Actinomyces bovis?

no

What is the goal of treatment for Actinomyces bovis?

the bacteria and stop the spread of the lesion

T. pyogenes are ____ ____, non-endospore forming, nonmotile, Gram-___ and non–acid-fast

facultative anaerobic

positive

What is the shape of Trueperella pyogenes?

Coccoid or pleomorphic rods that tend to form branched filaments in tissues

T/F Trueperella pyogenes in a part of the normal microbiota of healthy animals

True

T. pyogenes is often involved in mixed bacterial infections and is characterized by what?

by a strong proteolytic activity

Trueperella pyogenes opportunistic pathogen and causes suppurative infections – characterized by ____ ____ – such as mastitis, endometritis, and abscesses

pus formation

What does Trueperella pyogenes cause in dry cows?

Summer Mastitis

____ cytotoxin is a major virulence factor of T. pyogenes

Pyolysin

What is the weird animal that you can see Trueperella pyogenes in?

white-tailed deer

pictures on slide 13

okay okay

How do you treat Trueperella pyogenes?

Debridement, drainage, and antimicrobials

Beta-lactams, tetracyclines, and macrolides are the antibiotics most often used

T/F Antibiotic therapy may be ineffective for Trueperella pyogenes

True

____ should be considered as a primary method of T. pyogenes infection prevention

Vaccination

Summer Mastitis" infection in dry cows and heifers primarily during what period?

drying off period and just prior to calving

How is summer mastitis transmitted?

biting flies (horn flies)

What are some of the symptoms of summer mastitis?

Affected quarter is swollen, hot, painful

Thick, clotted, purulent discharge

Lameness and anorexia

How do you treat summer mastitis?

Strip affected teat often to remove toxin-containing exudate

Parenteral and intramammary antibiotics

NSAIDs to reduce inflammation

Teat removal may be necessary

How do you prevent Summer Mastitis?

Fly control!

Dry Cow therapy (+/- antibiotics)

Vaccination

Nocardia are ubiquitous, ___, and saprophytic actinomycetes

aerobic

Where do you normally find Nocardia?

-Soil

-Fresh and salt water

What are some of the things that Nocardia spp causes?

cause of bovine mastitis, cutaneous or subcutaneous abscesses, pneumonia, and disseminated disease

T/F In companion animals, nocardiosis often develops secondary to plant awn migration

True

Nocardia spp is an ____ ____ and has a ___ ___ gram ____ ___

Obligate Aerobe

Beaded filamentous Gram-positive rods (sorry:()

Nocardia spp partially stain how?

acid fast

What helps to differentiate Nocardia from Rhodococcus?

aerial mycelia

What is a A non-contagious granulomatous disease?

Nocardiosis

Nocardiosis is seen in cattle, dogs, cats, horses and humans as a ___ infection

exogenous

What would Nocardiosis Diagnosis look like on blood agar?

Irregularly folded, raised, smooth, or granular white to yellow colonies

In vetmed, Plant Awn Nocardiosis commonly presents as what?

pyothorax in young, active hunting dogs

T/F Migrating plant awns are common initiating factor in no cardiosis infections of the thoracic cavity

true

Pyothorax is usually preceded by what?

rupture of a chronic lung abscess

-Animals inhale plant awns (carrying Nocardia and other bacteria) that migrate into the lung. What does this lead to?

-Leads to the development of multifocal necrotizing pneumonia with abscess formation

How do you treat Nocardiosis?

-Removal of the foreign material

-Surgical debridement and drainage of lesions

-Treatment with sulfa drugs, ampicillin, and tetracyclines

Rhodococcus equi (Prescottella equi) is a facultatively intracellular Gram-____, non-endospore forming ____

positive

coccobacillus

Rhodococcus equi is a what?

Obligate aerobe

T/F Rhodococcus equi is Non-hemolytic but does produce phospholipase (positive CAMP)

True

Important pathogen in foals and occasional pathogen in swine, sheep, goats, cattle, dogs, cats, and humans

-Pneumonia in ___

-Mesenteric ___ and arthritis in foals

-Tubercle lesions in cervical lymph nodes of ___ and ___

-Pneumonia in AIDS patients

foals

lymphadenitis

swine and cattle

R. equi pathogenicity depends on a ___ ____ that promotes intracellular survival by preventing what?

virulence plasmid

phagosome–lysosome fusion

____ are extrachromosomal DNA that often carry non-essential genes that provide a competitive advantage to the host bacterium (ex: antibiotic resistance genes or virulence factors)

Plasmids

Host-specific virulence plasmid encode what?

secreted virulence-associated proteins

What are the proteins that allow R equi to replicate in macrophages?

Horses:

Swine:

Cattle:

Horses: pVAPA

Swine:pVAPB

Cattle: pVAPN

Rhodococcus equi is a ___ ___ infection. Where is it present in?

soil borne

present in the feces of grazing animals, but not in animals housed in pens

What is the mode of infection for Rhodococcus equi?

Inhalation of the dust

Bacteria are inhaled, enter the alveoli, and are phagocytosed by macrophages

Where do they multiply?

Death of the macrophages is followed by what?

-Multiply in the phagocytes and eventually destroy the alveolar macrophages

neutrophilic infiltration and abscess formation

What is the primary disease that Rhodococcus equi causes?

Pneumonia in young foals

What is the most important case of pneumonia in foals less than 5 months old?

Rhodococcus equi

What is the route of entry that causes Pneumonia in young foals?

Inhalation of virulent R. equi is the major route of pulmonary infection

T/F Host-specific virulence plasmid encode secreted virulence-associated proteins

True

T/F Lymph node enlargement is common, but the lymph nodes in the head are where most of the infection is seen

False, the head ln are typically not involved

How do you diagnose Rhodococcus equi?

Based on known history of cases on the farm (indicating presence of the bacteria on the grounds

How do you treat Rhodococcus equi?

-Supportive therapy

Antibiotic therapy

What antibiotics can be used for therapy of R. equi?

erythromycin, clarithromycin, and azithromycin (macrolides - 50s ribosome targeting)

Is there resistance of the bacteria to some antibiotics (macrolides)?

yes some have been reported

What are some of the clinical signs for R equi?

-diarrhea and overheating (hyperthermia)

Are there vaccines for R equi?

No available vaccines for the prevention of R. equi infection

How do you prevent Rhodococcus equi?

Good management!

-Limiting overcrowding of foals

-Housing in well-ventilated areas where dust is minimized

-Avoid dirt paddocks