Lecture 18. Liver Infections 1

What is the primary etiological agent of liver abscess and necrobacillosis?

Fusobacterium necrophorum

etiology of Fusobacterium necrophorum

Gram-negative anaerobic rod.

Fusobacterium necrophorum

what causative agent of liver abscesses is indicated in this image

What are the two biotypes of Fusobacterium necrophorum?

1. Biotype A (subsp. necrophorum, most prevalent)

2. Biotype B (subsp. funduliforme, less prevalent and typically a coinfection)

Where is Fusobacterium necrophorum normally found in the body?

It is part of the normal flora of the oral cavity, upper gastrointestinal tract, and respiratory tract.

What is the second most common pathogen associated with liver abscess?

Trueperella pyogens.

What type of bacteria is Trueperella pyogens?

A Gram-positive facultative anaerobe.

Trueperella pyogens

what causative agent of liver abscesses is indicated in this image

What are some virulence factors of Fusobacterium necrophorum?

1. Lactate utilization

2. LPS

3. leukotoxin

4. hemagglutinin

5. hemolysin

How does leukotoxin contribute to the virulence of Trueperella pyogens?

It protects T. pyogens and itself from phagocytosis.

What role does hemolysin play in the pathogenesis of liver abscess?

It damages erythrocytes, creating an anaerobic environment.

What synergistic interaction occurs between Trueperella pyogens and Fusobacterium necrophorum?

T. pyogens creates an anaerobic environment and provides iron for F. necrophorum's growth.

What disease conditions are associated with Fusobacterium necrophorum?

1. Hepatic necrobacillosis

2. digital necrobacillosis

3. oral/laryngeal necrobacillosis in calves

what predisposes cattle to liver abscess

In grain-fed cattle, secondary to rumenitis.

how does the liver abscess actually form

drainage from liver lesions leads to embolic translocation and entrapment of bacteria in the liver

What is the primary clinical sign of liver abscess?

Typically subclinical, but can lead to abdominal pain and slaughter condemnation.

what sound do cattle suffering from liver abscess often make

grunting

What diagnostic methods are used for liver abscess?

1. Morphological diagnosis for liver abscess

2. etiologic diagnosis for liver necrobacillosis

3. ultrasound

4. anaerobic culture of deep edge liver lesion

liver abscesses

the pathology of this liver indicates...

What is a significant laboratory finding in liver abscess cases?

Leukocytosis with marked neutrophilia.

What is the common treatment for liver abscess ? (keep in mind it isnt treated often)

High doses of antibiotics such as procaine penicillin G, oxytetracycline, and ampicillin.

What is the primary control method for preventing liver abscess?

Feed management to avoid ruminal acidosis.

What prophylactic measure can be taken to control liver abscess?

Antibiotic prophylaxis with tylosin phosphate.

What type of vaccine is available to reduce the severity of liver abscess?

Leukotoxin vaccine.